Base Geography
About the CLackamas River Watershed
Figure 2
The watershed drains more than 940 square miles, or 600, 700 acres. For more than halfits length,
CLackamas River elevation and key places
the Clackamas River flows through forested areas over rugged terrain. The lower reaches flow through
agricultural areas and then densely developed areas.
Collawash River (57.0)
6000
Oak Grove Fork (53.0)
Roaring River (44.0)
Fish Creek (41 .7)
The Clackamas begins on the slopes of 0/a/lie Butte, a High Cascade volcano. The river flows 82.7
miles from its headwaters (elevation 6,000 feet) to its confluence with the Wil/amette River near
Gladstone and Oregon City (elevation I 2 feet). The river elevation profile shown in Figure 2 was created
South Fork of the Clackamas River (34.6)
4000
using a GIS and spreadsheet software. More than 3, 700 points along the Clackamas River (approxi-
North Fork Dam (31.1)
Faraday Dam (26.2)
mately every I 00 feet) were assigned an elevation. The resulting sequence ofpoints was then loaded
River Mill Dam (23.3)
into spreadsheet software and plotted.
2000
Eagle Creek (16.7)
Deep Creek (12.1)
Base MapO
Clear Creek (8.0)
The road data for federal lands in the upper water-
This base map shows an oulHne ofthe Clackamas
shed are more detailed than in the privately owned
River watershed along with rivers, streams, roads and
portions ofthe lower watershed. This occurs be-
subwatershed boundaries.
cause federal agencies have done more extensive
0
80
60
40
20
0
River Mile (from mouth of river)
mapping and field-checking of roads (including gravel
Figure 3
Rivers and streams: Five sources supphed river and
roads) on their lands than anyone has done on
stream information for different parts ofthe waterprivate land. The U.S. Census Bureau's road file,
Road density
shed, as shown on this base map: the U.S. Forest
which covers privately owned lands, contains some
Service (USFS), U.S. Bureau of Land Management
(but not all) private roads.
(BLM), U.S. Geoogica Survey (USGS), Cackamas
County assessor and a GIS flow accumulation modeL
Figure 3 shows road density, or miles of roads per
S u bwate rshed
Upper Clackamas River
3.2
square mile of land, for each subwatershed. Both
Hot Springs Fork Collawash River
3.0
An Arc/nfo program caHed the flow accumulation
paved roads and gravel USFS roads are included.
Collawash River
2.3
model was used to locate probable" streams in
Note that the Lower Clackamas subwatershed
Oak Grove Fork Clackamas River
3.3
areas where the existing stream network lacked
( mostly urban) has 5.6 road miles per square mile,
Fish Creek
3.4
detail. Using a digital model ofthe terrain, the
while the Roaring River subwatershed (mostly
Roaring River
07
program calculates the direction ofwater flow from
forested) has only 0.7 road miles per square mile.
South Fork Clackamas River
3.4
each point in the watershed, based on the elevations
Other subwatersheds in the Mt. Hood National
surrounding that point. The streams and streambeds
Forest (such as Fish Creek, with 3.4 miles ofroad per
Middle Clackamas River
3.3
North Fork Clackamas River
3.1
resulting from this process were used to supplement
square mile) show comparable road density with
existing stream information.
that in urban watersheds, likely because of the
Note: On severa/ maps /n th/s at/as we have used
extensive road data kept by the USFS.
Eagle Creek
3.1
Goose Creek
4.2
Deep Creek
3.6
Richardson Creek
stream and river informatian provided by the Oregon
Note: Road density data were produced in I 988- 1 996
Department ofFish and Wildlife. This information shows
5.0
Clear Creek
3.9
and may not reflect current conditions. For example,
only major streams and rivers and was used in situa-
Rock Creek
4.7
because the LISPS road data were produced in / 994,
Lower Clackamas River
tions where showing all streams would have c/uttered
5.6
they do not reflect /ogging roads that have since been
the map.
0.0
1.0
2.0
3.0
4.0
abandoned or removed. New roads built since I 996 in
Roads: Four sources provided information about
roads in the watershed: the USFS, BLM, USGS and
U.S. Census Bureau.
urban areas are a/so not inc/uded.
Miles of road per square mile of land
5.0
6.0
Subwatersheds: Sixteen subwaiiersheds are shown
on the map. The USFS provided boundaries for
USFS. In contrast, most ofthe lower watershed is
the upper eight subwatersheds; Metro provided
privately owned. The area in between the national
five; and both agencies delineated portions of three
forest and the lower watershed includes parcels of
subwatersheds. The watershed boundaries are non-
land owned by private timber companies and the
standardized breakdowns and were delineated at the
TabLe 3
Hierarchical classification for the Clackamas subbasin
Hierarchy name
Code
Region
Subregion
Accounting unit (basin)
17
09
00
Cataloging unit (subbasin)
U.S. Bureau of Land Management.
discretion ofthe originating agency.
Because watersheds are hierarchical (nested within each other),the system for numbering them is also hierarchical.As shown inTable 3, each level ofthe hierarchy is
Also shown on the map are private land holdings
Note: /n the past, each agency has delineated bound-
II
I
in the Mt. Hood National Forest and managed by the
within the Mt. Hood National Forest, including the BP
ar/es for river basins, subbasins, watersheds and
John Industrial Forest (North Fork Clackamas), PGE
subwaters/ieds to meet their purposes, meaning that
property (North Fork Clackamas) and Austin Hot
one agency might divide the C/ackamas River watershed
Springs (Upper Clackamas).
assigned a two-digit number beginning with the largest unit, region.The hydrologic unit code (HUC) for the Clackamas watershed is I 70900 I
I
.
Note: Although some
agencies call the land draining to the Clackamas River a "subbasin," we call it a "watershed" for this project.
into seven subwatersheds, while another agency might
separate it into I 2 subwatersheds.
The county parks that appear on the map are Barton
( east of Carver), Eagle Fern (northeast of Estacada)
The Natural Resources Conservation Service
Table 4
Figure 4
Ownership in the Clackamas River watershed
Ownership in the
and Metzler (southwest of Estacada). The state also
(NRCS, formerly the Soil Conservation Service) and
owns several small parcels in the watershed, the
the U.S. Geological Survey are currently developing a
largest ofwhich is Mclver Park, west of Estacada.
Owner
USFS
Ctackamas River watershed
Acres
Pc rce nt
413,850
68,89
I 2,786
2. I 3
I 708
0.28
16,827
2.80
I 20,986
20.14
standard set ofwatershed boundaries that can be
applied throughout the United States. These new
boundaries may be different than those shown on
this map. Eventually each small watershed within the
Clackamas will be assigned a standard "hydrologic
unit code" (seeTable 3) so that data gathered by one
agency can be referenced by another for the same
area. At the time ofthis printing, these boundaries
Ownership information shown on the map is based
BLM
on a combination ofthe Clackamas County tax
assessor data base, State Service Center for GIS
Other Federal
statewide ownership data and private forest land
data from the BLM. It represents ownership at the
time the data were collected and will change as
Tribal
F
Private
G
property is bought and sold.
PrivateTimber
30,597
5.09
3,987
0.66
had not yet been delineated or standardized.
Other Public
ELevation 0
Property Ownership )
Land ownership information forthe Clackamas River
watershed is included early in the atlas because
ownership patterns greatly affected how we gathered
and displayed information about the watershed.
This map shows elevations in the watershed based
on data from a digital elevation model with shaded
Ecoregions
relief A digital elevation model, or DEM, is a grid-
on several levels, from broad expanses of land (Level
geologic classifications shown on this map, contact
ecoregions) to more specific, smaller ecoregions
the Oregon Department of Geology and Mineral
I
Ecoregions are large areas that have a similar type,
based computer model ofthe terrain. DEMs are
quality and quantity ofenvironmental resources
(Level 4).
derived from contour lines, which are commonly
such as soils, topography and native vegetation. For
Note: The sca/e ofthis geology map, 1:500,000, is very
seen on USGS topographic maps. For the Clackamas
example, much ofthe upper watershed is classified as
As shown inTable 4 and Figure 4, more than 72
watershed, each grid cell covers I /4 acre.
25 percent is privately owned.
The Clackamas River watershed can roughly be
"Cascade Crest, Montane Forest," while parts of the
The Clackamas watershed DEM contains approxi-
central watershed are classified as Western Cas-
The general geologic units found in the watershed
an overview for the entire watershed. The USFS has
mately 2.5 million grid cells, each representing the
cades, Lowlands andValleys." Ecoregions can assist
are shown on this map, based on the I 99 I Walker!
gathered more detailed data about geology on its lands.
average elevation ofthat 114 acre. In this case, the
resource managers in seeing broad regional patterns.
McLeod geology map of Oregon from the USGS.
This information is avai/able in watershed analyses
Briefdescriptions ofthe geologic units - such as
specific to each subwatershed.
shaded reliefsimulation ofthe terrain shows shadows
The Level 4 ecoregion boundaries shown on this
divided in half with nearly all ofthe upper watershed
coarse, meaning that it cannot be used to determine
Geology
precise geo/ogic units in small areas, but does provide
percent ofthe land in the Clackamas River watershed is publicly owned, about 3 percent is tribal and
Industries orthe USGS.
cast by a light source from the northwest.
map were provided by the U.S. Environmental
sedimentary rocks, basalt, or glacial deposits - are
given in the map legend. To learn more about the
Protection Agency. Scientists designate ecoregions
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