General%20Geology

1
Mill Creek/ Umpqua River Watershed
Prepared by Brenna Susee and Alyssa
Marquez G.I.S.
Physiography Cont Recent timber harvests in the
area have begun to occur, as also seen in Figure
six, as the little light green areas. The climate
is a Mediterranean climate with a wet winter and
a dry hot summer. The area is very wet and the
highest months for precipitation are November and
December averaging about 11 inches. Precipitation
annually ranges from high to low, low being 0.6in
and high being 12in. The precipitation can be
seen in figure 7.
INTRODUCTION The Mill Creek/ Umpqua river
watershed is located completely within Douglas
County and covers about 348,166,100 m2. Which is
in the southwestern region of Oregon.
Figure 5. DRGs
Figure 4. DEMs
Figure 1. Map of Oregon and Mill Creek/Umpqua
River Watershed
Figure 9. Soils
Figure 8. Geology (Bedrock)
Hydrologic Summary The Water shed lies in
three different Quads named, Deer Head Point,
Scottsburg, Devils Graveyard, Elk Peak, Loon
Lake, Old Blue, Golden Falls, Ivers Peak and
Kelley Butte. There are two major rivers that
feed the watershed the south and the north Umpqua
rivers. There are over 26 sites where streams
poor into or add to the Umpqua River.
Watershed Location The watershed is located in
Douglas county and flows from the Cascades until
it reaches the end of Douglas county. The Umpqua
river flows all the way to the ocean however the
end of the river is not included in this
watershed. It was formed through the North and
South Umpqua rivers that drain off the cascades.
This watershed and river flow through the coast
range. It is located South of the Willamette
Valley.
Figure 10. Streams on Precipitation
Figure 11. Streams
Conclusions The Mill Creek/ Umpqua Watershed is
mostly an area devoted to the Umpqua National
Forest and the rest is farmland or becoming a
place where clear cutting is very prevalent.
There are many streams fueling this watershed and
most of them are caused from run-off and snow
melt. The watershed in located completely in
Douglas, Co. and is a pretty large one as well.
Figure 6. Vegetation
Figure 7. precipitation
Figure 2. Watershed
Figure 3. Quads Watershed is located in.
General Geology The four types of bedrock
geology located in the watershed are OW, Tss, Tt,
and Ty, marine sedimentary rocks located more in
the northern part of the watershed near Elkton.
The soils were formed through a mix of
metamorphic, sedimentary and volcanic rock. Over
more than 150 soil types have been identified in
the region. The middle of the region is rich in
deep alluvial or heavy clay materials and other
areas are mixed alluvial, silt or clay structures.
Physiography The elevation of the watershed
changes from 360 ft above sea level to at sea
level, as shown in Figure 4, the digital
elevation model. As you can see in Figure 6 a
large area of the watersheds vegetation mostly
is comprised of Douglas Fir and Western Hemlock
Trees. Mixed conifer and broadleaf deciduous
forests cover the other large portion especially
in the southwestern part of the watershed.
References OregonGeology GIS Data Dr. Taylors
website Coast Watershed GIS Data Dr. Taylors
website Coast Streams GIS Data Dr. Taylors
website Precipitation GIS Data Dr. Taylors
website DEM GIS Data UO Libraries DRG GIS Data
UO Libraries Roads GIS Data ODOT Soil GIS Data
Soilmart