SCOTT RIVER RIPARIAN VEGETATION
ASSESSMENT
1.0
Study Goals and Objectives
The evaluation of riparian vegetation on selected reaches of the Scott River has two principle
goals:


Characterize current riparian vegetation conditions
Identify potential opportunities for restoring and/or enhancing the ecological functions of
riparian vegetation
Specific study objectives include:





2.0
Determine the present distribution of riparian vegetation (total vegetation canopy cover).
Sample the species composition and structure of riparian vegetation
Identify environmental and land use constraints affecting the distribution and condition of
riparian vegetation
Identify locations where restoration and/or enhancement of riparian vegetation may
provide benefits such as increased stream shading, reduced sedimentation, and
improved bank stability
Determine canopy height, width, offset, and density of riparian vegetation for use in
water temperature models
Existing Information/Literature Review
There have been several studies of riparian vegetation associated with the Scott River and its
tributaries. Included among these are studies assessing the potential for restoration, as well as
modeling the benefits of riparian restoration and enhancement in moderating stream
temperature (Lewis 1992, Watershed Sciences 2004, Kennedy et al. 2005, and NCRWQCB
2005). Kennedy et al. (2005) report a total of 2,290 acres of riparian habitat out of 519,680
acres in the Scott River watershed, about 0.5 percent of the total area (Table 1).
Table 1. Riparian Vegetation Types in the Scott River Watershed (Kennedy et al. 2005)
CalVeg Vegetation Type
Acres
Wet Meadows (Grass/Sedge/Rush)
702.6
Willow
540.9
Mountain Alder
449.9
Mixed Riparian Hardwoods
268.1
Willow Riparian Scrub
233.6
White Alder
61.4
Quaking Aspen
28.7
Black Cottonwood
4.4
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Total
2289.6
The Willow vegetation type includes areas planted with the exotic golden willow that was
introduced to the watershed for erosion control in the 1950’s.
Lewis (1992) evaluated riparian vegetation in the Scott River watershed for the Siskiyou
Resource Conservation District. The scope of the work included the inventory and evaluation of
the riparian system on 30 river miles between seven miles southeast of Etna to eight miles
northwest of Fort Jones. Among other parameters, Lewis collected data at 373 identified sites
on dominant species age, crown density of overstory species and percentage or diversity of
understory cover. Lewis classified one percent of his sampled stands as “pristine”. Pristine was
defined as “two or more dominant species averaging 25 to 30 feet in height with 90 percent to
100 percent crown density; 85 percent to 95 percent shading and/or overhang of low flow at toe
of bank slope; no apparent dieback of dominant species; age 20 years or more; livestock
excluded” (Lewis 1992). Lewis rated over 50 percent of his sampled sites as “good”. Good was
defined as “one or two dominant species, averaging 8 to 20 feet in height, with 65 percent crown
density. Stream shading averaged 48 percent”. By inference, nearly half of Lewis’s sampled
sites were rated as less than good. Lewis’s work included evaluation of potential restoration
and enhancement practices for specific properties along the mainstem. Parties that eventually
will conduct the riparian assessment on the Scott River should consult his extensive mapping
and characterization of conditions along the river.
Additional studies of riparian vegetation in relation to groundwater, soils, and potential
restoration include Mack (1958), Watershed Sciences (2007), Foglia et al. (2013a), Foglia et al.
(2013b), and Harter and Hines (2008).
Appendix A presents images displaying typical riparian conditions along the Scott River.
3.0
Study Areas
Current plans are to conduct riparian assessments on selected reaches on the Scott River
watershed utilizing remote sensing data and limited fieldwork. The Scott River watershed is
about 812 square miles at the confluence, and about 650 square miles at the USGS streamflow
measurement station (gage) at Fort Jones. During project scoping, the Scott River was
segmented into study reaches using criteria such as hydrology, length, geomorphology, and
others (Normandeau Associates 2013; Figures 1 and 2). The study areas for proposed for
riparian vegetation assessment are presented in Table 2 (see Scott River Potential Studies
Matrix; http://www.normandeau.com/scottshasta/project_materials.asp).
Table 2. Riparian Assessment Reaches in the Scott River Watershed. Reach location numbers
refer to identification codes in Figures 1 and 2.
Reach Location
Length
(miles)
Riparian Conditions and
Constraints
References
Studies
Status
Shackleford/Mill to
Oro Fino Creek (2)
7.3
2.4
CDFG 2003, 2009;
Jopson 1995, 1996;
Kennedy et al.
2005; Lewis 1992;
Partial
Oro Fino Creek to
Riparian vegetation varies from
moderately sized patches or
galleries to non-existent. No
continuous corridors. Channel
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Moffett Creek (3)
entrenchment limits access to
floodplains and allows only
narrow bands of riparian
vegetation in many areas.
Restoration efforts have had
mixed results. Riparian fencing is
present for the majority of the
mainstem.
NMFS 2012;
NCRWQCB 2011;
SRWC 2006; SRCD
2001
Partial
Moffett Creek to Etna
Creek (4)
8.5
Etna Creek to French
Creek (5)
5.8
French Creek to Lower
Tailings (6)
3.4
Lower Tailings to East
Fork/South Fork
Confluence (7)
4.7
Lower East Fork (EF1)
5.5
Upper East Fork (EF2)
To be
determ
ined
Lower Etna Creek
(ET1)
4.5
Middle Kidder Creek
(KD1)
6.6
Lower
Kidder/Patterson
(KP1)
3.2
Lower Mill Creek
(ML1)
3.5
Unknown
Upper Mill Creek
(ML2)
3.5
Unknown
Lower
Shackleford/Mill
(SM1)
2.8
Unknown
Lower Shackleford
Creek (SH1)
2.0
Unknown
Middle Shackleford
Creek (SH2)
2.0
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Partial
Partial
Partial
Riparian vegetation is generally
limited to single rows of trees.
Grazing and levees limit access to
the floodplain and downcutting
exacerbates adverse effects on
riparian regeneration. Riparian
fencing is minimal.
Unknown
Riparian conditions become
progressively poorer in
downstream locations due to
grazing and unstable channels.
Riparian trees are generally
absent. Riparian plantings and
fencing have had beneficial
results on lower Kidder Creek.
Unknown
Unstable channel and fluctuating
water table limit riparian
vegetation to scattered trees and
shrubs. Riparian fencing has had
3
Unknown
Unknown
Unknown
Partial
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locally positive effects and most
of the stream is fenced.
Lower Moffett Creek
(MT1)
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7.4
Historic and current land uses
have contributed to degradation
of riparian vegetation. High
flows periodically create
extensive channel instability.
4
Unknown
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Figure 1. Scott River Mainstem Reaches.
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Figure 2. Scott River Tributary Reaches.
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4.0
Study Methods
4.1
Riparian Cover Mapping
The first step in the riparian vegetation assessment should be mapping the distribution of
riparian vegetation in the Scott River. Mapping should be done using the most current available
aerial photographs, alternative imagery, or low-level oblique aerial photography (NCRWQCB
2014), and standard vegetation mapping protocols. Digital color aerial imagery available from
the National Agriculture Imagery Project (2012) is recommended. Additional commercially
available imagery may be used to enhance the mapping. The level of resolution should
distinguish mapping units of 0.25 acre. Many of the mapping units will consist of linear polygons
with narrow vegetation cover. At the minimum, cover should be classified as herbaceous and/or
emergent aquatic vegetation, shrub, and tree dominated. If feasible, polygons should be
classified at the species level for later verification in the field. In addition to providing a
comprehensive picture of the riparian vegetation, the mapping will suggest locations where
connectivity can be increased through targeted restoration actions (Harris and Olson 1997;
Olson and Harris 1997). Examples of mapping at the life form and plant community levels in the
Scott River watershed are shown in Appendix B.
Aerial photograph interpretation will yield at least the following general stratification in the study
areas:

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
Riparian vegetation absent
Riparian vegetation consists of herbaceous vegetation, including emergent aquatic
vegetation
Riparian vegetation consists of linear strips of trees or shrubs essentially one or few
canopies wide
Riparian vegetation consists of patches several canopies wide
These data in turn can be used to derive information on the following variables (Gonzalez del
Tanago and Garcia de Jalon 2006):
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

Longitudinal continuity (length of riparian vegetation patches)
Width of riparian vegetation patches
Lifeform (herbaceous, emergent aquatic, shrub and tree dominated)
As illustrated in Appendix B, it is expected that the structure and composition of much of the
riparian vegetation can be determined from the mapping. Aerial imagery mapping will also
identify locations where bank and floodplain conditions have been degraded by past land uses
or natural events. Historic river photographs held at the Siskiyou County library should be
reviewed as part of the assessment of channel and vegetation change over time. The Scott
River Strategic Action Plan (SRCD 2005) also contains much potentially useful information.
4.2
Field Sampling Plan
The majority of the study areas are on private land and access to sampling sites will be a
limiting factor. This constraint alone indicates how important a high quality aerial imagery
mapping will be for documenting the area and general characteristics of riparian vegetation.
Conditions in areas that are not available for sampling may need to be inferred based on
conditions where sampling is permitted. In lieu of actual plot measurements, vegetation
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conditions will be qualitatively determined. Conditions at inaccessible sites may be estimated
from accessible viewing points (Olson and Harris 1997).
Field sampling will have three principal objectives:



Verify aerial imagery mapping results
Augment the results of aerial imagery mapping by collecting data on riparian species
composition, width, offset, density, and canopy height.
Collect data that cannot be obtained from aerial imagery such as presence or absence
of natural regeneration, connectivity between the stream(s) and their floodplains and soil
conditions insofar as they affect the potential for riparian vegetation.
On the basis of the mapping from aerial imagery, choices can be made about where to focus
the necessarily limited sampling effort. Relatively greater sampling effort may be assigned to
locations with existing riparian vegetation where the cover is limited to ascertain environmental
or land use constraints on riparian expression. Constraints on sites with no existing riparian
vegetation may be determined by qualitative observations obtained through aerial photograph
interpretation supplemented by field studies.
4.3
Data Analysis
Data on the areal extent, composition and structure of riparian vegetation, and hydrologic and
ecological function variables should be summarized by stream reach and for each study area as
a whole. Aerial imagery mapping and field sampling will yield observations on environmental
and land use constraints. These may include agricultural encroachment, channel or bank
instability, channel incision, lack of access to water, unfavorable soil conditions or other factors.
Mechanisms of constraint should be recorded to the degree possible. Analysis should include
comparisons with previous characterizations of riparian vegetation (e.g. Kennedy et al. 2005)
where feasible.
Restoration and enhancement opportunities may exist at the stream reach and site scales. At
the stream reach scale, increasing connectivity of the riparian cover by filling in gaps in the
corridor can achieve several benefits including improvements in wildlife habitat and stream
shading and bank stabilization. At the site scale, the ecological functions of existing riparian
vegetation patches can be enhanced by encouraging changes in composition and structure e.g.,
introducing conifers or hardwood species that will eventually improve woody debris recruitment
and/or stream shade, eradicating exotic species, etc. There are several environmental and land
use conditions that will influence the feasibility of restoration at either scale. These include:
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Land use, particularly presence of grazing animals or cultivated fields. As of 2009, the
riparian zone along much of the Scott River main stem and some tributaries had been
fenced. Any efforts at restoration or enhancement must either control the potentially
negative impacts of agriculture or be focused on locations where agriculture is not
occurring.
Landowner willingness to engage in restoration and enhancement. The local Resource
Conservation District has successfully recruited landowners in the watershed to
participate in riparian protection and enhancement projects. Landowner willingness
does not always correlate with sites where restoration and enhancement would achieve
the greatest benefits.
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
Existing environmental conditions including access to water, soil type and landform.
Studies of riparian restoration potential commonly evaluate associations between
riparian communities, fluvial landforms, substrate and streamflow to determine potential
restoration reference conditions (Harris and Olson 1997; Harris 1999). This can be
inferred for portions of study reaches where features such as point bars and terraces
exist and there are remnant patches of relatively intact riparian communities.
There have been limited evaluations of riparian restoration and enhancement projects in the two
watersheds (Jopson 1995). Anecdotal information indicates that efforts to establish woody
riparian plants have been largely unsuccessful. Exclusion of grazing animals has benefited both
riparian and aquatic vegetation.
5.0
Deliverables
The results of this study should be a quantification of existing riparian habitat structure variables
(as defined above) within the Scott River study reaches, an estimate of the area of defined plant
community types, and a qualitative assessment of hydrologic and ecological function variables
of the riparian habitat (as defined above). Both digitized maps and reports should be produced
from this study.
6.0
Literature Cited
California Department of Fish and Game (CDFG). 2003. Shasta and Scott River Pilot for Coho
Salmon Recovery: with recommendations relating to Agriculture and Agricultural Water
Use. Prepared by The Shasta-Scott Coho Recovery Team. 125 pp.
California Department of Fish and Game (CDFG). 2004. Recovery Strategy for California Coho
Salmon. Report to the California Fish and Game Commission, Species Recovery Strategy
2004-1. California Department of Fish and Game, Native Anadromous Fish and Watershed
Branch. Sacramento, CA.
California Department of Fish and Game (CDFG). 2009. Scott River Watershed-Wide
Permitting Program. Final Environmental Impact Report. FEIR Volume I: Revisions to the
Draft EIR Text. 632 pp.
Foglia, L., A. McNally, and T. Harter. 2013a. Coupling a spatio-temporally distributed soil water
budget with stream-depletion functions to inform stakeholder-driven management of
groundwater-dependent ecosystems. Water Resources Research 49(11):7292-7310,
(doi:10.1002/wrcr.20555).
Foglia, L., A. McNally, C. Hall, L. Ledesma, R. Hines, and T. Harter. 2013b. Scott Valley
Integrated Hydrologic Model: Data Collection, Analysis, and Water Budget, Final Report.
Prepared by University of California Davis for North Coast Regional Water Board, dated
April 22, 2013. 101 pp.
González del Tánago, M., and D. Garcia de Jalon. 2006. Attributes for assessing the
environmental quality of riparian zones. Limnetica, 25(1-2): 389-402
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Harris, R.R., and Olson, C. 1997. Two-stage system for prioritizing riparian restoration at the
stream reach and community scales. Restoration Ecology 5(4S):34-42.
Harris, R.R. 1999. Defining reference conditions for restoration of riparian plant communities:
examples from California, USA. Environmental Management 24:55-63.
Harris, R.R., S.D. Kocher, J.M. Gerstein and C. Olson. 2005. Monitoring the Effectiveness of
Riparian Vegetation Restoration. University of California, Center for Forestry, Berkeley,
CA. 33 pp.
Harter, T., and R. Hines. 2008. Scott Valley community groundwater study plan. Report
prepared by Groundwater Cooperative Extension Program, University of California, Davis
for North Coast Regional Water Quality Control Board, Siskiyou County Resource
Conservation District, and Siskiyou County Board of Supervisors, dated February 11, 2008.
93 pp.
Jopson, T.M. 1995. Scott River Riparian Woodland Revegetation Demonstration Project: Final
Report FY 1994. Report prepared for Siskiyou Resource Conservation District. 19 pp.
Jopson, T.M. 1996. Scott River Riparian Woodland Revegetation Projects. Final Report FY
1995. Prepared for the Siskiyou Resource Conservation District. 20 pp.
Kennedy, J.A., F.M. Shilling, and J.H. Viers. 2005. Current and Potential Riparian Forest
Conditions Along Scott River Watershed Tributaries. Report prepared by University of
California, Davis for the North Coast Regional Water Quality Control Board. 50 pp.
Lewis, A.G. 1992. Scott River Riparian Zone Inventory and Evaluation. Report Prepared for
the Siskiyou Resource Conservation District. 132 pp.
Mack, S. 1958. Geology and groundwater features of Scott Valley, Siskiyou County, California.
U.S. Geological Survey Water Supply Paper No.1462. Washington, D.C., U. S. Govt.
Printing Office. 115 pp.
National Marine Fisheries Service (NMFS). 2012. Recovery Plan for the Southern Oregon
Northern California Coast Evolutionary Significant Unit of Coho Salmon (Oncorhynchus
kisutch). Volume II, Chapter 36, Scott River Population.
Normandeau Associates. 2013. Scott River and Shasta River study reaches. 1 October 2013
final report submitted to California Department of Fish and Wildlife, Yreka, CA. 30 pp.
North Coast Regional Water Quality Control Board (NCRWQCB). 2005. Staff Report for the
Action Plan for the Scott River Watershed Sediment and Temperature Total Maximum Daily
Loads. Available online at:
http://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/scott_river/staff_re
port.shtml
North Coast Regional Water Quality Control Board (NCRWQCB). 2011. Scott River Watershed
Water Quality Compliance and Trend Monitoring Plan. Prepared by NCRWB Staff. 37 pp.
North Coast Regional Water Quality Control Board (NCRWQCB). 2014. Bryan McFadin,
Senior Water Resource Control Engineer. Personal communication, September 2014.
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Olson, C. and Harris, R.R. 1997. Applying a two-stage system to prioritize riparian restoration
at the San Luis Rey River, San Diego County, California. Restoration Ecology 5(4S):43-55.
Scott River Watershed Council (SRWC). 2006. Initial Phase of the Scott River Watershed
Council Strategic Action Plan. October 2005 Update. 5/2/2006. 249 pp.
Siskiyou Resource Conservation District. 2001. Scott River Riparian Restoration Project.
Funded by USFWS Jobs in The Woods Contract #14-48-11333-J175. 17 pp.
Siskiyou Resource Conservation District. 2005. Initial Phase of the Scott River Watershed
Council Strategic Action Plan, October 2005 Update. Report prepared by the Fiscal
Administrator, Siskiyou Resource Conservation District, Etna, CA. 258 pp.
Watershed Sciences. 2004. Aerial surveys using thermal infrared and color videography: Scott
River and Shasta River sub-basins. Final report by Watershed Sciences, Inc., Corvallis,
OR, submitted to the California North Coast Regional Water Quality Control Board and
University of California Davis, dated February 26, 2004. 59 pp.
Watershed Sciences. 2007. Airborne thermal infrared remote sensing, Scott River Basin, CA.
Prepared by Watershed Sciences, Inc., Corvallis, OR, submitted to Quartz Valley Indian
Reservation, Ft. Jones, CA, revised report dated June 1, 2007. 31 pp.
Watershed Sciences. 2010. LiDAR Remote Sensing Data: Scott Valley Study Area, Oregon
[sic]. Report prepared by Watershed Sciences, Inc., Corvallis, OR, submitted to TetraTech,
Lafayette, CA, dated November 11, 2010. 24 pp.
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Appendix A
Representative Riparian Conditions on the Scott River
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In many locations the riparian vegetation consists of a one-canopy wide gallery.
In other locations, the riparian vegetation is entirely absent or limited to a few relict trees.
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Tailings are generally devoid of riparian vegetation.
Point bars may have residual patches or stringers of riparian vegetation. Some relatively intact
patches still exist on the river.
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The upper reaches of the Scott River and the East Fork (depicted here) have riparian galleries
bordered by forest vegetation types.
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Appendix B
Examples of Vegetation Delineation from Aerial Photography
in a Test Reach of the Scott River Basin
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A
Vegetation delineations along a ~1/3 mile stretch of the Scott River (~65 acres)
A
Same stretch of the Scott River, along with vegetation type assignments and stature cover
estimates.
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A
Enlargement of Area A above, showing vegetation delineations.
A
Enlargement of Area A above, showing vegetation delineations and attributes, including height
categories.
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