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Eastern
Washington University Develops Fisheries Management Plan
The Eastern Washington University
Fisheries Program is currently developing a fisheries management plan
for Rock Lake, Washington. Rock Lake, located in Whitman County, is
the largest natural lake east of the Columbia River in Washington
State. As part of the management plan, a baseline limnological survey
is being conducted to assess primary productivity and the water quality
for supporting warmwater and coldwater fishes. Holly Moffatt, an EWU
Masters program student in Biology, is conducting this survey for
her thesis.
Rock Lake is eight miles long, approximately a
half-mile wide, and has three basins of 150, 300 and 350 feet deep,
respectively. Sills of volcanic rock separate and isolate each basin.
Rock Creek plunges over two waterfalls before entering the lake at
the north end. Erosion of soils from farming practices enter Rock
Lake via Rock Creek and other intermittent tributaries that spill
over the canyon walls during the spring runoff. These sediments contribute
to the lake's high turbidity, which may affect the biological production
of the lake.
Using a YSI
6000UPG sonde, Moffatt is able to make
vertical water column profiles of temperature, turbidity, pH, conductivity,
and dissolved oxygen in each of the Lake's three basins. YSI's self-wiping
turbidity sensor makes it ideal for long-term deployments. The YSI
6000UPG is equipped with a depth sensor that can be lowered to 500
feet. Data that is collected and stored by the YSI sonde is downloaded
onto a PC for analysis using YSI's
EcoWatch for Windows.
Because of Rock Lake's unique morphometry, there
is the potential to have underwater springs present throughout the
lake. Subterranean fractures in the basalt allow aquifers to accumulate
water, which flows through joints emerging as underwater springs.
"The YSI 6000UPG gives us the ability to determine and analyze
the unique limnology of Rock Lake," says Moffatt. |
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