INVESTIGATION O F
MOTORBOAT-INDUCED STREAMBANK EROSIO N
OF THE LOWER DESCHUTES RIVE R
BY
PETER C . KLINGEMA N
HABIBOLLAH MATIN .
CHENG-CHANG HUAN G
FOR TH E
OREGON STATE MARINE BOAR D
WATER RESOURCES RESEARCH INSTITUT E
OREGON STATE UNIVERSIT Y
CORVALLIS, OREGO N
WRRI-104
FEBRUARY 1990
r
INVESTIGATION OF
1
OAT--INDUOM STREAMBAN% EROSION
O N T H E LOVER DESCHUTES RIVER
by
Peter C . Klingeman, PhD
Professor of Civil Engineerin g
Habibollah Mati n
Cheng-Chang Huan g
PhD Students, Civil Engineering Departmen t
through th e
Water Resources Research Institut e
Oregon State Universit y
Corvallis, Oregon 9733 1
fo r
Paul Donheffner, Director
Oregon State Marine Board
Salem, Oregon
David Talbot, Administrato r
Parks and Recreation Divisio n
Oregon Department of Transportatio n
Salem, Oregon
January 31, 1990
ABSTRACT
Streambank erosion conditions were investigated along the Lower Deschute s
River from the Warm Springs Reservation at river mile (RM) 73 .6 to the
Columbia River at RM O . Field work was conducted in August and Septembe r
1989 . Observations were made and special studies were conducted to determin e
the likelihood that bank erosion was due to jetboat waves . Several erosion
zones were identified . The causes and severity of erosion were assessed i n
each case . The role and relative importance of boat-caused bank erosion wa s
identified among other likely causes of bank erosion . The need for bank
erosion control was evaluated and recommendations were developed for contro l
of existing and potential erosion at selected sites .
Streambank erosion along the Lower Deschutes River was found to be only a
minor problem . Combined, less than three miles of streambank experience some
degree of observable erosion along the lower 69 miles of the river . This i s
2 .0 % of the 138 lineal miles of banks in this stretch of river .
The greatest cause of bank erosion is natural erosion by strong currents an d
eddies during floods, at flow constrictions, and where flows are deflecte d
toward the banks . In all, about 1 .7 lineal miles of banks are affected b y
erosion from currents . The second, third, and fourth largest causes of ban k
erosion are humans (camping and foot traffic from hiking and fishing), boat s
(boat waves and direct impacts of boats against banks), and animals (foo t
traffic, grazing and water access) . These affect 0 .7, 0 .3 and 0 .2 linea l
miles of banks, respectively . Thus, natural causes are responsible for abou t
61 % of the observed erosion . Human non-boating activities cause about 24 % ,
motorboats cause about 9 %, and grazing animals account for 6 % of th e
remaining erosion .
Most streambank erosion is due to more than one cause . Secondary causes hav e
increased the amount of bank erosion at some sites over that which would hav e
resulted from the primary cause acting alone .
Streambank erosion is most common near the river mouth . This zone has th e
most intensive human activities .and local animal grazing . But bank erosion
occurs locally throughout the study area .
Motorboat operation is only a minor and local cause of streambank erosio n
along most of the Lower Deschutes River . However, severe erosion at the Stat e
Recreation Area is largely due to boat mooring and waves .
Bank erosion occurs in river reaches where motorboats are excluded . Hence ,
prohibiting the use of motorboats will not halt bank erosion .
Recommendations for general control of streambank erosion in the Lowe r
Deschutes River include a) monitoring erosion zones, b) developing a
public-education effort to prevent erosion, c) reevaluating the locations o f
toilets, campsites and trails, and d) " hardening" assess points between wate r
and land in erosion-prone areas . Recommendations for boat-wave contro l
include a) self-imposed speed control, b) maintaining boat distance fro m
erosion-prone areas, and c) greater care when beaching or docking agains t
banks . It is also recommended that immediate action by taken to halt erosio n
at the State Recreation Area . Options are presented for doing this .
FOREWORD
The Water Resources Research Institute, located on the Oregon State Universit y
campus, serves the State of Oregon . The Institute fosters, encourages, an d
facilitates water resources research and education involving all aspects o f
the quality and quantity of water available for beneficial use . Th e
Institute administers and coordinates statewide and regional programs o f
multidisciplinary research in water and related land resources . The Institut e
provides a necessary communications and coordination link between the agencie s
of local, state, and federal government, as well as the private sector, an d
the broad research community at universities in the state on matters o f
water-related research . The Institute also coordinates the interdisciplinar y
program of graduate education in water resources at Oregon State University .
It is Institute policy to make available the results of significan t
water-related research conducted in Oregon ' s universities and colleges . Th e
Institute neither endorses nor rejects the findings of the authors of suc h
research . It does recommend careful consideration of the accumulated facts b y
those concerned with the solution of water-related problems .
ACKNOWLEDGEMENTS
Special thanks are given to Paul Donheffner, Director of the Oregon Stat e
Marine Board, for his extensive help and support throughout the study . All o f
the boating arrangements and special-permission arrangements that facilitate d
field work were made through his agency . He also joined us in the field fo r
two days to observe the conduct of field work, raise questions in a timel y
manner, and offer suggestions and help to assure that the work went smoothl y
and on schedule .
The assistance of the Parks and Recreation Division of the Oregon Departmen t
of Transportation is also acknowledged with great appreciation . David Talbot ,
John Lilly, Alan Cook, James Payne and James Bader contributed information ,
maps, aerial mosaics, and suggestions during the study, always respondin g
quickly to our needs .
We thank Tom Owens and Mike McLucas for their expert boating services . They
made it possible for us to inspect in detail all river banks in the study are a
and to conduct simple experiments to study wave effects at various banks .
Through their familiarity with the river and with past shoreline activitie s
they provided information useful in our interpretation of observed conditions .
It is also appropriate here to give thanks to Warren Aney, Al Lichens, and Bo b
Phillips, who in 1966 as members of the Oregon State Game Commission took m e
down this same stretch of the Deschutes River by drift boat . The trip was
made to evaluate the sediment impacts on fish habitat between Pelton Dam t o
the Columbia River due to the December 1964 flood and upstream reservoi r
regulation . That trip gave me an enduring interest in the Deschutes River an d
in fish habitat problems . More important to the present study, it gave a
23-year perspective for comparison of present-day bank and channel condition s
with those that prevailed in 1966 .
ii
TABLE OF CONTENTS
Page
Topic
1
Study Area and Scope of Study Study Objectives
•
.
1
Study Sponsors
•
.
1
Study Methods General
Specific Tasks ▪
•
.
.
3
3
3
Streambank Erosion Problems Along the Lower Deschutes River Characterization of Streambank Conditions
Observed Streambank Conditions Common Streambank Erosion Problems Identified
Rate of Streambank Erosion Locations of Severe Streambank Erosion Illustrations of Streambank Erosion Conditions 5
5
6
9
11
13
14
Streambank Erosion Due to Motorboat Waves Bank Erosion from Waves General Aspects of Boat-Wave Erosion Wave Erosion Problems Within the Study Area 43
43
44
45
Relative Role of Motorboat-Caused Streambank Erosion Ranking of Primary Causes of Bank Erosion
Effect of Motorboat Exclusion on Bank Erosion Severity of Streambank Erosion Compared to Other Rivers 47
47
47
49
Streambank Erosion Control Needs Assessment and Recommendations
Streambank Erosion as a Cause for Concern Assessing Erosion Problems and Erosion Control Needs Comparison of 1971 and 1987 Aerial Mosaics to Identify Changes General Recommendations about Erosion Control Recommendations for Erosion Control at the State Recreation Area Recommendations about Boat-Wave Control
51
51
51
53
60
61
63
Study Conclusions 65
References
67
Appendix A - Streambank Condition Observations, by Reach, for the
Lower Deschutes River
Appendix B - Photograph Record, Lower Deschutes River Stud y
Appendix C - Boat-Wave Erosion ; Brief Literature Revie w
Appendix D - Streambank Data for Erosion Study Site at Deschutes Rive r
State Recreation Area
iii
STUDY AREA AND SCOPE OF STUD Y
Erosion problems along the Lower Deschutes River were investigated . Special
attention was given to the likely contribution of motorboats to streamban k
erosion, particularly jet-powered watercraft . The purpose of this study wa s
to put into context and give perspective to boating-caused erosion among othe r
likely causes of bank erosion .
The main investigation area extended from the north boundary of the War m
Springs Reservation, near river mile (RM) 69, downstream to the mouth of th e
Deschutes River (RM 0) . Powerboat operation is allowed throughout this zone .
Special emphasis was given to the lowest 12 miles of the river, from Harri s
Canyon to the mouth . Data from summer 1989 indicate that this river reach ha s
the greatest amount of jetboat traffic (Mitchell, 1989) .
Comparison was made with bank erosion in a short reach just upstream, from R M
69 to RM 73 .6 within the Warm Springs Reservation . Here, motorboat use i s
prohibited and there are other differences in stream corridor management .
Figure 1 shows the Lower Deschutes River study area .
STUDY OBJECTIVES
The objectives of the investigation were to :
1. Identify and characterize all erosion problems found within th e
investigation area ;
2. Make observations and conduct special experiments to determine th e
potential for boat waves to cause bank erosion at erosion-prone zone s
within the investigation area ;
3. Make an analysis of the role and relative importance o f
boating-caused bank erosion, to give perspective to boating-cause d
erosion among other likely causes of bank erosion ;
4. Develop recommendations for the control of existing streamban k
erosion and avoidance of future erosion .
STUDY SPONSORS
The investigation was conducted for the Oregon State Marine Board (OSMB) an d
the Parks and Recreation Division (PARKS) of the Oregon Department o f
Transportation (ODOT) . These two agencies are the study sponsors.
The study involved lands within the Deschutes River Scenic Waterway that ar e
administered by the Parks and Recreation Division . It also involved land
administered by Oregon Department of Fish and Wildlife (ODFW) and the Unite d
States Bureau of Land Management (USBLM) . Therefore, these two agencies als o
had particular interests in the study findings .
1
FIGURE 1 . LOWER DESCHUTES RIVER STUDY ARE A
(Source : Oregon Water Resources Department Map 5 .6 )
2
STUDY METHODS
General
A three-step approach was used to determine the role of powerboats in ban k
erosion in the Lower Deschutes River . First, an analysis was made o f
streambank erosion itself in the study area, including all likely causes .
This step addressed objective 1 . Second, an analysis was made of the
streambank erosion that can result in the study area from powerboat operation .
Objective 2 was satisfied by this step . Third, the two analyses were combine d
to demonstrate the realistic magnitude and relative role and importance o f
powerboat-caused erosion compared to erosion from other causes . This ste p
satisfied objective 3 .
Objective 4 addressed existing erosion problems that threaten the Deschute s
River State Recreation Area but do not affect other shorelines within th e
Deschutes River Scenic Waterway . This objective went beyond the three-ste p
problem analysis to offer some solutions to the problem of bank erosion a t
selected shorelines .
Specific Tasks
Preliminary Site Visit
A preliminary visit to the site was made on August 16, 1989 prior to detaile d
planning of the study . Portions of the upper and lower zones of the study
area (RM 39-52 and RM 0-12) were examined . Other zones were omitted, as the y
were not conveniently accessable . This site visit allowed viewing the genera l
nature and scale of erosion problems in the study area . It was made by car
along access roads, rather than by boat . Observations were supported b y
photographs .
Office Planning of Investigatio n
Office planning of the full investigation was based on the preliminary sit e
visit and study of detailed aerial photograph mosiacs and topographic maps . A
classification scheme was developed to characterize all streambanks as to ban k
materials, vegetative cover, exposure to wave action, existing erosio n
condition, and erosion potential . This scheme helped make efficient use o f
the time during field work .
Field Observation of Bank Erosion and Wave Effect s
A streambank examination was made by boat during September 13-15, 1989 . Thi s
covered the entire 73 .6-mile study area . The general streambank condition an d
any evidence of bank erosion were noted . The classification scheme develope d
in task 2 was used to characterize all streambanks . Information was recorde d
on worksheets, in a photo logbook, and on 1" = 400' composite maps of aeria l
photos prepared by ODOT from a May 1987 flight .
3
Sites were selected and used to study wave-caused erosion . One or more
motorboats were observed passing each site . A limited variety of waves were
observed as the boats passed at moderate and high speeds in upstream an d
downstream directions . Wave effects were observed, photographed and measure d
at sites involving bare banks and banks with riparian vegetation . Erosion
markers were used to estimate the extent of erosion . A distinction was mad e
between new erosion and the disturbance of loose previously-eroded material .
Office Workup of Field Data ; Supplemental Analyse s
All field information was reviewed in the office . Information on streambank
condition and erosion problem zones was transferred to final composite map s
and classification-scheme worksheets .
Interpretations were made of the field data . Text material was prepared t o
accompany the maps and worksheets . It provides an explanation of th e
methodology, map codes, field observations, and significance of results .
Where active erosion was observed, an effort was made to estimate th e
long-term pattern of erosion at the same location . This provided an idea o f
the rates of erosion from various causes in the study area .
Analysis of Erosion Cause s
Interpretative descriptions were prepared to explain the nature ,
characteristics and extent of streambank erosion in the study area . Al l
likely causes for bank erosion in this area were identified and analyzed .
Literature Review of Boat Wave Impact s
A literature search was made on the streambank erosion due to boat waves .
Emphasis was given to cause-effect relations for various vessels and powe r
systems . A summary description of the findings was prepared .
Analysis of Role and Importance of Boat-Caused Erosion ,
All collected information was analyzed to determine the role and relativ e
importance of boating-caused bank erosion compared to other likely causes o f
bank erosion . Text material was prepared to give perspective to boat-cause d
bank erosion .
Recommendations to Control Existing Erosio n
Streambank erosion is occurring at the Deschutes River State Recreation Area .
A problem analysis was completed for this site . Recommendations wer e
developed for the control of existing streambank erosion and avoidance o f
future erosion at this site .
Preparation of Final Repor t
A draft final report was prepared for review with OSMB and PARKS . The fina l
report was then prepared and submitted to OSMB and PARKS .
4
STREAMBANK EROSION PROBLEMS ALONG THE LOWER DESCHUTES RIVE R
Characterization of Streambank Condition s
A classification scheme was developed to describe streambank conditions in th e
study area . A preliminary version of this scheme was tested and revise d
during the first .day of field work in September . The resulting river reac h
characteristics and corresponding descriptive conditions used in th e
classification scheme are shown in Table 1 .
The chosen reach characteristics included types of bank materials, types o f
vegetative cover, degree of exposure to wave action, magnitude of near-ban k
currents, the existing erosion condition, and the erosion potential . An y
unusual conditions observed in the reach were also noted . A few sites wer e
identified for possible use in wave erosion studies .
TABLE 1 . CLASSIFICATION SCHEME USED TO DESCRIB E
STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVER
Characteristic
Choice of Descriptive Conditions
Bank Materials
bedrock (solid outcrop )
dumped rock, ripra p
boulders ;
cobbles ;
grave l
sand
fines (loose )
cohesive (clayey )
- - - - - - - - - - - - - - - - - - - - - - - - - - Vegetative Cover
bare
grass ;
brush ;
trees
abundance
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - Exposure to Wave
none
Action
limited ;
moderate ;
sever e
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Near-Bank Currents
slackwater
sluggish ;
moderate ;
swif t
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Existing Erosion
deposition
Condition
none
limited ;
moderate ;
sever e
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Erosion Potential
non e
limited ;
moderate ;
sever e
- - - - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
5
-
- - - -
- - - -
Observed Streambank Conditions
As the classification scheme was applied, short reaches of the river wer e
identified for which the characteristic conditions remained fairly uniform .
Some such reaches were as short as 0 .7 mile, whereas others were as long a s
10 .7 miles . The entire zone of permitted motorboat use (RM 0 to RM 69) wa s
thus divided into 22 reaches . The zone from RM 69 to RM 73 .6 (the motorboat
exclusion zone in the Warm Springs Reservation) was treated as a single reach .
Appendix A contains the detailed streambank condition sheets for al l
identified reaches . A location map is also shown there for each reach . The
base maps used are US Geological Survey (USGS) 7 .5-minute quadrangle maps .
However, the river mile designations used in the appendix and text fo r
identifying reaches are taken from the ODOT May 1987 aerial photo mosaics ,
because these were used for all field work . The ODOT river mile locations d o
not exactly match the USGS river mile locations in some instances ,
particularly near the river mouth . Where there are discrepancies, the ODO T
river mile location is usually downstream of the USGS river mile location b y
0 .1-to--0 .2 mile .
Table 2 shows the identified reaches having relatively uniform streamban k
conditions . Data include the river-mile locations of the downstream an d
upstream ends of each reach and the corresponding reach length in miles .
Figure 2 shows the locations of these reaches on an enlargement of Figure 1 .
Table 2 also gives a general summary of streambank conditions for each reach ,
based on the classification scheme used and the data given in Appendix A .
Each entry is an "average" for the particular range of observed features . The
broader range of observed features is noted on the worksheets in Appendix A ,
although even these notes represent some visual averaging of the tru e
conditions .
Several pertinent general statements may be made about the Lower Deschute s
River . These help explain the streambank conditions that are encountered an d
the nature of streambank erosion, where it occurs .
Perhaps most significant is the fact that the river flows through a canyo n
over its entire length in the study area . In some places the canyon is quit e
narrow and bedrock is exposed along one or both banks . In other places th e
canyon is wider and provides room for a narrow valley . The river bed has man y
bedrock outcrops . Talus slopes and steep hillsides abound . Because of th e
steep nearby slopes, even the floodplains are quite rocky . They often contai n
boulders that have broken off the canyon walls above and rolled out onto th e
flatter ground . All of these features produce streambeds and streambank s
consisting of coarse alluvial material (gravel, cobbles and boulders) an d
local bedrock outcrops .
The river has a moderate gradient . At RM 73 .6 the bed elevation is nearl y
1100 feet above mean sea level . At RM 0 the level is affected by the surfac e
elevation of the reservoir (Celilo Lake) behind The Dalles Dam and is roughl y
160 feet above mean sea level . Thus, the average river slope is about 13 fee t
per mile . This means that river velocities and shear stresses tend to b e
moderately large . Consequently, small-sized sediment is not likely to stay a t
rest on the bed and banks in areas that are exposed to the main river current .
6
TABLE 2 . GENERALIZED SUMMARY OF STREAMB3ANZ CONDITIONS, LOWER DESCHUTES RIVE R
Reach D/S
RM
U/S
RM
Reac h
Length
miles
Typical
Bank
Materials
Typical
Vegetative
Cover
Typical
Wave
Exposur e
Typical
Near-Bank
Currents
Typical
Erosion
Condition
Typica l
Erosion
Potential
Moderateto-severe
Moderate
Moderateto-severe
Moderateto-sever e
Moderate
Moderate
Limited-to
-moderat e
Limited
Limited trees Severe
Swift
Limited by
bedrock *
Limited b y
bedrock *
Boulders and
sand
Limited trees Moderate
+ gras s
Moderate
Limited-to
-moderat e
Limited
0.9
Bouldery
Limited trees Limited *
+ brush/grass
Moderate
Limited *
Limited *
6 .1
1.0
Bedrock/boulders Limited
gravel/sand
Moderateto-swift
Limited by
bedrock
Limited by
bedrock *
6 .1
7 .6
1. 5
Boulders/sand/
soil
Moderate
Limited *
Limited
8
7 .6
9 .0
1.4
Boulders/gravel/ Sparse grass
soil
LimitedLimited *
to-moderat e
Limited
9
9 .0
11 .3
2.3
Boulders/gravel/ Sparse - some Limite d
sand/soil
trees & gras s
Moderate
Limited
Limited
10
11 .3
12 .0
0.7
Boulders/gravel Trees/brush/
local bedrock
grass
Moderate
Limited-to
-moderate
Limited-t o
-moderat e
11
12 .0
19 .7
7.7
Limited trees ; Limited
Ranges from
boulders to soil brush/gras s
Moderate
Limited *
Limited
12
19 .7
21 .3
1.6
Bedrock/boulders Dense trees ;
gravel/sand
grass
Limited
Moderate
Limited
Limited
13
21 .3
24 .5
3. 2
Boulders/cobbles/ Moderate trees ; Limited
gravel
brush/gras s
Moderate
Limited
Limite d
14
24 .5
30 .0
5. 5
Bouldery
Moderate trees ; Moderat e
extensive grass
Moderateto-swift
Limited ;
deposition
Limite d
15
30 .0
38 .8
8.8
Bedrock/boulders Moderate trees Moderat e
sand/soil
and grass
Moderateto-swif t
Limited
Limited
16
38 .8
43 .5
4. 7
Bedrock and
boulders
Sparce grass ; Moderatetrees
to-severe
Moderateto-swift
Limited by
bedrock
Limited by
bedrock
17
43 .5
45 .1
1.6
Bedrock
Very sparce
(grass )
Swift
Limited by
bedrock
Limited by
bedrock
18
45 .1
48 .3
3.2
Bedrock and
boulders
Moderate trees Moderate
brush/grave
Moderateto-swift
Limited by
bedrock
Limited by
bedrock
19
48 .3
52 .0
3.7
Bedrock/boulders Moderate trees Moderat e
cobbles/sand/soil brush/gras s
Moderateto-swift
Limited-t o
-moderat e
20
52 .0
62 .7
10 . 7
Limited trees/ Moderate
Ranges from
boulders to soil brush/gras s
Moderate
Limited by
bedrock and
ripra p
Limited-to
-moderate
21
62 .7
64 .2
1 .5
Boulders and
cobbles
Swift
Limited-to
-moderate
Limited-to
-moderat e
22
64 .2
69 .0
4 .8
Bedrock/boulders Moderate trees/ Moderat e
gravel/soil
brush ; dense grass
Moderate
Limited-to
-moderate
Limited
23
69 .0
73 .6
4 .6
Bedrock/boulders Moderate trees/ Limite d
gravel/soil
brush ; dense grass
Sluggish-to Limited-to Limited-to
-moderate -moderate * -moderate *
1
0 .0
1 .0
1.0
Ranges from
Mixed trees/
bedrock to soil brush/grass
2
1 .0
2 .0
1.0
Bedrock/
boulders/soil
Mixed trees/
brush/grass
3
2 .0
3 .5
1 .5
Bedrock and
boulder s
4
3 .5
4 .2
0.7
5
4 .2
5 .1
6
5 .1
7
Sever e
Limited trees Limite d
+ grass
Sparce trees
and grass
Limite d
Moderate
Moderate
Moderat e
* Denotes that reach contains locally more severe erosion conditions than "typical " condition
7
Limited-t o
-moderat e
f~~
C
sAr
e.w. . mr. St.~
-~
Sum.
-
N
*rr._ Ir.
So,
s ..
■.w st
A:tl .
orfl~',;g ar ti. l.rl.
[i
gr j Co w
m
:; ''
\
f
y
o
m
FIGURE 2 . DIVISION OF THE LOWER DESCHUTES RIVER INTO REACHE S
HAVING RELATIVELY UNIFORM STREAMBANK CONDITION S
8
1
Instead, sand and silt tend to deposit in overbank areas during periods o f
high water or in wake zones behind protective boulders and bedrock outcrops .
The Deschutes River is regarded as having one of the most stable streamflo w
regimes in the United States . This is largely a result of two natura l
factors . First, the streamflow primarily comes from snowmelt runoff, whic h
usually occurs slowly over several weeks each year . Second, the drainag e
basin is underlain by pervious basalt, into which much of the rain an d
snowmelt seeps and is then released very slowly over the following months .
The flow stability is also an artificial condition that results from upstrea m
reservoirs ; much snowmelt and rainfall runoff is trapped and then diverte d
from the river for irrigation .
Unusual floods can have a severe impact on the Lower Deschutes River . Fo r
example, the December 1964 flood was caused by unusually heavy rain s
accompanied by warm weather that melted much of the accumulated snowpack i n
mountain areas . Many tributaries downstream of Pelton Dam (at RM 103) brough t
excessive loads of sediment to the Deschutes River . But because of uprive r
reservoirs, flow in the main river was not as large as otherwise might hav e
occurred . The actual amount of bank erosion was thus less than the potentia l
erosion from such a major flood . The coarser sediment load (gravel, cobble s
and boulders) from the tributaries tended to deposit near the tributary mouth s
and the finer sediment (sand and silt) tended to deposit on the river bed an d
on low floodplains adjacent to the river . There did not appear to be an y
appreciable vegetation loss in riparian zones due to this flood .
With such tendencies toward a stable riparian environment, one might expec t
denser vegetation along the river banks . Two natural factors may limit th e
abundance of riparian vegetation - the hot dry climate during growing seaso n
and the porous soils that may draw off much of the soil moisture .
A final pertinent factor explaining present-day streambank conditions is th e
impact of past railroad activities . The construction of two competin g
railroad lines, one on each side of the river, caused large amounts of rock t o
be moved . It appears that wherever the railroad lines were placed on fill o r
loose material near the river bank, such that erosion could become a problem ,
rock was dumped to act as riprap protection . Subsequent periodic maintenance
of the right-of-way of the one surviving line has continued to limit ban k
erosion in many places .
Common Streaabank Erosion Problems Identifie d
Field investigation showed that several types of streambank erosion problem s
occurred locally along the lower 73 .6 miles of the Deschutes River . Table 3
lists the common erosion problems identified . Both natural events an d
human-related activities were found to affect streambank erosion along th e
Lower Deschutes River .
Some of ' the identified problems could have been anticipated in advance, base d
on some knowledge of the features and uses of the lower Deschutes River .
However, the location and relative severity of each type of bank erosion coul d
not be anticipated without field inspection .
9
TABLE 3 . COMMON STREAMBANK EROSION PROBLEMS OBSERVE D
ALONG THE LOWER DESCHUTES RIVER
1.
Erosion from natural scouring action of flowing water ,
due to floods, flow constrictions, and flow deflections ;
2.
Erosion due to foot traffic and grazing by animals ;
3.
Erosion due to foot traffic and shoreline activities of humans ;
4.
Erosion due to motorboat operation ;
5.
Erosion due to vegetation failure (root pull-out) ; an d
6.
Erosion due to removal or loss of protective vegetation .
Natural erosion in the study area has occurred in several ways . Flood flows ,
with their higher water levels and greater water velocities, have ofte n
scoured banks that are otherwise safe from erosion . Debris and ice may have
also contributed to bank erosion at such times . At various river discharges ,
local zones occur where the flow is constricted or where the flow is aligne d
toward one of the river banks . These situations subject such banks to higher
velocities than elsewhere and may have caused scour . In some zones, low-flow
riffles occur that are probably "drowned out" by high flows . The resultin g
flow currents have scoured at the base of banks and caused erosion durin g
low-flow periods when erosion might not otherwise be expected .
Activities by humans and animals in the study area have often loosened th e
soil and coarser particles at river banks . These activities have also broke n
down the protective vegetative cover on the banks . Even if erosion does no t
occur immediately, these activities create the opportunity for river current s
to cause erosion, such as when flood flows or boat waves subsequently attac k
the damaged bank .
Motorboat operation has adversely affected river banks in at least three way s
in the study area . One is by the direct impact of boats against the banks .
Another is by the periodic washing of waves against banks that have bee n
damaged by other causes . A third is by the slow, imperceptible loosening an d
washing of soil from the banks in areas that are otherwise undamaged, as wave s
repeatedly strike the bank over time .
Secondary problems occur in the study area that facilitate bank erosion b y
other causes . These include the general loss of riparian vegetation and th e
more-specific vegetation loss due to root failure .
Shelby et al . (1987) comment on erosion problems, as considered a few year s
ago . They note acute public concern over detrimental effects of livestoc k
grazing on riparian vegetation and riverbank stability . This was considered
to be the major ecological impact to the entire Deschutes River Sceni c
Waterway and was most severe between Macks Canyon (RM 24) and the mouth .
10
Table 4 shows the locations and amounts of observed streambank erosion in th e
study area . In some reaches there is more than one location experiencin g
erosion . But other reaches are not undergoing observable erosion an d
therefore are not mentioned in Table 4 .
A total of 17,010 feet (3 .2 miles) of noticeable erosion was found along th e
147+ miles of river banks between RM 0 and RM 73 .6 . Thus, about 2 .2 % of th e
banks show evidence of erosion . Slightly over 1/2 mile is subject to sever e
bank erosion - about 0 .4 % of all banks . Reach 23 experiences relativel y
more erosion than the downstream reaches, including relatively more sever e
erosion .
The apparent causes of erosion at each location are also listed . These ar e
discussed in more detail later in this report .
In most instances, there was little doubt about the causes of erosion . Eve n
if several causes were involved, the primary and secondary causes of curren t
erosion conditions could usually be identified . Except for flood effects ,
most of the causative agents were present during field work - cattle, hikers ,
fishermen, campers, rafts, driftboats, jetboats, paths and trails, trample d
vegetation, exposed tree roots, moored boats, indented banks, waves ,
constricted flows, flows impinging against the banks, debris, growing bars ,
riffles and swift currents near the base of slopes, undercut slopes, etc . In
some places the erosion was even occurring during the field investigation .
Additional information was provided by the boat operators who assisted in th e
field work . They were able to recall river and human activities that they ha d
seen earlier in the year or in past years that helped explain the evidence o f
erosion observed during the field work .
In some instances, the primary cause of erosion could not be confirmed . Thi s
difficulty arose with respect to erosion that probably resulted from floo d
flows -- since the investigation was made during the low-flow season . Durin g
floods, the currents are swifter and the alignment of the flow in the channe l
may be different . To cope with this difficulty, the shape of the eroded bank ,
the location of erosion on the bank, the alignment of the channel, and th e
likely alignment of high-water flows were all considered . These permitted a
qualitative assessment of flood-caused erosion vis-a-vis other possible cause s
of erosion at a site .
Rate of Streasbank Erosio n
The rate of streambank erosion can only be approximately estimated from a
brief investigation such as the present study . In general, bank erosion ca n
be considered to be progressing very slowly - up to a few inches per year i n
zones of moderate erosion .
At two or three areas of severe erosion, the rate of erosion may be rapi d
enough so that the bank line may change visibly each year . These areas are in
reach 23 at RM 69 .2 and RM 72 .8 . Erosion at these locations could amount to
one or more feet of land loss in some years, depending on flow conditions . In
each case, natural flow currents in a bend of the river are the apparen t
primary cause of erosion . For contrast, the erosion classified as moderate i n
reach 20 at RM 57 .2 and RM 61 .7 is not now as rapid as it may have been in th e
11
TABLE 4 .
OBSERVED STREAMBANK EROSION, LOWER DESCHUTES RIVE R
Approx . Approx . Length, ft Apparent Cause of Erosio n
Reach Bank Mid-pt .
Primary Secondary Contributin g
RM
Ltd-Mod Severe
1
1
2
2
3
3
4
5
5
6
7
8
8
8
8
8
9
10
11
11
11
11
13
13
14
15
15
15
20
20
20
20
20
21
22
22
22
Right
Left
Left
Right
Right
Right
Left
Right
Left
Left
Left
Right
Left
Right
Right
Left
Right
Right
Right
Right
Left
Right
Left
Right
Left
Left
Left
Right
Left
Right
Right
Left
Right
Right
Left
Left
Right
0 .7
0 .7
1 .6
1 .7
2. 1
2 .5
3 .8
4 .7
4 .9
5 .6
6 .3
8 .0
8 .4
8 .4
8.6
9.0
9 .9
11 .8
12 .5
12 . 6
16 .0
19 .0
22 .3
22 .5
25 .9
30 .0
30 .2
35 .6
56 .7
57 .2
57 .7
58 .6
61 .7
63 .7
65 .0
66 .0
68 .9
Subtotals : . . . .
23
23
23
23
23
23
23
23
Left
Right
Left
Right
Right
Right
Left
Right
69 .2
70 .2
71 .0
71 .5
72 .0
72 .6
72 .8
73 .5
Subtotals : . . . .
Totals :
400
600
1900
1200
400
20
60
500
40
45 0
80
40
20
700
1500
15 0
30 0
50
100
200
200
200
40 0
10 0
10 0
350
350
900
900
300
400
50
450
12990
200
10
300
20
300
200
1030
14020
350
300
500
20
250
boats
humans ,_
flood s
flood s
boats
humans
humans
boats
flood s
humans
boats ; flood s
humans
boat s
humans
boat s
animals
floods
boats ; human s
human s
floods
boats ; humans
animals
current s
humans
humans
humans (trails )
flood s
humans ; boat s
flood s
humans ; boat s
human s
floods/constricted flow s
floods/constricted flows
currents in ben d
currents in ben d
current s
animals (controlled access )
humans
flood s
flood s
current s
humans
boat s
currents
currents
humans
current s
current s
current s
constricted flow
current s
diagonal flow
current s
humans
curved flow
currents @ RR fil l
flow deflected from bar
1840
350 currents in bend
currents in ben d
humans
animal s
past floods/current s
human s
humans
800 currents in ben d
currents leaving tight ben d
1150
2990 = 17,010 feet of observable erosio n
Note : Does not include some locations where there is eddy-zone depositio n
or erosion, depending upon flow conditions (high or low flow) .
12
past (which would have classified it as severe then) . In these latter two
cases, curving natural flow currents are the primary cause of the observe d
erosion .
Locations of Severe Streambank Erosio n
Table 5 summarizes the observed evidence of severe bank erosion in the stud y
area . This is done by reach . If no entry is made for a reach, there is n o
existing erosion or the observed erosion was limited-to-moderate (there ma y
have been raw banks due to past erosion but little current loss of land) .
TABLE 5 . LOWER DESCHUTES RIVER REACHES HAVING SEVERE STREAMBANK EROSIO N
Reach Downstream Upstream
RM
RM
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
0 .0
1 .0
2 .0
3 .5
4.2
5 .1
6 .1
7 .6
9 .0
11 .3
12 .0
19 .7
21 .3
24 .5
30 .0
38 .8
43 .5
45 .1
48 .3
52 .0
62 .7
64 .2
69 .0
1 .0
2 .0
3 .5
4 .2
5 .1
6 .1
7 .6
9 .0
11 .3
12 .0
19 .7
21 .3
24 .5
30 .0
38 .8
43 .5
45 .1
48 .3
52 .0
62 .7
64 .2
69 .0
73 .6
Reach
Length,
miles
1 .0
1 .0
1 .5
0.7
0 .9
1 .0
1 .5
1 .4
2 .3
0 .7
7 .7
1 .6
3 .2
5 .5
8 .8
4 .7
1 .6
3 .2
3 .7
10 .7
1 .5
4 .8
4 .6
Evidence of Severe Erosion
General along much of right bank
- - - Locally on left ban k
- Locally on left and right banks
Locally on right ban k
- Locally on right bank
One local spot on right ban k
- - - - - - - - - - - Locally on left bank
- - denotes no existing erosion or limited-to-moderate erosion
13
Illustrations of Streambank Erosion Condition s
Several photographs were taken during the field work . These provide graphi c
evidence of the streambank conditions encountered . A record of all of th e
photographs taken is given in Appendix B .
Several photographs were selected for presentation here to illustrate a
variety of streambank conditions . These have been arranged on the followin g
pages according to the apparent primary cause of erosion . Other photograph s
are included to show stable conditions . Short explanatory notes are include d
beneath each photograph and in the title of each figure .
Figures 3 through 10 show the influence of human activities on streamban k
conditions . Among these, Figures 3 and 4 show situations primarily involvin g
boat wave effects . Figure 5 shows effects of cattle grazing and cattle acces s
to drinking water . Figure 6 shows bank erosion from multiple causes . Figure s
7, 8 and 9 show bank conditions associated with camping, fishing, rafting an d
driftboating . Figure 10 shows local erosion protection for the railroad lin e
by use of dumped rock .
Figures 11 through 16 show the influence of natural events on streamban k
conditions . Among these, Figure 11 shows several bank erosion conditions tha t
are mainly due to flow currents . Figure 12 shows the effects of bank erosio n
on tree roots . Figures 13 and 14 provide some indications of erosion recover y
and sediment deposition . Figure 15 illustrates local erosion protection
provided by dense vegetation . Figure 16 shows that the growth of mid-channe l
bars is an important natural condition that can cause nearby bank erosion - in this case aggravating erosion problems due to boats at the State Recreatio n
Area .
14
STREAMBANK EROSION DUE TO MOTORBOAT WAVE S
Bank Erosion from Waves
Waves are known to cause streambank erosion under some conditions . Wave s
dissipate energy as they break on a shallow shore or against a bank . Thi s
energy may be sufficient to temporarily resuspend loose particles . There may
be enough shear stress and pressure change exerted by the waves against tigh t
bank particles to gradually loosen them over time under the repeated attack .
This may also occur at exposed roots, as growing vegetation loosens particles .
Waves may occur in a river due to at least three causes . These are the wind ,
locally-swift currents, and boat use . The first two causes are natural . The
third is human-caused .
The most common and widespread cause is the wind . Bank erosion due to the
wind is particularly common in reservoir segments of rivers . The large flat
open surface provides a long "fetch" or straight distance across which th e
wind can blow . The shear stress of the wind drags on the flat water surfac e
and distorts it into waves . These grow progressively larger in the downwin d
direction, until they either reach a stable size commensurate with the win d
velocity or strike some barrier, such as a shoreline . Because reservoirs ar e
usually subject to periodic water level drawdown, extensive unvegetated zone s
can be exposed to the erosive action of wind-waves . Waves also develop
readily in flat-water stretches of river if the wind has a long fetch acros s
which it can blow . A distance of several hundred feet is sufficient to caus e
moderate-sized waves to develop if the wind is aligned with the river .
Depending on the strengths of the wind and river current, winds blowin g
upstream may generate different waves (perhaps choppier) than winds blowin g
downstream . Because river levels fluctuate seasonally, unvegetated zones
below the riparian vegetation can be exposed to wind-wave erosion .
Rapids in a river may cause the water to toss about wildly
generated by the water in such swift-current zones . These
downstream and toward the banks . Unlike wind-waves, these
and dissipate with distance . This is because the "driving
acts on them after they leave the rapids zone, whereas the
maintain the wind-waves as they approach the shore .
. Often waves ar e
waves then move
waves slowly weaken
force " no longer
wind continues t o
Boats cause waves through the interaction of the moving hull and the rive r
water . Waves may also be generated by objects towed by a boat, such as a
waterskier or a raft or barge . The resulting waves move away from the objec t
toward the banks . Like swift-current waves, these waves slowly weaken and
dissipate with distance because the driving force no longer acts on them .
More than one of the causes of waves may act at any given time and place . The
combined effects may be to either reinforce or dissipate the wave strength .
Thus, swift-water waves may become choppier due to a passing boat and wind s
may strengthen or weaken boat waves or swift-current waves . Depending upo n
circumstances of such interactions, more wave energy may be expended away fro m
the banks or against the banks .
Appendix C presents additional information about wave effects on streambanks .
43
General Aspects of Boat-Wave Erosio n
The preceding discussion shows that boats are a potential cause but not th e
only cause of bank erosion due to waves . Many factors must be considered t o
determine if boats are responsible for a significant amount of bank erosion .
Table 6 identifies several factors that influence the amount of streamban k
erosion that boats may cause . Appendix C gives additional information .
TABLE 6 . FACTORS CONSIDERED TO AFFECT MOTORBOAT-INDUCED STREAMBANR EROSIO N
Streambank characteristics (over a river reach and site-specific) :
bedrock exposure ;
composition of alluvial banks, including types and sizes of alluvia l
material and the extent of cohesiveness/tightness/cementation ;
lateral and vertical features and their variability ;
bank slope ;
bank toe material ;
presence or lack of " forebeach" where waves may break ;
vegetative cover, including its shielding of bank from flow and wave s
and its binding of soil to resist erosion ;
root damage of bank due to collapse of trees and other large vegetation .
River hydrologic characteristics :
water surface elevation (stage) and water discharge .
River hydraulic characteristics :
water depth ;
water velocity ;
channel slope in direction of flow ;
shear stress exerted by flow against bank .
River geomorphic characteristics and their effects on local flow patterns :
planform of the channel, particularly the locations of bends ;
bars and islands ;
bank irregularities and hard points ;
large debris .
Boat wave characteristics :
wave height and wave length ;
angle of waves to bank ;
interaction of waves with any forebeach ;
interaction of waves with bank irregularities ;
influence of boat distance from bank ;
influence of amount of boat traffic ;
relation of wave characteristics to specific bank features .
Boat design characteristics :
influence of motor type ;
influence of boat speed ;
influence of boat hull shape .
44
Wave Erosion Problems Within the Study Are a
Table 4 showed that boats are the apparent primary, secondary or contributin g
cause of bank erosion at several locations . These sites are mainly near th e
river mouth . At one site, the State Recreation Area, the boat-caused erosio n
problems were considered to be severe . Elsewhere, they were considered to be
moderate .
Jetboat activity is particularly heavy at the mouth of the Deschutes River .
There, the public boat ramp provides access to both the Deschutes River and
the Columbia River . Those jetboats going upstream appear to use the lower si x
or so miles most intensively, with use dropping off noticeably above RM 9 .
Boat-caused bank erosion is also mainly evident in these lower reaches, wher e
it is moderate and is often jointly caused by other human activities .
Boating use of the Lower Deschutes River was intensively studied by the OSM B
during July-September, 1989 (Mitchell, 1989) . The resulting statistic s
indicate the potential scope and location of boat-wave problems . For example ,
at Heritage Landing (RM 0 .5) there was an average of 35 jetboat trips per day
from or to the mouth -- a trip being considered as one-way travel . The most
observed was 81 trips . Within the lower 12 miles of the river there was a n
average of 19 trips per day and a range of 3 to 42 trips per day . Less than
50 9 of jetboat trips from or to the mouth also went far enough upstream t o
pass RM 8 .5 . Of all jetboaters surveyed at Heritage Landing, less than 5 %
spent time above Macks Canyon (near RM 24) whereas 62 % stayed below Harri s
Canyon (RM 12 .4) and 48 % stayed below Kloan (RM 7 .5) . Thus, within the study
area, jetboat activity was strongly concentrated in the lowest part of th e
river and boat-wave problems could also be expected to be greatest there .
The severe problems observed at the State Recreation Area are not due to boa t
waves alone . Direct impacts of boat bows against the banks are a major caus e
of bank loss . This happens mainly when boats are being docked . The problem
is viewed as one of poor or indifferent boat handling . Scars on the banks are
obvious signs to approaching boats of damage-prone banks . (A good boat
operator should be able to dock without bashing into the bank, because th e
river current is not very strong at the bank during typical river discharge s
and the mid-channel bar and 5 mph boat speed limit protect the docking zon e
from large waves .) Boat waves and wind waves can reach moored boats an d
contribute to bank erosion at the State Recreation Area . The waves batter the
boats against the banks with lateral and vertical forces that wear away ban k
material . Similar problems may occur elsewhere, but to a much lesser exten t
due to far fewer boats being moored against steep banks (most boats pull up o n
flatter shores) .
45
RELATIVE ROLE OF MOTORBOAT-CAUSED STREAMBANY EROSIO N
Ranking of Primary Causes of Bank Erosio n
Table 7 shows the amount of observed bank erosion on the basis of apparen t
primary cause of erosion . The data are grouped by reach, from the mor e
detailed listing of erosion sites in Table 4 . They are also rearranged on th e
basis of the apparent primary cause of bank erosion, from the extended list o f
primary, secondary and contributing causes in Table 4 . All observed erosion
has been attributed to one or more of the four shown categories .
The total length of observed erosion in the study area is 17,010 feet (or 3 . 2
miles or 2 .19 %), with 2,990 feet of this erosion classed as severe . In
contrast, several river reaches showed no signs of important erosion . In
particular, the 13 .2-mile stretch of river from RM 38 .8 to RM 52 .0 did no t
have observable erosion . However, there are extensive bedrock exposures along
the banks in this zone .
Natural erosion due to river currents is the main cause of streambank erosio n
in the study area . As shown in Table 7, natural erosion accounts for abou t
64 % of the total erosion and affects 10,900 feet (1 .40 %) of banks . Such
erosion is partly due to the scouring effects of flood flows (high velocities )
and any associated debris load or ice load . It is also due to scour caused b y
flows aligned toward the banks, swift flows near the bases of the banks ,
high-velocity flows in constricted zones and at the outsides of bends, an d
eddies downstream of many kinds of irregular channel features .
Human activities that involve hiking, fishing, camping, rafting an d
driftboating are the second most important cause of streambank erosion in th e
study area . These account for about 22 % of the total erosion and affec t
3,810 feet (0 .49 %) of banks . This is only about one-third of the amount of
erosion caused by natural flow conditions .
Motorboat use accounts for about 8 % of the total erosion and affects 1,40 0
feet (0 .18 Z) of banks . This is about one-third of the amount caused by othe r
human activities and about one-eighth of the amount caused by natural flo w
conditions . Erosion from motorboats includes the effects of boat waves an d
the direct impacts of boats against banks .
Animals are responsible for about 5 % of the total erosion and affect abou t
900 feet (0 .12 %) of banks . Such erosion is due to foot traffic on the bank s
for grazing and water access and to the loss of vegetative protection . Pas t
animal-caused erosion may have been much worse (see Shelby et al ., 1987) .
Effect of Motorboat Exclusion on Bank Erosio n
The observed erosion in the lower 69 miles of the teschutes River amounts t o
2 .04 % of the total streambank length . Motorboat use is allowed throughou t
this stretch of river . In contrast, there is twice as much observed erosio n
in reach 23 -- 4 .49 % of the streambank length (2,180 feet out of 48,576 feet )
- even though motorboat use is prohibited in this reach .
47
2:?
TABLE 7 .
SUMMARY OF STREAMBANK EROSION, LOWER DESCHUTES RIVER
Length of Erosion Length by Apparent Primary Caus e
Total
Lower Upper Bank
Reach End End Length, Ltd-Mod, Sev ., Total, Currents, Humans, Animals, Boats ,
feet fee t
RM
RM
feet
feet feet feet
feet
feet
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
0 .0
1 .0
2 .0
3 .5
4 .2
5 .1
6 .1
7 .6
9 .0
11 .3
12 .0
19 .7
21 .3
24 .5
30 .0
38 .8
43 .5
45 .1
48 .3
52 .0
62 .7
64 .2
1 .0
2 .0
3 .5
4 .2
5 .1
6 .1
7 .6
9 .0
11 .3
12 .0
19 .7
21 .3
24 .5
30 .0
38 .8
43 .5
45 .1
48.3
52 .0
62 .7
64 .2
69 .0
Subtotals :
10,560
10,560
15,840
7,392
9,504
10,560
15,840
14,784
24,288
7,392
81,312
16,896
33,792
58,080
92,928
49,632
16,896
33,792
39,072
112,992
15,840
50,688
728,640
1000
3100
60
500
40
450
80
60
700
1500
500
400
1400
1,400
3,100
80
500
390
450
80
880
700
1,500
750
0
300
200
700
0
0
0
0
2,600
300
900
2600
300
900
12,990 1,840
14,830
9,050
3,480
900
1,400
0 .12
6 .1
0 .19
9 .4
20
350
820
250
300
200
700
2600
300
900
3100
80
450
800
700
1500
700
200
200
700
40
500
350
80
80
50
100
Percentages :
100 .00
Relative precentages :
1 .78
0 .25
2 .04
100 .0
1 .24
61 .0
0 .48
23 .5
23
1030
1150
2,180
1850
330
14,020 2,990
17,010
10,900
3,810
900
1,400
2 .19
100 .0
1 .40
64 .1
0 .49
22 .4
0 .12
5 .3
0.18
8 .2
69 .0
Totals :
73 .6
48,576
777,216
Percentages :
100 .00
Relative precentages :
1 .80
0 .38
Notes :
Currents includes flood flows, flow constrictions, misc . flow currents, eddies .
Humans includes foot traffic (hiking and fishing) and camping .
Animals includes foot traffic, grazing and water access .
Boats includes boat waves and direct impacts against banks .
48
The relatively greater erosion in reach 23 is primarily due to natural causes .
The river meanders through the reach more freely than in downstream reaches .
This is partly because bedrock outcrops are quite uncommon in reach 23 and
partly because the valley is wider and has wider floodplains . These factor s
are interrelated . The freedom to meander and the alluvial material that make s
up most banks allows the river to erode the outside banks of tight curves an d
curves near bars .
Erosion due to various human non-motorboating activities is relatively less i n
reach 23 than in the downstream 69 miles . In reach 23, these activities ar e
responsible for about 15 Z of the total observed erosion . In the lower 6 9
miles of river, these activities are responsible for about 23 % of the tota l
observed erosion .
The above comparisons between erosion in reach 23 and erosion in downstrea m
reaches do not provide an adequate basis for reaching any conclusions abou t
the impacts of differences in river corridor management on bank erosion . Th e
natural conditions appear to be sufficiently different to cast doubt on an y
such conclusions . However, the comparisons are important in showing that ban k
erosion does occur even when there is no motorboat use . Stated differently ,
the comparisons show that motorboats are not the only cause of bank erosion .
Severity of Streambank Erosion Compared to Other Rivers
Perhaps the most important statement to be made about streambank erosion alon g
the Lower Deschutes River is that streambank erosion was found to be only a
minor problem! The amount of observed bank erosion seems moderate, compare d
to erosion on many other rivers . This is a subjective comparison . It coul d
be documented and quantified by making studies similar to this study for othe r
rivers . For example, bank erosion problems on the Lower Deschutes River
appear to be much less significant than on the Upper Deschutes River betwee n
RM 190 and RM 215, based on a recent streambank erosion study conducted ther e
(Klingeman, 1989) .
Streambank erosion was not found to be widespread . Bank erosion is quite
limited almost everywhere along the 69-mile reach of river where motorboat s
are allowed to operate . Several isolated zones, generally of short length ,
occur were erosion is limited-to-moderate and may be of some concern . There
are also areas where erosion is moderate-to-severe and is causing a noticeabl e
loss of bank material . But no major change of river course is bein g
threatened in the study area, nor are structures being endangered .
Two factors explain why streambank erosion is so limited . First and mos t
basic, the river flows through a narrow canyon with many bedrock outcrop s
along the river bed and banks that limit the possibility for erosion . Secon d
and equally important, past railroad construction work on both sides of th e
river and subsequent right-of-way maintenance on one side of the rive r
resulted long ago in the placement of riprap in most erosion-prone areas tha t
might threaten the railroad tracks .
49
STREAMBANK EROSION CONTROL NODS ASSESSMENT AND RECOI NDATION S
Streambank Erosion as a Cause for Concern
Streambank erosion due to natural causes is a normal event along any river .
Such erosion will occur whether the river is developed or untouched b y
civilization . All forms of erosion represent a net loss of streambank
material and a retreat of the bankline at the erosion site . However, erosion
at one location is accompanied by deposition at another location . This i s
part of the process by which rivers slowly evolve over time . On a larg e
scale, the valleys and floodplains of a river represent deposition zones an d
the headwater areas represent erosion zones . On a smaller scale, the outside s
of bends and the areas of curved flow represent erosion zones and the inside s
of bends and the areas of curved flow represent deposition zones . Similarly ,
high-velocity zones are subject to erosion whereas low-velocity zones ar e
subject to deposition .
Therefore, the existence of streambank erosion is not itself a cause fo r
concern that something is wrong with the river system . The Grand Canyon i s
the classic example that erosion can even have astonishing aesthetic appeal .
Even on a more conventional scale, erosion can have appeal through the variet y
of bank conditions that it provides . However, where human settlement an d
development occurs along the river, bank erosion may become a cause for alar m
that human uses may become affected .
Human activities and the presence of animals also cause streambank erosion .
This is a common condition along developed rivers . Furthermore, erosion fro m
human and animal causes can aggravate any natural erosion at a site .
Conversely, natural erosion can aggravate any human-caused and animal-cause d
erosion at a site . Hence, concerns over the effects of bank erosion become
compounded when natural causes and anthropogenic causes interact .
Assessing Erosion Problems and Erosion Control Need s
Several general aspects of the erosion process must be kept in mind when ban k
erosion concerns are assessed . A few aspects are given here, before specifi c
recommendations are made about assessing erosion along the Lower Deschute s
River .
Bank erosion is not a steadily continuing process . Often the causativ e
conditions change over time . Sometimes new circumstances will accelerat e
erosion ; sometimes they will halt it . Sometimes a former erosion zone wil l
become a deposition zone .
River erosion and/or deposition conditions can change quite abruptly, as whe n
a large flood occurs . Between such events, river erosion and depositio n
conditions tend to change only slowly .
The rate of erosion of very old alluvial banks that have been part of th e
valley for several decades or longer generally differs from the erosion rat e
for banks that may have only been in place for several years (due to channe l
51
changes and flood deposits) . In the latter case, the material is more likel y
to be loose and quickly eroded . In the former case, the material is mos t
likely to be well consolidated, cohesive, and only slowly eroded .
The adverse effects of bank erosion on human activities can vary from limite d
to severe . But these can change over time due to changes in the processes .
Where erosion is only limited, human activities can often be adjusted t o
accomodate it without great difficulty .
The alignment of flowing water - whether parallel or oblique to the banks - is an important factor influencing the likelihood of bank erosion at man y
sites . If swift enough, flows coming directly or diagonally toward a bank ma y
be able to erode all sedimentary material except large riprap and boulders .
Under natural conditions, only changes of river flow alignment can alter a n
erosion zone and perhaps change it into a zone of sediment deposition . Flow
alignments can change abruptly during floods, either increasing or decreasin g
the rate of bank erosion .
Flow constrictions cause the water velocity to increase in the constricte d
zone and to move in eddies towards the banks just downstream of suc h
constrictions . Such high-velocity flows may be able to erode all but the
largest sedimentary material . The eddies will also erode sedimentary materia l
at some discharges, but may also cause deposition at other discharges .
The presence of streambank erosion is not itself a sufficient reason fo r
implementing erosion control measures . An analysis is first needed t o
determine if erosion control measures are required . The availability o f
suitable methods to fit the erosion conditions and the site must also b e
determined . The analysis should also give guidance on the urgency with whic h
a riparian landowner or manager must act if it is decided that an erosio n
problem must be controlled .
A multi-step analysis of the perceived erosion problem should be made . It ca n
be described in many ways . One approach is given by the several key step s
that follow :
First, the nature of the bank erosion must be assessed . Is it natural o r
anthropogenic? What is the specific cause? Is there more than one cause? I s
the erosion controllable ?
Second, the severity of the existing and potential erosion should be assesse d
How bad is the problem? What is the present rate of erosion? What is th e
likelihood of changing conditions? What is the nature of streambank material s
involved? Will the erosion get worse over time if nothing is done now? How
soon will this happen? What might be the future rates of erosion ?
Third, the risks that the erosion poses for loss of land and for limiting lan d
and river uses should be evaluated . Could there be much land loss? What i s
likely to happen to land uses near the site? Will the erosion affect an y
river uses ?
Fourth, the desirability of trying to control erosion must be determined . I s
it a real problem? Can it be accepted and accomodated without trying t o
control it? Are things likely to happen that can make it worse ?
52
Fifth, the options available for control must be identified, includin g
structural and non-structural (managerial and regulatory) options . What can
be done? How effective will it be? Will the control measure itself introduc e
new problems? Can anything be done about the erosion without adverse effects ?
Sixth, the costs and impacts of control measures must be considered . Thes e
include physical, ecological, economic, legal and social costs and impacts .
What are the direct costs and impacts? What are the indirect costs an d
impacts? Are the resources available to implement the measure? Is the public
acceptability there for implementing the measure ?
These six steps of analysis should provide a solid basis for deciding whethe r
or not to try to control erosion . Only after such an analysis should th e
erosion-control decision be made .
Human- and animal-induced erosion can often be controlled at the source . For
example, management decisions may be made that can eliminate the cause o f
erosion . To reach such decisions, the evaluations described above need to b e
made in terms of the river users as well as in terms of the natural system .
Comparison of 1971 and 1987 Aerial Photos to Identify Change s
The ODOT aerial photo mosaics from June 1971 and May 1987 offer a 17-yea r
comparison of channel conditions . Differences in Deschutes River discharge at
the times of the photographs must be considered . Also, the level of Lake
Celilo must be considered for analysis of those banks downstream of Mood y
Rapids . The actual day during the month for each photo series is not given .
In June 1971 the daily flows varied between 7,350 cfs and 5,640 cfs, accordin g
to published USGS Water Resources Data for Oregon . In May 1987 the dail y
flows varied between 5,580 cfs and 4,560 cfs . Therefore, more of the low rive r
margin was covered by water in the 1971 photos, except perhaps below Mood y
Rapids .
Figures 17 and 18, copied from portions of the ODOT photos, show the genera l
features of the mouth of the Deschutes River in 1971 and 1987, respectively .
Figure 19 shows the same general area, as it is presented in the USGS 197 7
Wishram Quadrangle map based on 1973 aerial photos .
Near the State Recreation Area (RM 0 .7), the present mid-channel bar (se e
Figure 18) was not visible in the 1971 photo (Figure 17) . It could have bee n
small and shallow at that time . However, it is shown in the USGS 1977 ma p
based on 1973 aerial photos (Figure 19) . This bar has grown since 1971 and i s
now vegetated, although the periods of rapid growth are not known wit h
certainty from the photos . The bank line at the State Recreation Area appear s
to have retreated during the 17-year period . Total erosion is evidently les s
than 40 feet . But it can not be judged reliably without enlargements of th e
photos and knowledge of the specific river flows and stages .
Between RM 10 and RM 11, there are some changes in the shapes and sizes o f
some bars . Newer erosion of the right bank is evident at RM 10 .7 and a
slender shallow bar that was just downstream at the left bank appears to hav e
been eroded away .
53
FIGURE 17 . MOUTH OF THE DESCHUTES RIVER IN 197 1
(Source : ODOT June 1971 Aerial Photo Mosaic )
54
FIGURE 18 . MOUTH OF THE DESCHUTES RIVER IN 198 7
(Source : ODOT May 1987 Aerial Photo Mosaic )
55
FIGURE 19 . MOUTH OF THE DESCHUTES RIVER IN 197 3
(Source : USGS Wishram Quadrangle Map, 1977 )
56
Second, it is recommended that a limited amount of erosion be tolerate d
without the need for action, particularly if the erosion is due to natura l
causes . Most of the erosion is not causing any problems .
Third, it is recommended that a modest public education effort be undertaken .
This should alert river users to erosion problems that they may cause o r
aggravate and suggest ways to minimize their impacts on erosion . Such an
effort would easily be added to existing efforts to inform users about litter ,
human wastes, fires, campsites, trespassing, and boating safety .
Fourth, it is recommended that the locations of all toilets, campsites an d
trails be reevaluated with respect to streambank erosion potential . Whil e
some are well-situated, others may need relocation (see next recommendation) .
Fifth, it is recommended that consideration be given to the "hardening " o f
access points from the land to the water, and vice versa, in erosion-pron e
areas . Rocky paths or log steps could be used, for example . Hikers an d
campers need ways to get to the water without breaking down the natural ban k
protection . Boaters need ways to get to the toilets and camping sites withou t
damaging the banks .
Recommendations for Erosion Control at the State Recreation Are a
The only streambank having severe erosion that needs immediate attention i s
that along the Deschutes River State Recreation Area . There, erosion i s
causing loss of valuable land . The erosion is occurring precisely where boat
" docking" and mooring occur . Often a dozen or more boats are present at once .
The banks at the State Recreation Area are highly visible . Any visitor to th e
river near its mouth is sure to notice the severe erosion there . This give s
the viewer a perception that severe streambank erosion is a general proble m
along the river .
The anchored boats at the State Recreation Area site are even more visible .
Nearby moving motorboats generate waves in spite of speed restrictions ; th e
resulting waves visibly rock and batter the moored boats against the bank .
This gives the viewer the further perception that motorboats are the cause o f
the severe streambank erosion . In the case of the State Recreation Area site ,
this perception happens to be true . Elsewhere, however, it is not the cause
of severe bank erosion .
It is recommended that a combination of erosion control and boat moorage b e
provided at the State Recreation Area as soon as possible . This is needed t o
halt severe erosion and the loss of heavily-used park land .
The following paragraphs provide a brief problem analysis for erosion at thi s
site . They also offer suggested ways to implement the above recommendation .
Figures 17 and 18, already presented, show the general features of this sit e
in June 1971 and May 1987, based on the ODOT aerial photo mosaics . Wate r
levels are not known for the two photographs (they probably differed), but th e
general positions of the main features in each figure can be used fo r
comparative purposes .
61
From a hydraulic standpoint, two very important features occur near the mout h
that affect bank erosion at the State Recreation Area . First, the rive r
widens out into a floodplain of alluvial deposits after leaving the stretch o f
broken bedrock and boulders at Moody Rapids . Second, sediment transport fro m
upriver has resulted in the formation of a central bar in the river jus t
downstream of Moody Rapids .
In characteristic fashion for such bars, the central bar has divided the rive r
flow and forced it toward both side banks . At times of high water, the bar
probably is inundated . This allows new sediment carried from upriver by th e
high-water flows to deposit on top of and on all sides of the bar . At such
times, the splitting action of the bar may not be very strong . Also, the
low-lying ground near the opposite banke may be covered by the flood waters ,
so that bank stresses there are not too severe . At times of low water, the
flow-splitting action of the bar is much more important . The growing bar
causes the flows to increase their velocity against the opposite banks ,
increasing the erosive stress . The curvature of the flow induces secondary
currents that sweep eroded material away from the base of eroding banks .
It appears that the central bar has been growing over time and changing it s
position, based on comparison of Figures 17 and 18 . Field examination of th e
bar and nearby riverbed shows that this bar growth involves shallow sand an d
gravel deposits around the bar and deeper water in the two mid-channel zones ,
as well as near the two banks opposite the bar . Such conditions are typica l
of those found in bends of rivers, where a shallow point bar occurs an d
deposition takes place at the inside of the bend while erosion occurs at th e
outside of the bend . It is a reasonable conclusion that the central bar i s
significantly contributing to erosion problems at the State Recreation Area .
Even if there were no human activities at the mouth of the river, the centra l
bar would cause nearby bank erosion .
An hydraulic feature shown in Figure 19 is a shallow zone in the Columbi a
River just downstream of the Deschutes River mouth . This is a tributary bar .
It consists mainly of sand and gravel deposits from the Deschutes River . Thi s
bar offers evidence that the Lower Deschutes River does carry a sediment load ,
even though there are upstream reservoirs that regulate the discharges an d
intercept all sediment from upstream of RM 100 . The sediment sources are th e
tributary streams along the lower reaches of the Deschutes River . Since th e
river carries a sediment load, growth of the central bar is possible . If th e
growth is uneven, the bar will shift in position over time .
Several options exist for erosion control at the State Recreation Area . Thes e
include : (1) place boulder riprap along the eroding bank to completely hal t
erosion ; (2) place boulder riprap at some distance out in the water paralle l
to the eroding bank and backfill the gap with rocks, sand, gravel, and a soi l
cover to completely halt erosion and regain some lost ground ; (3) completely
remove the central bar and place the removed material against the eroded ban k
to realign the channel as a long-term but temporary protective measure ; (4 )
remove part of the central bar and place the removed material against th e
eroded bank as a short-term temporary protective measure ; (5) dredge materia l
from the tributary bar in the Columbia River and place it against the erode d
bank as a short-term temporary protective measure ; (6) build a breakwater o f
boulder riprap to protect the bank from currents and waves ; (7) build boulder
spur dikes from the eroded bank to deflect currents ; and (8) construct a
protective concrete, timber or steel sheetpile wall along the erosion zone .
62
Boat moorage facilities could be incorporated into erosion control work in a
variety of ways . Docks, slips or quays could be built or beaching zones coul d
be provided, for example . A variety of materials could be used .
No design details are mentioned here . Any erosion control measure should b e
carefully designed so that all goals can be achieved in a permanent manne r
without adverse effects .
The various options are presented here merely to stimulate some thinking abou t
management choices for addressing problems . No specific recommendation i s
made as to which option might be most suitable . The important consideration s
in selecting an option should include ability to halt low-flow erosion fro m
boats, ability to prevent high-flgw erosion from floods, ability to provid e
docking and mooring of boats, ability to provide water access for people i n
general, aesthetics, cost, safety, and permanence .
Recommendations about Boat-lave Contro l
The river mouth is the point of greatest public access to and from the Lowe r
Deschutes River . The adjacent interstate and state highways provide eas y
access to Heritage Landing State Park and the Deschutes River State Recreatio n
Area . The State Park provides parking space, a boat ramp and toilets . The
State Recreation Area provides parking space, toilets, campgrounds and a
picnic area . Trails lead up the river on both sides .
The most widespread bank erosion in the entire study area is found near th e
river mouth . Local severe bank erosion occurs at the State Recreation Area - along the picnic and camper campground areas . This erosion is caused by heavy
boat traffic and extensive boat mooring . Moderate local erosion occurs acros s
the river at the State Park . From the mouth upstream for several miles th e
river is heavily used for hiking, fishing and camping . Access is relativel y
easy by foot, trail bicycle, and boat . The heavy usage and the associate d
foot and boat traffic cause the banks to suffer noticeable erosion .
Boat waves, with typical heights of less than six inches, frequently was h
against the banks . In doing so, they disturb the loose sediment at the ban k
where trails enter the water . Furthermore, banks between these access path s
look somewhat eroded, although it is not clear whether this is more due t o
boat waves, people moving along the banks as they fish, or high-water scour .
Probably, all of these are factors . The waves also cause inconvenience an d
potential hazard to people fishing in the shallow margins of the river, man y
of whom stand in water nearly reaching the tops of their wading boots .
Boat waves are quite likely to stir up loose sediment . But they are not ver y
likely to erode tight, protected sediment . Therefore, in the many local area s
of loose previously-disturbed sediment, boat waves do cause sediment agitatio n
and an "erosion-like" effect can be seen by the observer .
For all of the reasons mentioned, there is ample reason for people to b e
concerned that motorboats and boat waves are a major problem and cause ban k
erosion . This may reinforce any prejudices held against jetboats by those wh o
prefer rafting, hiking, or quiet enjoyment of the river . However, the zone
where motorboat use causes an erosion problem is quite local . Furthermore ,
63
bank erosion occurs in many places where motorboats are not the cause fo r
erosion . Hence, motorboats should not be generally blamed for erosio n
problems .
With one exception, motorboat operation is only a relatively minor cause o f
streambank erosion along the Lower Deschutes River . The exception is the
State Recreation Area park, even though a boat speed limit now applies .
Therefore, speed control does not appear to be an effective means o f
preventing bank erosion . For example, boat design features appear to caus e
most jetboats to make smaller wages at high speed than at low speed .
Therefore, it is recommended that no actions be taken to control motorboa t
speeds purely for the sake of erosion control . Put in perspective, spee d
control is a major safety consideration but only a minor erosion consideratio n
on the Lower Deschutes River .
Instead, erosion considerations involving boat use and boat-wave contro l
should focus on four actions . First, erosion-free mooring facilities shoul d
be provided at the State Recreation Area . Second, boats should be encourage d
to keep at a good distance from erosion-prone banks (assuming the local rive r
width and depth are adequate) so that they do not aggravate existing erosio n
problems . Third, boaters should be educated to use greater care and skil l
when beaching or mooring against river banks and to select landing sites wher e
their foot traffic will not contribute to bank erosion . Fourth, boater s
should be asked to become better aware of the wave-generation characteristic s
of their individual boats and to use speeds that minimize the wave height s
whenever operating in erosion zones or near people fishing in shallow water .
64
STUDY CONCLUSIONS
Streambank erosion along the Lower Deschutes River is only a minor problem ,
based on field investigation from the mouth to river mile 73 .6 in August and
September 1989 . This report identifies the zones of erosion, describes th e
causes of erosion, and assesses the severity of the erosion . It als o
illustrates the various types of erosion and their causes in the study area .
Less than three miles of streambank experience some degree of observabl e
erosion along the lower 69 miles of the Deschutes River . This is 2 .0 % of th e
138 lineal miles of river banks in this stretch of river .
The greatest cause of bank erosion is natural erosion by currents . Thi s
includes bank scour from flood flows, at flow constrictions, by eddies, and b y
deflected flows aligned toward the banks . About 1 .7 lineal miles of banks ar e
affected by erosion from currents .
The second, third, and fourth largest causes of bank erosion are humans, boat s
and animals, affecting 0 .7, 0 .3 and 0 .2 lineal miles of banks, respectively .
Human activities include camping and foot traffic from hiking and fishing .
Boat activities include boat waves and direct impacts of boats against banks .
Animal activities include foot traffic, grazing and water access .
Thus, natural causes are responsible for about 61 % of the observed erosion .
Anthropogenic causes account for only 39 % of the observed erosion, with huma n
non-boating activities responsible for about 24 %, motorboats responsible fo r
about 9 %, and grazing animals accounting for 6 % .
However, most of the identified streambank erosion is not due to only a singl e
cause . A secondary cause has increased the amount of bank erosion at som e
sites over that which would have resulted from the primary cause acting alone .
For example, high-water flows with their swifter currents and debris or ic e
loads undoubtedly have worsened the amount of bank erosion at locations wher e
other causes initiated the erosion . Similarly, foot traffic, animal use, an d
boat waves have worsened erosion at sites that were previously damaged b y
high-water flows .
In many places, potential erosion problems have been greatly limited b y
healthy, well-rooted bank vegetation . However, there are areas where suc h
vegetation has been disturbed by human and animal activities . Erosion ha s
then occurred .
Streambank erosion is most common in the lowest few miles of the Deschute s
River, near the mouth . This zone has the most intensive human activities and
local animal grazing . The next most intensive zone of human use is probabl y
near Maupin . Yet in this latter zone bank erosion is far less noticeable .
This is because more bedrock is exposed . Perhaps too, more riprap and rubbl e
has been placed along the banks for railroad construction and maintenance .
Motorboat operation is only a minor and local cause of streambank erosio n
along most of the Lower Deschutes River . However, severe erosion occurs a t
the State Recreation Area . It is due to boat mooring and wave action (eve n
though a boat speed limit is posted), compounded by natural current scour .
65
Extending upstream from this short zone is a several-mile stretch of rive r
that is heavily used for hiking, camping and fishing . Boat waves (typicall y
less than six inches high) cause inconvenience and potential hazard to peopl e
standing in shallow water . The waves also disturb loose sediment at the bank .
The loose sediment is often present due to human and animal activities . Boa t
waves are quite likely to stir up loose sediment, but not likely to erod e
tight banks, particularly if protected by vegetation . Therefore, in the man y
local areas of loose previously-disturbed sediment, boat waves do caus e
sediment agitation and an " erosion-like" effect is visible . The public thu s
gets a strong impression that motorboats and boat waves are a major proble m
and cause bank erosion .
In reaches of the river where motorboat use is prohibited, bank erosion is a s
common as in the lower 69 miles of the river . Again, natural erosion is th e
primary cause . Hence, prohibiting the use of motorboats will not halt ban k
erosion .
Overall among the causes of bank erosion, motorboat operation ranks far belo w
natural bank erosion and the erosion caused by human foot traffic, includin g
that associated with hiking, fishing, and camping . In overall impact ,
motorboat-caused erosion is roughly comparable to the erosion from anima l
access to the river and riparian grazing . But at locations where some othe r
primary cause of bank erosion has been active, boat waves disturb the sedimen t
and may be a secondary -- but perhaps more visible -- cause of erosion .
Put in perspective with all other causes of streambank erosion along the Lowe r
Deschutes River, motorboat-caused erosion is only a minor problem . Publi c
perception and public preference are likely to be more significant managemen t
concerns than any actual erosion due to motorboats . Diverse interests aboun d
among the river users . Competition for river use, fishing sites and campsites
adds to the complexity of managing the Lower Deschutes River for recreatio n
and other beneficial uses . The goals of some user groups tend to be exclusive
of the goals of other user groups . Satisfying certain goals can preempt othe r
goals and uses . If the control of streambank erosion is to be an importan t
goal, then a concerted effort is needed to simultaneously solve erosio n
problems caused by foot traffic and animals, as well as by boats .
Recommendations are made for the general control of streambank erosio n
problems in the Lower Deschutes River . These include a) monitoring the
erosion zones, b) developing a public-education effort focused on preventio n
of erosion, c) reevaluating the locations of toilets, campsites and trails ,
and d) " hardening" the assess points between the water and land i n
erosion-prone areas .
Recommendations are made for boat-wave control . These are mainly educationa l
in scope and aim at overcoming boater ignorance, indifference an d
carelessness . They involve self-imposed speed control, maintaining boat
distance from erosion-prone areas, and greater care when beaching or dockin g
against banks .
It is also recommended that immediate action by taken to halt erosion at th e
State Recreation Area . Several options are presented for doing this .
66
ANNOTETED REFERENCES
Klingeman, P . C . ; Guidelines for River Bankline Changes and . Erosion Contro l
along the Upper Deschutes River ; Draft Guidelines ; Prepared for Oregon
Division of State Lands ; Salem ; January 1989 .
This report was developed to illustrate several types of streambank change s
that are occurring along the upper Deschutes River from the LaPine Recreatio n
Area to Sunriver . An evaluation was made of existing erosion control measure s
that have been undertaken by various riparian landowners . Recommendations
were made for erosion control measures that would be compatible with thi s
environmentally sensitive reach of river . The intention of .the report was t o
provide a basis for state and county agencies to develop guidelines fo r
erosion control activities on that stretch of river . The study provides a
contrast with the present study for river conditions in the upper and lowe r
Deschutes River .
Mitchell, G . ; Motorboat Use on the Lower Deschutes River 1989 ; Oregon Stat e
Marine Board ; Salem ; December 1989 .
This report documents boating use on the Lower Deschutes River during th e
period July 1 to September 30, 1989 . Direct observations were made of jetboa t
use at three sites : Heritage Landing (RM 0+), RM 8 .5, and Macks Canyon (RM
24) . Surveys of jetboat operators were made at Heritage Landing . These
provided an extensive data base for the various statistical analyses that ar e
presented in the report . The study provides supporting documentation on th e
intensities and locations of jetboat activities that might relate to the ban k
erosion problems identified in the present study .
Shelby, B ., D . Whittaker, R . Speaker and E . E . Starkey ; Social and Ecological
Impacts of Recreation Use on the Deschutes River Scenic Waterway ; Report
to the Oregon Legislature ; State Parks Division, Oregon Department o f
Transportation ; February, 1987 .
This report summarizes field studies and survey questionnaires to identify th e
existing natural resource conditions and the social and ecological impacts o f
recreation use along the Deschutes River Scenic Waterway . Standards fo r
acceptable levels of impact were identified and evaluated, as well a s
management strategies to limit impacts and public support for such strategies .
The study provides information on past animal grazing and other activitie s
that were not directly observable in the field during the present study . Th e
study report also addresses bank erosion and makes several assumptions an d
general statements about cause-and-effect relations . But inadequat e
consideration is given to the specific river hydraulic processes and sedimen t
transport .processes that control bank erosion, so that these statements wer e
not directly useable in the present study .
67
APPENDIX A
STREAMBANI CONDITION OBSERVATIONS, BY REACH ,
FOR THE DOWER DESCHUTES RIVER
Notes :
1.
The sheets in this appendix are elaborations of the origina l
field notes to add clarity to the criptic information that wa s
recorded in the field .
2.
The main study area extends from river mile (RM) 0 to RM 69 .
This begins at the Deschutes River mouth at the Columbia Rive r
and extends upstream to the northern boundary of the Warm Spring s
Reservation . An additional reach was also examined that extende d
upstream from this Reservation boundary to RM 73 . 6
3.
All river mile designations are based on the May 1987 ODOT aeria l
photo mosaics (1 " = 400') . These appear to be consistent with th e
river mile information shown on Oregon Water Resources Departmen t
river basin maps for the Deschutes River basin and on US Geologica l
Survey quadrangle maps (7 .5-minute series) . However, they are no t
consistent with the river miles shown on the ODOT pamphlet :
" Deschutes River Scenic Waterway " .
4.
The terms " left bank" and "right bank" are based on the hydrauli c
engineering convention for all river work where the observe r
looks downstream to define the left and right banks .
REACH 1 : RM 0 .0 TO RM 1 . 0
(Source : USGS quadrangle maps )
A-2
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER :
1
RIVER MILES : From RM : 0 .0 to RM : 1 . 0
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Boulders, broken bedrock, riprap .
Broken bedrock near rapids .
Right Bank : Sandy soil over cohesive material o n
floodplain .
Broken bedrock near rapids .
Vegetative Cover :
Left Bank : brush and riparian trees
Right Bank : mixed trees and brush ; lawn in par k
Exposure to Wave
Action :
Left Bank : moderate-to-severe
Right Bank : moderate-to-severe
Near-Bank Currents : Left Bank : moderat e
Right Bank : moderate
Existing Erosion
Condition :
Left Bank : moderate (limited by 5 mph boat speed )
Right Bank : sever e
Erosion Potential : Left Bank : moderat e
Right Bank : sever e
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
At State Recreation Area park .
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
Bank sample taken from right bank @ RM 0 .7 below root zone ; sand y
soil with clay .
Mid-channel bar appears to be growing over time, pushing flo w
toward banks . Bar has shallow areas on all sides .
Typical of deposition zones where rivers enter lakes .
Boat speed limit of 5 mph protects banks from direct wave erosio n
but interaction of waves and docked boats causes damage .
REACH 2 : RM 1 .0 TO RM 2 . 0
(Source : USGS quadrangle maps )
A-4
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER :
2
RIVER MILES : From RM : 1 .0 to RM : 2 . 0
- - - - - - - - - - - - - - - - - - - - - - :
Bank Materials :
Left Bank Bedrock outcrops, mixed boulders ,
and some soil .
-
Right Bank : Bedrock outcrops, mixed boulders ,
and some soil .
Vegetative Cover :
Left Bank : sparce trees ; grasses ; brush
Right Bank : continuous trees ; grasses ; brush
Exposure to Wave
Action :
Left Bank : moderat e
Right Bank : moderat e
Near-Bank Currents : Left Bank : moderat e
Right Bank : moderat e
Existing Erosion
Condition :
Left Bank : limited ; limited-to-moderate wher e
paths reach water
Right Bank : limited ; limited-to-moderate wher e
paths reach wate r
Erosion Potential : Left Bank : limite d
Right Bank : limite d
- - - - - - - - - - - Erosion Study Sites :
- - - -
-
- - - - - - - - -
Near USGS cableway on either bank (left bank is easy to reach b y
water but right bank is not -- shallow zone) .
- - - - - Special Notes :
- - - - - - - - - - - - - - - - - - - - - - - - - -
Main footpaths parallel the river on each side, with many short sid e
trails to the water's edge .
Bank sample taken from left bank beneath USGS tower ; cohesive .
Bank sample taken from left bank 100 feet upstream of USGS tower ;
sandy soil with roots .
REACH 3 : RM 2 .0 TO RM 3 . 5
(Source : USGS quadrangle maps )
A-6
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 3
RIVER MILES : From RM : 2 .0 to RM : 3 . 5
- - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Much local bedrock ; some large boulders .
Loose boulders on floodplain .
Right Bank : Much local bedrock ; some large boulders .
Loose boulders on floodplain .
Vegetative Cover :
Left Bank : limited riparian trees
Right Bank : limited riparian trees (more than o n
left bank )
Exposure to Wave
Action :
Left Bank :
sever e
Right Bank : sever e
Near-Bank Currents : Left Bank : swift except behind rock protectio n
Right Bank : swift except behind rock protectio n
Existing Erosion
Condition :
Left Bank : limited ; local sand deposit s
Right Bank : limited ; local sand deposits ;
local erosion of exposed banks jus t
downstream of tree s
Erosion Potential :
Left Bank : limited by bedrock outcrops ; severe fo r
any loose material
Right Bank : (same note )
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
Left bank near RM 3 .5 (rocky shore with exposed tree roots) .
Right bank near RM 3 .5 (sand pocket between rock outcroppings) .
- - - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
Floodplain on left bank has overbank sand deposits .
There is extensive broken exposed bedrock in the channel .
Bank sediment sample taken from right bank @ RM 2 .1 near trees an d
campsite ; fine sand .
Sediment sample taken from right shoreline @ RM 3 .5 in shallow
water ; medium sand .
A-7
REACH 4 : RM 3 .5 TO RM 4 . 2
(Source : USGS quadrangle maps)
$7
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 4
RIVER MILES : From RM : 3 .5 to RM : 4 . 2
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Boulders and limited sand deposits .
Right Bank : Boulders and limited sand deposits .
Vegetative Cover : Left Bank : trees (1 tree wide) ; grasses ; some
exposed roots just downstream o f
Colorado Rapid s
:
trees
(1 tree wide) ; grasse s
Right Bank
Exposure to Wave
Action :
Left Bank : moderat e
Right Bank : moderat e
Near-Bank Currents : Left Bank : moderate ; swift @ rapids near RM 3 . 7
Right Bank : (same note )
Existing Erosion
Condition :
Left Bank : limited, except moderate at forme r
cattle grazing are a
Right Bank : limited, except moderate at some
campsite s
Erosion Potential : Left Bank : limited
Right Bank : limited
- - - - - - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
Former grazing area and currently used campsites show loss o f
vegetation .
REACH 5 : RM 4 .2 TO RM 5 . 1
(Source : USGS quadrangle maps )
A-10
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 5
RIVER MILES : From RM : 4 .2 to RM : 5 . 1
- - - - - - - - - - - - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Generally boulders ; quite large a t
Colorado Rapids .
More soil on boulders upstream of rapid s
than downstream of rapids .
Right bank : (same note )
Vegetative Cover :
Left Bank : trees (1 tree wide) ; brush ; gras s
Right Bank : trees (1 tree wide) ; brush ; gras s
Exposure to Wave
Action :
Left Bank : limited, except severe in Colo . Rapid s
Right Bank : limited, except severe in Colo . Rapid s
Near-Bank Currents : Left Bank : moderat e
Right Bank : moderat e
Existing Erosion
Condition :
Left Bank : limited, except severe in grazing are a
Right Bank : limited, except moderate at campsite s
Erosion Potential :
•
L eft Bank : limited, except severe in grazing area
Right Bank : limited
- - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - - - - - - - - - - - - - - - - - - - - - Special Notes :
Cattle grazing occurred earlier this year at 200 feet of left bank .
Exposed roots at right bank opposite grazing site .
Local erosion at campsites on right bank near RM 4 .7 .
Low floodplains typically contain boulders from upland slopes .
A - 11
REACH 6 : RM 5 .1 TO RM 6 . 1
(Source : USGS quadrangle maps )
A - 12
CLASSIFICATION OF STREAMBANR CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER :
6
RIVER MILES : From RM : 5 .1 to RM : 6 . 1
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Bedrock at rapids, boulders elsewhere .
Some gravel bars and high-water san d
deposits .
Right Bank : (same note)
Vegetative Cover :
Left Bank : limite d
Right Bank : limite d
Exposure to Wave
Action :
Left Bank : sever e
Right Bank : severe
Near-Bank Currents : Left Bank : moderate to swift
Right Bank : moderate to swif t
Existing Erosion
Condition :
Left Bank : limited because of extensive bedroc k
Right Bank : limited because of extensive bedroc k
Erosion Potential :
Left Bank : severe for loose material in most area s
Right Bank : severe for loose material in most area s
- - - - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
Bedrock floodplain in vicinity of rapids .
Many local "wake" deposits of sand and gravel behind boulders an d
bedrock outcroppings .
REACH 7 : RM 6 .1 TO RM 7 . 6
(Source : USGS quadrangle maps )
A-14
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 7
RIVER MILES : From RM : 6 .1 to RM : 7 . 6
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Boulders and soil ; sand deposits in
protected areas downstream of trees .
Right Bank : Boulders and soil ; some floodplain bars ;
sand deposits on floodplain .
Vegetative Cover :
Left Bank : low sparse trees ; grasses .
Right Bank : tall trees ; grasses .
Exposure to Wave
Action :
Left Bank : limited
Right Bank : limite d
Near-Bank Currents : Left Bank : moderat e
Right Bank : moderate
Existing Erosion
Condition :
Left Bank : limited ; moderate at campsite s
Right Bank : limited moderate at campsite s
Erosion Potential : Left Bank : limite d
Right Bank : limite d
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
Several campsites, particularly on left bank near Kloan .
Mid-channel gravel-cobble bar at Kloan .
Destroyed bridge piers are still in channel near Kloan .
REACH 8 : RM 7 .6 TO RM 9 . 0
(Source : USGS quadrangle maps )
A - 16
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 8
- - - - - - Bank Materials :
RIVER MILES : From RN : 7 .6 to RM : 9 . 0
- - - - - - - - - - - - - - - - - - - - Left Bank : Boulders ; gravel ; some soil .
Right Bank : Boulders ; gravel ; some soil .
Local bedrock @ RM 7 .8 .
Vegetative Cover :
Left Bank : sparce ; grass ; tall trees begin @ RM 8 . 5
and go upstream at base of steep slop e
Right Bank : sparse ; grasse s
Exposure to Wave
Action :
Left Bank : limite d
Right Bank : limited
Near-Bank Currents : Left Bank : limited-to-moderat e
Right Bank : limited-to-moderat e
Existing Erosion
Condition :
Left Bank : limited ; local eroded trails @ RN 8 . 4
lead from water to main trai l
Right Bank : limited ; locally severe near RM 8 . 5
Erosion Potential : Left Bank : limite d
Right Bank : limite d
- - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - - -
- - - - - - - - - - - - - - - - - - - - - - Special Notes :
-
-
- - - - -
Bedrock outcrop across river @ RM 7 .8 with much debris stranded a t
high-water levels .
Local severe erosion @ RM 8 .6 and 8 .4 (older, healing) appear to hav e
been caused by past high-water flows .
REACH 9 : RM 9 .0 TO RM 11 . 3
(Source : USGS quadrangle maps )
A - 18
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVER
REACH NUMBER : 9
RIVER MILES : From RM :
9 .0 to RM : 11 . 3
n
g
r
a
v
el
a
nd
b
--ou
l
d
e
r
s
;
loca
l
s a;d
Left Bank : -- Soil onear downstream end of reach .
Bank -Materials :
Right Bank : (same note )
Left Bank : sparce ; occasional trees and grasse s
Vegetative Cover :
Right Bank : sparce ; occasional trees and grasse s
Exposure to Wave
Action :
Left Bank : limite d
Right Bank : limited
Near-Bank Currents : Left Bank : moderat e
Right Bank : moderat e
Existing Erosion
Condition :
Left Bank : limite d
Right Bank : limited ; locally moderate
Erosion Potential : Left Bank : limited
Right Bank : limite d
---------------------------
-
Erosion Study Sites :
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Special Notes :
Large, heavily-used campground on flat left bank @ RM 10 .5 show s
little or no erosion .
-
y
REACH 10 : RM 11 .3 TO RM 12 . 0
(Source : USGS quadrangle maps )
A-20
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 10
RIVER MILES : From RM : 11 .3 to RM : 12 . 0
- - - - - - - - - - - - - - - Bank Materials :
Left Bank : Boulders and gravel ; local bedrock i n
rapids .
Right Bank : Boulders and gravel ; local bedrock i n
rapids .
Left Bank : trees ; brush ; gras s
Vegetative Cover :
Right Bank : trees (taller than on left bank) ;
brush ; gras s
Exposure to Wave
Action :
Left Bank : moderate
Right Bank : moderat e
Near-Bank Currents : Left Bank : moderat e
Right Bank : moderat e
Existing Erosion
Condition :
Left Bank : limited
Right Bank : moderat e
Erosion Potential :
Left Bank :
limited
Right Bank : moderate ; locally sever e
- - - - - - Erosion Study Sites :
- - - - Special Notes :
-
- - - -
- -
-
-
- -
- - - - - -
-
- -
- - - - - -
- -
- -
- - - - -
Bedrock rapids @ RM 11 .4 .
Bedrock and/or large-boulder rapids @ RM 11 .9 .
Moderate-to-severe bank erosion (loose gravel and cobbles) alon g
right bank of main channel (along a large high bar) .
A - 21
REACH 11 : RM 12 .0 TO RM 19 . 7
(Source : USGS quadrangle maps )
A - 22
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 11
RIVER MILES : From RM : 12 .0 to RM : 19 . 7
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Sizes from boulders to soil .
Local bedrock outcrop @ RM 15 .6 .
Right Bank : Sizes from boulders to soil .
Vegetative Cover :
Left Bank : grass ; low brush ; occasional tree s
Right Bank : grass ; low brush ; very few tree s
Exposure to Wave
Action :
Left Bank : limite d
Right Bank : limite d
Near-Bank Currents : Left Bank : moderat e
Right Bank : moderat e
Existing Erosion
Condition :
Left Bank : limited ; some exposed tree roots nea r
RM 1 4
Right Bank : limited ; local moderate-to-sever e
scour zone near RM 12 . 6
Erosion Potential : Left Bank : limite d
Right Bank : limite d
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
Cattle grazing along river @ RM 12 .0 - 13 .7 and also upstream .
Campsites along RM 13 .7 - 14 .5 .
Low rock wall along left bank near RM 16 .6 .
Low floodplain point bars on insides of bends .
REACH 12 : RM 19 .7 TO RM 21 . 3
(Source : USGS quadrangle maps )
A - 24
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 12
RIVER MILES : From RM : 19 .7 to RM : 21 . 3
- - - - - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Gravel ; sand ; boulders ; bedrock .
Right Bank : Gravel ; sand ; boulders ; bedrock .
Vegetative Cover :
Left Bank : trees (fairly dense) ; grasses ;
some aquatic grasses on inside of bend
Right Bank : trees (fairly dense) ; grasse s
Exposure to Wave
Action :
Left Bank : limite d
Right Bank : limite d
Near-Bank Currents : Left Bank : moderate ; strong at outsides of bend s
Right Bank : moderate ; strong at outsedes of bend s
Existing Erosion
Condition :
Left Bank : limite d
Right Bank : limited
Erosion Potential : Left Bank : limited
Right Bank : limited
- - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - -
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
Has appearance of canyon on one or both banks, depending on location .
Large gravel/cobble bars in channel with dense tree cover .
4
I!
REACH 13 : RM 21 .3 TO RM 24 . 5
(Source : USGS quadrangle maps )
A-26
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVER
REACH NUMBER : 13
RIVER MILES : From RM : 21 .3 to RM : 24 . 5
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Boulder s
Right Bank : Boulders ; cobbles and gravel on flatte r
banks .
Vegetative Cover :
Left Bank : trees (moderate) ; brush ; gras s
Right Bank : trees (moderate) ; brush ; gras s
Exposure to Wave
Action :
Left Bank : limited
Right Bank : limited
Near-Bank Currents : Left Bank : moderate
Right Bank : moderate
Existing Erosion
Condition :
Left Bank : limited ; locally moderat e
Right Bank : limited ; locally moderat e
Erosion Potential : Left Bank : limited
Right Bank : limite d
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
Erosion visible at path to toilet and nearby paths to campsites .
Deposition zone on right bank just downstream of Sixteen Canyon .
Large gravel/cobble bars in channel with dense tree cover .
Low gravel bar near RM 24 may be partly supplied from tributary .
REACH 14 : RM 24 .5 TO RM 30 . 0
(Source : USGS quadrangle maps )
A - 28
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 14
RIVER MILES : From RM : 24 .5 to RM : 30 . 0
- - - - - - - - - - - - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Bouldery ; local flat bars with boulders ,
cobbles, gravel and sand .
Very local bedrock outcrop .
Right Bank : (same note )
Vegetative Cover :
Left Bank : moderate tree cover ; extensive grass y
zone s
Right Bank : moderate tree cover ; extensive grass y
zone s
Exposure to Wave
Action :
Left Bank : moderat e
Right Bank : moderat e
Near-Bank Currents : Left Bank : moderate ; locally swif t
Right Bank : moderate
Existing Erosion
Condition :
Left Bank : limited ; many local deposition zones ;
local scour
Right Bank : limited ; many local deposition zone s
Erosion Potential : Left Bank : limited (protected )
Right Bank : limited (protected )
- - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
Many local sandy pockets .
Zones of higher erosion potential have already been riprapped t o
provide protection to railroad and road .
Many local deposition zones on bars and banks, particularly lef t
bank .
A-29
-
REACH 15 : RM 30 .0 TO RM 38 . 8
(Source : USGS quadrangle maps )
A-30
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 15
RIVER MILES : From RM : 30 .0 to RM : 38 . 8
Bank Materials :
Left Bank : Boulders ; local bedrock outcrops (mor e
than in next reach downstream) ; soil .
Low flat bars (boulders to sand) .
Right Bank : (same note )
Vegetative Cover :
Left Bank : moderate tree and grass cove r
Right Bank : moderate tree and grass cove r
Exposure to Wave
Action :
Left Bank : moderat e
Right Bank : moderat e
Near-Bank Currents : Left Bank : moderate ; locally swif t
Right Bank : moderate ; locally swif t
Existing Erosion
Condition :
Left Bank : limited ; locally moderat e
Right Bank : limited ; locally moderat e
Erosion Potential : Left Bank : limited (protected )
Right Bank : limited (protected)
Erosion Study Sites :
-
Special Notes :
A few local sand pockets .
Zones of higher erosion potential along railroad and road are alread y
riprapped .
REACH 16 : RM 38 .8 TO RM 43 . 5
(Source : USGS quadrangle maps )
A-32
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 16
RIVER MILES : From RM : 38 .8 to RM : 43 . 5
--------------------------------- Bank Materials :
Left Bank : Mixed bedrock and boulders, with bedrock
dominant .
Local pockets of cobbles and finer sed .
Right Bank : (same note )
Vegetative Cover :
Left Bank : limited grass cover ; moderate tre e
cover in non-bedrock area s
Right Bank : limited grass cover ; moderate tre e
cover in non-bedrock area s
Exposure to Wave
Action :
Left Bank : moderate to sever e
Right Bank : moderate to sever e
Near-Bank Currents : Left Bank : moderate to swift
Right Bank : moderate-to swift
Existing Erosion
Condition :
Left Bank : limited by bedroc k
Right Bank : limited by bedrock
Erosion Potential ; Left Bank : limited by bedroc k
Right Bank : limited by bedrock
---------------------------------- Erosion Study Sites :
---------------------------------- Special Notes :
Very few sand pockets, compared to next reach downstream .
REACH 17 : RM 43 .5 TO RM 45 . 1
(Source : USGS quadrangle maps )
A-34
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER :
17
RIVER MILES : From RM : 43 .5 to RM : 45 . 1
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Bedrock walls and shelves .
High floodplain sand deposits .
Right Bank : (same note )
Vegetative Cover :
Left Bank :
very sparce in most areas (grass )
Right Bank : very sparce in most areas (grass )
Exposure to Wave
Action :
Left Bank : moderat e
Right Bank : moderat e
Near-Bank Currents : Left Bank : swif t
Right Bank : swif t
Existing Erosion
Condition :
Left Bank : limited by bedrock
Right Bank : limited by bedrock
Erosion Potential : Left Bank : limited by bedroc k
Right Bank : limited by bedroc k
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
Reach includes Sherars Falls .
Reach is hydraulically equivalent to a bedrock chute .
REACH 18 : RM 45 .1 TO RH 48 . 3
(Source : USGS quadrangle maps )
A-36
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 18
RIVER MILES : From RM : 45 .1 to RM : 48 . 3
- - - - - - - - - - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Bedrock walls and ledges ; boulders ; some
bars .
White R . tributary bar (sand-to-coarse) .
Right Bank : Bedrock walls and ledges ; boulders ; some
bars .
Vegetative Cover :
Left Bank : trees, grasses, brush : extensive near
springs, moderate elsewher e
Right Bank : moderate trees, grasses, brush
Exposure to Wave
Action :
Left Bank : moderat e
Right Bank : moderat e
Near-Bank Currents : Left Bank : moderate to swif t
Right Bank : moderate to swif t
Existing Erosion
Condition :
Left Bank : limited by bedroc k
Right Bank : limited by bedroc k
local wear by foot traffic @ RM 47 . 7
Erosion Potential : Left Bank : limited by bedrock
Right Bank : limited by bedrock
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
Springs on west hillside from RM 47 .6 upstream to hatchery @ RM 47 .8 .
Road is locally protected by riprap, but bank is deteriorated b y
foot traffic @ RM 47 .7 near rapids .
A-37
REACH 19 : RM 48 .3 TO RM 52 . 0
(Source : USGS quadrangle maps )
A-38
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 19
RIVER MILES : From RM : 48 .3 to RM : 52 . 0
- - - - - - - - - - - - - - - - - - - - - - - - - - - - :
Bedrock
;
boulders
;
cobbles
;
some
soil .
Bank Materials :
Left Bank
Right Bank : Bedrock ; boulders ; cobbles ; some soil .
Sandy deposits on flat banks and i n
bank pockets .
Vegetative Cover :
Left Bank : moderate trees, grasses, brus h
Right Bank : moderate trees, grasses, brus h
Exposure to Wave
Action :
Left Bank : moderat e
Right Bank : moderat e
Near-Bank Currents : Left Bank : moderate to swif t
Right Bank : moderate to swif t
Existing Erosion
Condition :
Left Bank : limited by bedrock and ripra p
Right Bank : limited by bedrock and riprap ;
moderate in areas of heavy public us e
Erosion Potential : Left Bank : limited to moderat e
Right Bank : limited to moderat e
- - - - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
Road is locally protected by riprap .
There is heavy public use along right bank because of closeness t o
Maupin and good road access . Erosion could become worse if car e
is not taken to prevent it .
REACH 20 : RM 52 .0 TO RM 62 . 7
(Source : USGS quadrangle maps)
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 20
RIVER MILES : From RM : 52 .0 to RM : 62 . 7
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Boulders ; boulder bars ; local bedrock ;
riprap ; gravel ; sand ; soil .
Right Bank : Boulders ; boulder bars ; local bedrock ;
gravel .
Vegetative Cover :
Left Bank : moderate-to sparce grass, brush, tree s
(very dry zone )
Right Bank : moderate-to-sparce grass, brush, tree s
Exposure to Wave
Action :
Left Bank : moderat e
Right Bank : moderat e
Near-Bank Currents : Left Bank : moderat e
Right Bank : moderat e
Existing Erosion
Condition :
Left Bank : limited, except locally moderat e
Right Bank : limited, except locally moderate on bar s
with much human use (foot traffic an d
boat launching) or where flows ar e
deflected or constricte d
Erosion Potential : Left Bank : limited ; locally moderate due to flow
constrictions
Right Bank : limited ; locally moderat e
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
Heavy use by rafters and drift boats . Several launching sites .
Some alluvial fans ; natural erosion of high sand/gravel bar @ RM 57 . 2
just downstream of canyon tributary ; deflection erosion @ RM 61 .7 .
Local eroded tree roots near RM 60 and upstream .
A-41
• REACH 21 : RM 62 .7 TO RM 64 . 2
(Source : USGS quadrangle maps )
A-42
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER :
21
RIVER MILES : From RM : 62 .7 to RM : 64 . 2
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Boulders and cobbles (generally coarse) .
Right Bank : Boulders and cobbles (generally coarse) .
Vegetative Cover :
Left Bank : sparce trees and gras s
Right Bank : sparce trees and gras s
Exposure to Wave
Action :
Left Bank : moderat e
Right Bank : moderat e
Near-Bank Currents : Left Bank : swif t
Right Bank : swif t
Existing Erosion
Condition :
Left Bank : limited ; locally moderat e
Right Bank : limited ; locally moderat e
Erosion Potential : Left Bank : limited or locally moderat e
Right Bank : limited or locally moderat e
- - - - - - - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Special Notes :
This reach is a sequence of rapids and riffles .
Moderate erosion near Buckskin Mary Rapids appears to be caused b y
rafters bypassing the rapids or going back upstream to run the m
again .
A-43
REACH 22 : RM 64 .2 TO RM 69 . 0
(Source : USGS quadrangle maps )
A-44
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 22
RIVER MILES : From RM : 64 .2 to RM : 69 . 0
- - - - - - - - - - - - - - - - - - - - - - - - Bank Materials :
Left Bank : Boulders ; gravel ; soil ; local bedrock .
Right Bank : Boulders ; gravel ; soil ; local bedrock .
Vegetative Cover :
Left Bank : moderate trees and brush ; moderate-todense gras s
Right Bank : moderate trees and brush ; moderate-todense gras s
Exposure to Wave
Action :
Left Bank : moderat e
Right Bank : moderat e
Near-Bank Currents : Left Bank : moderat e
Right Bank : moderat e
Existing Erosion
Condition :
Left Bank : limited ; moderate @ RM 65 .0 due to flo w
deflection from mid-channel ba r
Right Bank : limited ; moderate @ RM 68 .9 due to flow
deflection from mid-channel bar
Erosion Potential : Left Bank : limited
Right Bank : limited
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Erosion Study Sites :
-
---------------------------------- Special Notes :
This reach has a somewhat flatter gradient than the next reac h
downstream .
Local toe erosion and collapse of railroad fill @ RM 66 .0 .
REACH 23 : RM 69 .0 TO RM 73 . 6
(Source : USGS quadrangle maps )
A-46
CLASSIFICATION OF STREAMBANK CONDITIONS ALONG THE LOWER DESCHUTES RIVE R
REACH NUMBER : 23
RIVER MILES : From RM : 69 .0 to RM : 73 . 6
-------------------------------- Bank Materials :
Left Bank : Boulders ; gravel ; soil ; local bedrock .
Some low bars and floodplain bars .
Right Bank : (same note )
Vegetative Cover :
Left Bank : moderate trees and brush ; moderate-todense gras s
Right Bank : moderate trees and brush ; moderate-todense gras s
Exposure to Wave
Action :
Left Bank : limite d
Right Bank : limite d
Near-Bank Currents : Left Bank : sluggish to moderat e
Right Bank : sluggish to moderat e
Existing Erosion
Condition :
Left Bank : limited ; locally moderate and sever e
Right Bank : limited ; locally moderat e
Erosion Potential : Left Bank : limited ; locally moderate and sever e
Right Bank : limited ; locally moderate
-
---------------------------------
-
Erosion Study Sites :
- ---------------------------------- Special Notes :
There
There
may
Local
Local
is less trampling of the banks by foot traffic than downstream .
are signs of older natural bank erosion (now inactive) tha t
have been caused by a past flood (1964?) .
natural erosion and deposition occur in tight bends .
erosion occurs at paths and campsites .
A-47
APPENDIX B
PHQ
APH RECORD ,
L(*JER DESC.HU1ES RIVER STUDY
Notes :
The river miles shown here are based on those given on the ODO T
May 1987 aerial photo mosaics . Some of these river miles do no t
exactly match the corresponding river mile locations given i n
USGS quadrangle maps . Where there are discrepancies, the ODO T
river mile location is usually about 0 .1 - 0 .2 mile downstrea m
of the USGS river mile .
RIVER MOUTH AND DESCHUTES RIVER STATE RECREATION ARE A
Reach Date Roll/Neg . RN
1
1
1
1
1
1
1
1
1
1
1
8/16/89
8/16/89
8/16/89
8/16/89
8/16/89
8/16/89
9/14/89
9/14/89
9/14/89
9/14/89
9/14/89
1/12
1/10
1/11
1/13
1/36
1/35
3/26
3/27
3/28
3/29
3/30
0. 3
0. 3
0. 3
0. 3
0.7
0.7
0. 6
0.6
0.6
0.6
0 .6
Description
View
View
View
View
View
View
Boat
Boat
Boat
Boat
Boat
U/S
U/S
U/S
U/S
D/S
D/S
bow
bow
bow
bow
bow
to Desch . R . State Rec . Area . . boats at campground
to jet boats at Heritage Landing boat ramp from hwy .
to Moody Rapids & jet boat from hwy . br .
to Moody Rapids & jet boat from hwy . br . (telephoto )
to bar and hwy . br . at mouth of Desch . R .
to bank and boats at Desch .
Rec . Area
cuts along right bank at State Recreation Are a
cuts along right bank at State Recreation Area ; near
cuts along right bank at State Recreation Area ; near
cuts along right bank at State Recreation Area ; near
cuts along right bank at State Recreation Area ; near
br .
a.
tree
tree
tree
tree
15
27
35
67
DOWNSTREAM REACHES FROM MOODY RAPIDS TO NEAR HARRIS CANYO N
Reach
Date
2
2
8/16/89
8/16/89
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
Roll/Neg . RM
Description
8/16/89
8/16/89
9/13/89
9/14/89
9/13/89
1/17
1/14
1/18
1/16
2/4
3/25
2/5
1 .5
1 .5
1 .5
1 .5
1 .6
1 .6
1 .6
Fishers and waves from D/S-bound jet boat (telephoto )
View D/S past Moody Rapids to mouth of Desch . R
Fishers and waves from D/S-bound jet boat (telephoto )
Fishers and waves from U/S-bound jet boat (telephoto )
Possible erosion study sites near USGS cableway, left bank
Possible erosion study sites near USGS cableway, left bank
Possible erosion study sites near USGS cableway, right bank
8/16/89
9/13/89
9/13/89
9/13/89
9/13/89
8/16/89
8/16/89
8/16/89
9/14/89
8/16/89
8/16/89
8/16/89
8/16/89
9/14/89
9/14/89
9/14/89
9/14/89
9/14/89
9/14/89
1/15
2/6
2/7
2/9
2/8
1/19
1/20
1/22
2/20
1/21
1/23
1/24
1/25
3/19
3/20
3/22
3/21
3/23
3/24
2 .0
2 .1
2 .9
2 .9
2 .9
3 .2
3 .4
3 .4
3 .4
3. .4
3 .4
3 .4
3 .4
3 .5
3 .5
3 .5
3 .5
3 .5
3 .5
View U/ S
East bank hikers' campsite, showing bank erosio n
Boat stuck on rocks at D/S end of Rattlesnake Rapids .; view U/ S
Paul Donheffner and Gene Owens ready to help boat stuck on rock s
Boat stuck on rocks at D/S end of Rattlesnake Rapids ; view U/ S
View U/S to fishers using jet boat for acces s
View U/S to 3 jet boats, 1 going U/S and 2 going D/S
Jet boat coming U/S
Typical local sandy deposit behind rocks ; left bank
Jet boat and waves at sandy beach
Jet boat waves at rocky point D/S of sandy beach ; high-water sand deposit s
Jet boat waves at sandy beach
Jet boat waves at sandy beach
Possible erosion study sight, right bank ; view D/ S
Possible erosion study sight, right bank ; U/S reference spot on rocks
Possible erosion study sight, right bank ; D/S reference spot on rocks
Possible erosion study sight, right bank ; sand ripples from waves
Possible erosion study sight, left bank ; example of boulders protecting ban k
Possible erosion study sight, left bank ; example of boulders protecting ban k
B- 2
DOWNSTREAM REACHES FROM MOODY RAPIDS TO NEAR HARRIS CANYON, continue d
Reach
-----
Date
4
4
4
4
9/14/89
9/14/89
8/16/89
Roll/Neg . RN
Description
8/16/89
3/18
2/21
1/27
1/26
3 .9
4 .2
4 .2
4 .2
Bouldery right bank
Typical sand deposit behind rocks, eroded by waves ; left bank D/S of Colo . Rapids
View D/S past Colorado Rapids
Drift boats at Colorado Rapids
5
5
5
5
5
8/16/89
9/13/89
9/14/89
9/13/89
8/16/89
1/28
2/10
2/22
2/11
1/29
4 .2
4 .7
4 .9
4 .9
4 .9
View U/S
Local erosion at campsite on right bank in Lot 1, Section 1 1
Cattle grazing zone on left bank (in am )
Cattle grazing zone on left bank (in pm )
Cattle grazing zone seen from upstrean opposite bank
6
6
6
6
6
6
9/13/89
8/16/89
8/16/89
9/14/89
9/14/89
9/13/89
2/12
1/30
1/34
3/16
3/17
2/13
5 .5
5 .5
5 .8
5 .7
5 .7
6 .1
Exposed gravel on left ban k
View U/S to Gordon Ridge Rapids ; rocky bends and "wake" sand bar s
Rafts at Gordon Ridge Rapids
Bedrock outcrop on right side of Gordon Ridge Rapids ; high sand deposit s
Bedrock outcrop on left side of Gordon Ridge Rapids ; high sand deposits
Fisherman on Sharps Bar, right bank, with high sand deposits
7
7
7
9/13/89
9/13/89
9/14/89
2/14
2/15
2/23
6 .3
7 .0
7 .0
Campsite on left bank (in pa )
Campsite on left bank (in pm )
Campsite on left bank (in am )
8
8
8
8
8
9/13/89
9/14/89
9/13/89
9/13/89
9/13/89
2/16
2/24
2/18
2/19
2/17
8 .0
8 .0
8 .4
8 .5
8 .6
Campsite on right bank (in pm )
Campsite on right bank (in an )
Erosion along right bank
Erosion along right bank and exposed tree roots at campsit e
Erosion along right bank
9
9
9
9
9
9
9
9
9
9/14/89
8/16/89
8/16/89
9/14/89
9/14/89
9/14/89
8/16/89
9/14/89
9/14/89
2/25
1/31
1/32
3/15
3/14
3/13
1/33
3/12
3/11
9 .2
9 .4
9 .4
9 .5
10 .0
10 .4
10 .7
11 .0
11 .1
High-water sand deposits on left bank
Jet boat going D/ S
Resulting waves fro' jet boat going D/ S
View U/S at sparce vegetation along left ban k
View D/S across low bouldery point bar on left ban k
View U/S to Steve Koeller's camp site on left ban k
View D/S to campground ; waiting for rafters to arriv e
Grass and sage along right bank ; public outhouse
Grass and sage along right ban k
10
9/14/89
3/10
11 .8
Right bank eroded by high waters
LOWER-MIDDLE REACHES FROM NEAR HARRIS CONYON TO HACKS CANYON CAMPGROUND
Reach
Date
11
11
11
11
11
11
11
9/14/89
9/14/89
9/14/89
9/14/89
9/14/89
9/14/89
9/14/89
3/9
3/8
2/26
3/7
2/27
3/6
2/28
12 .4
13 .5
14 .9
16 .0
17 .6
17 .7
19 .0
Gravel bar at mouth of Harris Canyon ; right bank
Low grassy point bar on right bank
Exposed tree roots on left ban k
Natural high-water erosion along left ban k
Cattle grazing on right ban k
Typical grassy banks in this reach ; right bank shown
Cattle access to water on right ban k
11
11
12
12
12
12
9/14/89
9/14/89
9/14/89
9/14/89
9/14/89
9/14/89
3/5
3/4
3/3
3/2
3/1
3/0
19 .2
19 .5
20 .1
20 .1
20 .3
20 .6
Limited bank vegetation along right ban k
Limited bar and bank vegetation along left bank
Dense vegetation on left bank at inside of ben d
Basalt outcrop on right bank at outside of ben d
View U/S to well-vegetated mid-channel bars/island s
View D/S to well-vegetated mid-channel bars/island s
12
13
13
13
13
9/14/89
9/14/89
9/14/89
9/14/89
9/14/89
2/29
2/30
2/31
2/32
2/33
20 .7
22 .3
22 .3
22 .3
22 .5
Dense vegetation on bars and banks ; view D/ S
Local bank wear from boaters/campers using tiolet on left ban k
Local bank wear from boaters/campers using left bank
Local bank wear from boaters/campers using left bank
Erosion on right bank due to river scour at high wate r
13
13
13
13
13
9/14/89
9/14/89
9/14/89
9/14/89
9/14/89
2/34
2/35
3/-0
2/36
2/36A
22 .9
22 .9
24 .3
24 .5
24 .5
View U/S to well-vegetated
View U/S to well-vegetated
View D/S to well-vegetated
BN RR line along left bank
BN RR line along left bank
Roll/Neg . RM
Description
mid-channel bars/island s
mid-channel bars/island s
mid-channel bars/island s
at Racks Canyon campgroun d
at Hacks Canyon campground
UPPER-MIDDLE REACHES FROM MACES CAMPGROUND TO NAUPIN
Reach
Date
14
14
14
9/15/89
9/15/89
9/15/89
3/31
3/32
3/33
26 .1
26 .3
29 .0
Bank erosion and tree root erosion D/S of Ferry Canyon alluvial fan on left bank
Deposition zones behind rocks along left ban k
Stranded dead trees and aquatic plants along left bank
15
15
9/15/89
9115/89
3/34
3135
30 .2
35 .6
Erosion zone along left bank due to high-water flow and local footpaths
Erosion of D/Send of bar deposit ; probably due to high-water flow s
16
16
16
16
16
16
8/16/89
8/16/89
9/15/89
9/15/89
9/15/89
9/15/89
1/8
1/9
4/1
4/0
4/-0
3/36
39 .9
39 .9
39 .9
41 .0
41 .0
41 .8
View U/S from north
View D/S from north
Our drift boat near
Our drift boat near
Our drift boat near
Our drift boat
17
17
17
17
17
17
8/16/89
8/16/89
8/16/89
8/16/89
9/15/89
9/15/89
1/4
1/5
1/6
1/7
4/3
4/2
44 .2
44 .2
44 .0
44 .0
44 .0
44 .1
View D/S to Sherars Falls
View D/S to Sherars Falls (telephoto )
Fishing platforms and fish ladder at Sherars Fall s
Fishing platforms at Sherars Falls
Fishing platforms and fish ladder at Sherars Fall s
Steeppass fish ladder and tagging station at top of ladde r
18
18
8/16/89
8/16/89
1/2
1/3
46 .5
46 .4
View across to mouth of White R . from east bank of Deschutes R .
View U/S to mouth of White R . from east bank of Deschutes R .
19
19
19
9/15/89
8/16/89
8/16/89
4/4
1/1
1/0
49 .9
51 .5
52 .0
Well-grassed bank in _good condition near Handicapped-Use fishing pie r
View U/S to Deschutes R . Hwy . 197 br . at Maupin
View D/S to Deschutes R . Hwy . 197 br . at Maupin
Roll/Neg . RM
Description
side of . "saddle" road near RR tunnel
side of "saddle" road near RR tunne l
bridge at D/S end of RR tunne l
bridge at U/S end of RR tunne l
bridge at U/S end of RR tunne l
UPSTREAM REACHES FROM MAUPIN TO WARN SPRINGS RESERVATION BOUNDAR Y
Reach Date Roll/Neg . RN
Description
Erosion of flood deposits by high-water .flows ; right bank D/S of alluv . bldr . fan
.Right-bank erosion caused by diagonal channel flow s
Right-bank erosion caused by diagonal channel flow s
20
20
20
9/15/89
9/15/89
9/15/89
4/5
4/7
4/6 :
57 .1
61 .7
61 .7
21
21
21
9/15/89
9/15/89
9/15/89
4/8
4/9
4/10
63 .4
63 .7
63 .7
Log debris caught against tree s
BLM trail on bank around Bucskin Mary Rapids (Dant Chute) ; right bank
BLM trail on bank around Bucskin Mary Rapids (Dant Chute) ; right bank
22
22
22
22
22
22
22
22
22
22
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
4/11
4/12
4/13
4/14
4/36
4/15
4/16
4/35
4/34
4/33
65 .0
65 .8
65 .8
66 .0
66 .8
67 .0
67 .7
68 .3
68 .3
69 .0
Natural erosion of left bank due to shifting channel alignment ; view upstream
Erosion from loss of debris darn, followed by BLM erosion control ; right bank '
Erosion fron loss of debris dam, followed by BLM erosion control ; right bank
Slump of railroad fill on left bank
View U/S to eroded cliffs and talis slopes on right side of rive r
Eroded cliffs and talis slopes on right side of rive r
Campsite on right bank
Archimedes Screw" at ranch on right bank
Archimedes Screw" at ranch on right bank
Sign at Reservation Boundary : "no motorboats upstream of this sign "
REACH IN WARM SPRINGS RESERVATION
Reach Date Roll/Neg . RN
23
23
23
23
23
23
23
23
23'
23
23
23
23
. 23
23
23
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
9/15/89
4/32
4/17
4/18
4/19
4/31
4/20
4/21
4/22
4/23
4/30
4/24
4/29
4/25
4/26
4/27
4/28
69 .3
69 .6
70 .2
70 .4
71 .0
71 .5
72 .0
72 .6
72 .6
72 .6
72 .8
73 .0
73 .5
73 .6
73 .5
73 .5
Description
Erosion along left bank in short ben d
View U/S to mid-channel bedrock outcro p
Erosion along right bank in series of short bend s
Recovery of eroded right bank after cattle exclosur e
Eroded path and downed tree on left bank at Hard y
Older high-water erosion of right bank ; now behind low ba r
Erosion fron bank access use D/S of tree
Wear on right bank D/S of RR bridge-due to boater us e
Wear on right bank D/S of RR bridge due to boater us e
View D/S to a' bridge at North Junction (Davidson )
Left-bank erosion by currents and eddies below rapids in tight, complex bend .
Rubble/rock, at right bank in short narrow subreach
Eddy erosion of right bank D/S of tight bend at Davidson Fla t
Sharp point at Davidson Flat on inside of tight ben d
Exposed tree roots just D/S of point on Davidson Fla t
Exposed tree roots just D/S of point on Davidson Flat ; beaver gnaw marks
Note : RN is based on ODOT May 1987 aerial photo mosaic s
APPENDIX C
BOAT-WAVE EROSION ;
B TRF LITERATURE REVIEW
OVERVIEW
Water-oriented recreation has become a major issue in the management of rive r
use in the past two decades . Power-boating, a traditional river activity, no w
must compete with other recreational activities for river use . The pressur e
for available space on and along the river and a heightened sensitivity to th e
" quality " of river experiences contributes to recreational conflicts .
A limited and rather general body of literature is
problems caused by boats . Specific information of
on waves, waterway design and related requirements
are given limited treatment . A review was made of
literature . It is summarized in this appendix .
available about the erosio n
a hydraulic nature focuse s
. General erosion impact s
the readily availabl e
METHODS FOR IDENTIFYING RIVER RECREATION BOATING IMPACTS
Jaakson (1988) presents a method to identify and measure the impacts o f
recreational boating in a river . His work was part of management pla n
development for the Rideau River in Ontario, Canada, a meandering river wit h
limited sightlines . Vessels using this waterway included runabouts, cruisers ,
houseboats, water-skiers, canoes and kayaks .
Four measurement variables were identified : vessel speed ; boat lanes used ;
wake features ; and boat operational characteristics .
Vessel speed accounted for a significant part of boat impact, particularly i n
narrow river reaches . Visibility on the river was found to be an importan t
related variable . Speed was divided on the basis of water-skiing speed int o
the catagories of slow (under 19 mph) and fast .(over 19 mph) .
Imaginary lanes of boat traffic can be visualized in river channels withou t
buoys . The number of such lanes depends on the channel width, depth ,
currents, visibility and features of river banks . The number of availabl e
lanes that a boat uses was quantified . For example, a jetboat in a hurry use d
only one lane while a boat with a water-skier used up to three lanes in th e
study area .
Wake characteristics are complex . They involve height, steepness, speed, an d
distance of travel . These depend on vessel hull shape, displacement, draft ,
length and speed . Wake was categorized as small (one that does not reach th e
shore from mid-channel) or large (wakes that reach the shore) .
When a boat changes from moving in one direction parallel to the shore (i .e . ,
running upstream), other boats may need to take corrective actions . These
operational characteristics include coming to a full stop in the river an d
making U-turn maneuvers .
Every boat was found to have some impact, but the degree of impact varied .
The impact was subjective . For comparison, impact scores were assigned fo r
different conditions within the four variables used . The impacts wer e
affected by the shape of the river, including sharp bends, high banks, an d
limited sightlines .
The management plan attempted to accomodate a wide diversity of boatin g
activities . It sought to reduce the adverse effects of high-impacting boats .
These use a large water area and reduce the diversity of boats by displacin g
the impacted boats . This goal was eventually achieved by setting a spee d
limit for all boats and through other actions .
FORMATION OF WAVES BY SHIPS
The literature on wave formation and wave characteristics is mainly based o n
large vessels . Much of it also appears to be applicable for smaller boats . A
brief summary follows .
Formation of Ship Waves
Bhowmik et al . (1982) and Sorensen and Weggel (1984) offer basic explanation s
for how waves are formed by a ship . As a vessel moves on or near the fre e
surface of a water body, it generates a disturbance in the flow field . The
flow around the hull of the vessel is accelerated due to changes both i n
magnitude and direction . The flow in front of the bow is decelerated until i t
reaches the stagnation point at the bow because of the blockage of the flo w
area by the vessel . These accelerations and decelerations result i n
corresponding changes in pressure and, thus, water level elevation . In area s
where the flow is accelerated, the pressure and water level elevation drop ,
and vice versa . Thus, as water flows past the bow of ship, a pressur e
gradient develops and waves are generated . The pressure gradient an d
resulting height of wave are a function of relative water velocity, bow shape ,
and ship draft .
Waves are generated at the bow, stern, and any other points where there ar e
abrupt changes in the vessel ' s hull geometry that cause disturbance in th e
flow field . As the vessel moves forward with respect to the water, the energ y
transferred to the water from the vessel generating the disturbance is carrie d
away laterally by a system of diverging and transverse waves . The divergin g
waves move obliquely out from the sailing line . The transverse waves move i n
the direction of the sailing line .
Deep-water wave crest pattern generated by ship's bo w
(Sorensen and Weggel, 1984 )
C - 3
Since waves are generated both at the bow and stern of a vessel, they interac t
with each other at some disci'nce from the vessel . The transverse waves mee t
the diverging waves on both hides of the vessel along two sets of lines calle d
cusp lines . For a point disturbance moving at a constant velocity in a n
initially still, deep, and f*ictionless fluid, these form an angle of slightl y
more than 19 degrees with the sailing line . Thus, the cusps are located alon g
lines about 20 degree out from the sailing line . If the ship speed i s
increased, this pattern retains the same geometric shape but grows in size a s
the wave lengths increase .
At increasing distances from the bow, diffraction causes the wave crest lengt h
to increase and the wave amplitude to decrease . Wave heights at the cus p
points decrease at a rate inversely proportional to the cube root of th e
distance from the bow . The transverse wave heights along the sailing lin e
decrease at a rate inversely proportional to the square root of the distanc e
from the bow . Thus, at greater distances from the ship, the diverging wave s
become more prominent than the transverse waves .
In deep water, where (depth) > 0 .5 (wave length), the wave height generall y
Increases with increasing velocity, except at certain velocities where the bo w
end stern waves cancel each other . Then the wave height decreases wit h
increase of distance from vessel . This means that the total energy per wav e
is distributed over a larger area .
In shallow water where (depth) < 0 .5 (wave length), the water particle motio n
generated by waves will reach the bottom and the wave pattern will chang e
significantly . The depth Froude number, Fd, is the important parameter i n
shallow water and is the vessel velocity divided by the square root of th e
product of gravitational acceleration and water depth . Based on experiments ,
at Fd = 0 .4 the waves will reach the bottom . As Fd increases, with an
increase in vessel velocity or a decrease in depth, the diverging waves rotat e
forward and finally make a right angle with the sailing line at Fd = 1 .0 . A t
Fd = 1 .0 the diverging and transverse waves form a single wave which travel s
with the same speed as the vessel .
Development of Ship Wave Design Informatio n
Sorensen and Weggel (1984) presented results of efforts to develop genera l
ship wave prediction methods for designers . Based upon available data, a shi p
wave height predictor model Was developed that gives the maximum ship wav e
height . Ship wave characteristics (heights, periods, crest orientations )
depend on water depth, distance from the sailing line, ship speed, ship hul l
form, ship draft, and ship displacement . Knowledge of the ship wav e
characteristics is required for the design of various waterway features, such
as bank erosion control structures and marina protective works, as well as fo r
the establishment of allowable ship speed .
Surges and Waves Generated bi Ships in Constricted Channel s
Bhowmik et al . (1982) note that for narrow channels a complex flow conditio n
and wave pattern will result .' Waves generated by moving vessels will b e
relatively higher than those generated in unrestricted waters . This is due t o
significant reduction in the flow area and associated higher accelerations o f
flow around the vessel . If he channel is also shallow, the combined effec t
will result in an even more complex flow condition and higher wave heights .
C-4
tot
Herbich and Schiller (1984) reported on a study of surges and waves along th e
Sabine-Neches waterway in East Texas . Bank erosion was occurring . It was
thought to be principally caused by ship traffic generating surges and waves .
This study evaluated the magnitude of surges and waves by ships, as well a s
the bank erosion potential . Recommendations were also given for the mos t
economical structural measures to prevent bank erosion .
In constricted channels, ships caused surges that moved perpendicularly to th e
bank at a high velocity, causing bank erosion . Bow and stern waves wer e
generated by the ships, but these were of small magnitude compared with th e
surges . Small boats and tugs generated only insignificant surges bu t
generated waves which are of high magnitude .
II
II
I,~ I
Iw~'~ I
Shallo w
W .zer
II
f rh
Shallow
Slara r
II
r
Figure 1 . Dredged Ship Channel
Figure 2 . Waves and Surges Generated by a Ship in a Constricte d
Channe l
Waves and surges generated in a constricted channel by a shi p
(Herbich and Schiller, 1984 )
Field experiments showed that the surge height is a function of the ship' s
Froude number and draft and that it increases rapidly with Froude number . Th e
Froude number is defined as the vessel's speed divided by the square root o f
the product of gravitational acceleration and vessel draft .
For large vessels, the experiments showed that the surge height generated i s
considerably higher than the waves generated by such vessels .
For small vessels, the experiments showed that the waves generated ar e
principally a function of ship's speed . It was also concluded that the wav e
heights generated by small vessels are very large in comparison with surge s
generated by such vessels . In fact, surges in these cases can be considere d
insignificant .
FORMATION OF WAVES BY SMALL MOTORBOATS
Sudol'skii (1986) presents information about the amount, intensity, and th e
regimes of movement of small motorboats on various bodies of water, includin g
the dimensions of boat waves formed . Information is from Soviet research an d
observations of motorboat effects on reservoir shores and bottoms .
Investigations of motorboats showed that transverse waves formed behind th e
sterns and diverging waves left the sides roughly at a 20 degree angle to th e
boat's long axis .
The following theoretical points were confirmed by measurements :
1 . Ratio between lengths of diverging and transverse boat waves is :
(length of diverging waves) = 0 .67 (length of transverse waves) .
2. Rate of propagation of transverse boat waves in deep water is equal t o
boat speed .
3. Largest boat waves are formed with Froude numbers close to one .
4. Heights of diverging and transverse waves decrease exponentially wit h
increasing distance from the boat .
5. Periods of boat waves are defined with sufficient accuracy by ripple-typ e
wave periods .
6. for a small motorboat moving at high speed, a so-called " hydroplane "
regime sets in, in which boat waves do not form, since they reach maxima l
curvature and are destroyed by the boat hull immediately .
Motorboats were found to have several hydrodynamic effects . They stirred u p
the bottom sediments by wave action and by boat-induced flows . They als o
caused erosion of above-water banks .
The degree of hydrodynamic effects of small motorboats was found to increas e
with (a) increased boat wave size and number of passing boats, (b) decrease d
waterway size and depth, and (c) decreased resistance of the soils to erosion .
Experiments showed that the heights of diverging boat waves formed by movin g
motorboats increased from near-zero values when the speed of the boat is abou t
2 .25 mph to 0 .65 - 1 .0 foot with speed of about 6 .7 - 10 mph . With motorboat
speed greater than 10 mph (Froude number >1) wave height decreases . Boat
waves reached heights of 1 foot most often in channels of small width wit h
steep underwater slope (over 6 degrees) and boat speed of 6 .7 - 10 mph . I n
waterways 130 - 165 feet wide with mild underwater slopes, the height o f
greatest boat waves was usually 0 .65 - 0 .82 foot .
The information obtained indicated that to ensure the smallest possibl e
hydrodynamic effects of small motorboats on the bottom and shores of waterway s
and reservoirs, it is advisable to keep boat speed below 3 .3 mph or in a
hydroplane regime . In small waterways and channels with limited depths (les s
than 5 feet), it is preferable to consider the movement of small motorboats i n
a hydroplane regime .
BOAT TRAFFIC, SEDIMENT RESUSPENSION AND TURBIDITY
Garrad and Hey (1987) discuss the relation of boat traffic to turbidity an d
algal growth in the Norfolk Broads, England . They demonstrate how th e
resuspension of bed sediments by a single moving boat is possible, and how th e
diurnal variation of boat traffic movement has distinct effects on patterns o f
suspended sediment concentration and hence turbidity .
Algal growth had long been thought to be largely responsible for the hig h
turbidity levels in the broadland waterways . Examination of the suspende d
sediment concentration patterns after the passage of a boat suggest that boa t
traffic can also be responsible, by putting material into suspension an d
increasing turbidity in the water column . The effect varies for differen t
boat types . Some are capable of increasing the concentration of suspende d
material to a greater degree than others .
The diurnal pattern of the suspended sediment at navigable sites appeared t o
reflect boat traffic movements . Larger variations in concentration occurre d
in sections with higher speed limits . No such variation was found at th e
non-navigable sections . Thus, it is likely that boats were a significan t
factor in suspended sediment concentration and turbidity on a daily basis .
A reappraisal of managerial policies was recommended to take into account th e
effect of boat speed and frequency, if there were to be an effective recover y
of the Broadland waterways and protection of the river banks against furthe r
erosion .
WAVES GENERATED BY RIVER TRAFFIC AND WIN D
Bhowmik et al . (1982) reported on a study to collect data on waves generate d
by river traffic and winds on the Illinois and Mississippi rivers and t o
determine the waves characteristics for different types of vessels . Th e
similarities and dissimilarities between boat waves and those produced b y
natural effects, such as wind, were also investigated . Along some reaches o f
the Illinois River, it is estimated that 75Z of the banks were being eroded b y
waves generated by river traffic and wind .
The wave patterns generated by various type of vessels were found to b e
significantly different . The wave peaks and troughs and the wave durations
were changed by changing the vessels type .
The maximum measured wave heights ranged from 0 .1 to 1 .08 feet . An
empirical equation was developed to better predict the measured wave heights .
By using a multivariable regression analysis between the measured maximum wav e
heights and the important parameters which were felt to influence th e
generation of waves, the following equation was introduced :
H max/D = 0 .133 (FD )
where
FD = V/sqrt(gD) = draft Froude numbe r
H = wave heigh t
D = draft of the vessel .
In general, the observed and calculated waves generated by river traffic wer e
found to be significant enough to cause stream bank erosion on both th e
Illinois and Mississippi rivers . The obtained equation for predicting wav e
heights showed better correlation with measured wave heights than th e
previously existing equations .
. The wave heights for wind-generated waves were also calculated in this study .
Their magnitudes were found to be larger and their durations longer than thos e
of river traffic, even though significant wind generated waves do not occu r
every day .
REFERENCES
Bhowmik, N . G ., et al . ; Waves Generated by River Traffic and Wind on th e
Illinois and Mississippi Rivers ; Water Resources Research ; Report No . 167 ;
University of Illinois ; March 1982 .
Garrad, P . N . and R . D . Hey ; Boat Traffic, Sediment Resuspension and Turbidit y
in a Broadland River ; Journal of Hydrology ; Vol . 95 ; 1987 .
Herbich, J .B . and R . E . Schiller ; Surges And Waves Generated By Ships in a
Constricted Channel ; Journal of Coastal Engineering ; Vol . III ; 1984 .
Jaakson, Reiner ; River Recreation Boating Impacts ; Journal of Waterway, Port ,
Coastal and Ocean Engineering, American Society of Civil Engineers ; Vol . 114 ,
No . 3 ; May 1988 .
Sorensen, R .M . and J . R . Weggel ; Development of Ship Wave Design Information ;
Journal of Coastal Engineering ; Vol . III ; 1984 .
Sudol'Skii, A . S ; Formation of Waves and Boiling of Bottom Sediments By Smal l
Motorboats ; Soviet Meteorology and Hydrology ; No . 3 ; 1986 .
APPENDIX D
ST
t
DATA FM EROSION STUDY SITE
AT 1NZSCHOTES RIVE SPATS
CRI AREA
D-1
to?
bouts - S
ec}l 'Of
b(4
C
Sc
O. Ad
pe„
e
S f'`P k
s1 IN
I.
sv .'"!cl e
cap Z.
FIGURE D-1 . AERIAL VIEW AND SKETCH OF EROSION STUDY SITE
(Source : ODOT May 1987 aerial photo mosaic )
D-2
Reference Water Surface Elevation for Observation s
Date of observations : September 14, 1989
Reference location : Water surface elevation at staff gage o n
upstream side of east pier of state highwa y
bridge .
Reference elevation : 59 .05 feet, reservoir datum .
Note : this may actually be 159 .05 feet, mean sea level ,
since the normal pool elevation of Celilo Lake i s
about 160 feet, according to USGS 7 .5-minute map
for Wishram quadrangle .
Example of Near-bank River Depth s
Observations are based on range-pole measurements made from a boat movin g
across the river channel on the east side of the large mid-channel ba r
between that bar and the east bank of the river .
-r
rive r
bank
3 .3 - 3 .5 fee t
2 fee t
6 feet
2 .8 fee t
3 .0 - 3 .5 feet
over a larg e
width
4 .0 feet i s
maximum depth
PLAN-VIEW POSITION OF BANK WITH RESPECT TO FIXED FEATURES IN PAR K
Reference Location
for Measurement to Bank
or for Alignment to Bank
Distance Bank Water Depth, feet
-
to Top Height, --of Bank, feet
at bank 1 .5 fee t
from bank
feet
Trees are south of line extended to water from irrigation control box .
Irrigation control box in lawn
77 .8
3 .1
0.5
0.7
Sprinkler cap 3 and extended bank
48 .8
2 .3
0 .4
1 .0
Sprinkler cap 3 and tree near bank
43 .8
2 .8
0 .4
0.5
Sprinkler cap 2 and 5 mph sign
40 .8
2 .8
0 .4
1 .0
Sprinkler cap 1
41 .4
3 .4
0.9
1 .7
Boat cross section of channel and bank sample taken at tree 1 .
West face of tree 1
14 .5
3 .0
0 .9
1 .7
Center of pipe cap 1
16 .0
3 .0
1 .4
2.1
West fence at tree 9
9 .8
3 .1
0 .4
1 .1
16 .3
3 .1
0 .5
1 .3
Root and west fence at tree 14
Boat cuts in bank begin at tree 15 .
Base of west fence at tree 21
12 .9
2 .5
0 .5
1 .2
= 3 .1 from upper level
3 .3
0.2
West fence at root of tree 27 4 .8
+ 0.1
(beach)
West fence over end of root of tree 41
10 .2
2 .7
+ 0.5
0 .8
(beach)
West fence and root of tree 65
9 .7
1 .3
+ 0 .4
(4 .5 ft .
= 2 .7
(beach) to water )
from upper level
Much local bank collapse between trees 41 and 65 .
West edge of base of tree 68
24 .0
2 .5
0 .1
0.2
West edge of base of tree 75
28 .0
2 .7
0 .2
0 .3
North of tree 75, trees bend away from bank line .
A brush-and-marsh zone begins at tree 82 and extends north to road fill .
* Descriptions begin at south end of measurement zone and end at north end .