Forwarded by Jane Clark

CLEAR LAKE STUDY NEARING COMPLETION

CLEAR LAKE - The water sampling portion of the diagnostic study of Clear
Lake will be wrapping up at the end of September and then the analysis
begins.  John Downing, the Iowa State professor heading up the study for
the DNR, will use the data to identify ways to improve the overall water
quality for the lake.

Wind, boat traffic and carp and bullheads all stir up nutrients making
Clear Lake turbid and difficult for aquatic vegetation to grow.  Aquatic
vegetation is important for lakes because the plants stabilize the bottom,
use nutrients in the water and protect the shoreline.  Identifying the
sources of nutrients will also be part of the study and could include
runoff from urban areas, septic tank discharges and agriculture runoff.

"Wind velocity has a direct impact on turbidity," he said.  "Carp and
bullheads will continue to stir up nutrients in the lake.  We will have to
identify ways to deal with these problems."

Downing said changes could include landscape modifications, expanding the
park land, dredging the west end of the lake, known locally as "Little
Lake," and modifications in the watershed.

The Iowa State group identified Ventura Marsh as one point where sediment
and nutrients enter Clear Lake.  The shallow marsh was home to carp and
bullheads that were stirring up sediment and nutrients, which would then
spill over into Clear Lake.  In June the DNR drew down the marsh water
level and sprayed rotenone in the water to kill the fish.  The results have
been amazing.

"The water cleared up so radically that it couldn't be measured with a
secchi disk because the disk was always on the bottom," Downing said.  "The
difference in water clarity is just amazing."

The final report will be done around the end of June 2001 and the solutions
will probably be expensive.  Just to remove one meter of silt from the
Little Lake area would cost in the neighborhood of $6 million, Downing
said, and then you have to find a place to put the spoil.

After all the work is completed, and solutions are identified and put into
place, Downing said people should not expect the lake to be cleaned up
overnight.

"If we do everything right, we are looking at a 10 to 30 year recovery
period for the lake," he said.

For more information, contact Don Bonneau at 515-281-8663.

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