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Columbia River Flows
![](3D"slide0042_image003.jpg")
Chris
Hathaway
Presentation
to the
Vancouver
Lake Watershed Partnership
April
20, 2005
Columbia River Background
•2=
59,000
square mile watershed
•D=
rains
portions of 7 states, 2 provinces
•1=
200
miles long
•A=
verage
discharge 275,000 cfs
•P=
rimarily
snowmelt driven system
•S=
econd
to Missouri-Mississippi in volume
•M=
ajor
tributaries include:
–K=
ootenai,
Flathead/Pend Oreille, Snake River, and Willamette River
Lower Columbia River
&#=
8226;Bonneville
Dam to the Pacific Ocean
&#=
8226;146
river miles
=
226;Watershed
of approximately 18,000 square miles
&#=
8226;Major
tributaries include:
–Sandy,
Washougal, Willamette, Lewis, Kalama, Cowlitz
Geography
•River emerges from a s=
teep
walled Gorge below Washougal
•Stretch from Washougal=
to
Longview
–Broad floodplain
<=
/span>
–Elongated islands (Ree=
d,
Government, Hayden, Sauvie, Bachelor)
–Sloughs, side channels,
etc.
–Last remnants of huge
swamp riparian system formerly nourished by annual
flooding
–<=
/span>
Riparian Swamp System
<=
span
style=3D'font-size:88%'>•Sandy River Delta
<=
span
style=3D'font-size:88%'>•Smith and Bybee Lake
<=
span
style=3D'font-size:88%'>•Vancouver Lake
<=
span
style=3D'font-size:88%'>•Sauvie Island
<=
span
style=3D'font-size:88%'>•Ridgefield Wildlife Refuge
<=
span
style=3D'font-size:88%;visibility:hidden'>•
•Each an example of the type of floodplains =
=
habitats and wetlands once abundant in the =
lower Columbia River. Vancouver Lake
•Formerly connected to
Columbia River via Mullligan Slough and Lake River
<=
span
class=3DBB style=3D'position:absolute;left:-4.43%'>•Complex
floodplain habitat
•Network of
sloughs, wetlands, and channels that likely moved around wi=
th some
frequency in response to annual flooding. A Changed River
<=
span
class=3DBB style=3D'position:absolute;left:-4.43%'>•Developme=
nt
<=
span
class=3DBB style=3D'position:absolute;left:-4.43%'>•Diking and
draining
<=
span
class=3DBB style=3D'position:absolute;left:-4.43%'>•Agricultu=
re
<=
span
class=3DBB style=3D'position:absolute;left:-4.43%'>•Dredging&=
#13;
<=
span
class=3DBB style=3D'position:absolute;left:-4.43%'>•Dam build=
ing and
flow regulation
<=
span
style=3D'visibility:hidden'>•
<=
span
style=3D'visibility:hidden'>•
Hydrologic Conditions
=
226;Columbia
River flows (and habitats) have been impacted by:
&=
#8211;Dam
Construction and Operation
&=
#8211;Irrigation
Withdrawals
&=
#8211;Shoreline
Anchoring
&=
#8211;Channel
Dredging
&=
#8211;Channelization
![](3D"slide0009_image005.jpg")
Flow Regulation
•29 Major federal dams in Columbia River basin
•Dozens of non-federal
dams
•<=
/span>Hundreds of smaller =
dams
•One of the worlds’ =
largest hydroelectric =
systems
•
•