The signs warning of toxic algae blooms at Waughop Lake remain in place eight years after they were first posted. As any regular visitor to the 350-plus acre Fort Steilacoom Park knows, the 30-acre lake regularly experiences the blue-green toxic algae blooms when temperatures rise.
Using grant money from the state Department of Ecology, the City Council authorized a study of the lake including a year-long monitoring of the water to determine the source of the high phosphorus levels producing the algae blooms.
At one time city officials believed the problems were caused by a combination of stormwater runoff, animal waste and failing septic systems. That information was corrected last year when a lake management plan was unveiled.
Engineering consulting firm Brown and Caldwell and Jim Gawel, University of Washington Tacoma associate professor of environmental chemistry and engineering, studied the lake and developed the plan.
The results of their work showed the nutrient-rich lake bottom was the culprit of the toxic algae blooms. Waughop Lake is a kettle lake, which means water doesn’t circulate naturally. Instead it sits in the basin.
To correct the problem man-made interventions are necessary.
Now the City Council is poised to approve a multi-phase plan aimed at improving water quality in the lake and ultimately reducing phosphorus levels.
The council received a presentation at the Feb. 27 study session from the consultants hired to completed the lake management plan study.
The presentation included a recommendation for how to proceed with cleaning up the water.
The suggested first phase is to treat the lake with alum, a chemical regularly used to remove phosphorus from fresh water. The city of Seattle recently used this chemical in Green Lake to minimize its algae blooms.
According to the state Department of Ecology’s website, when added to water “alum forms a fluffy, aluminum hydroxide precipitate called a floc. As the floc settles, it removes phosphorus and particulates (including algae) from the water column.”
The floc forms a layer on the sediment at the bottom of the lake that acts as a barrier to the phosphorus, preventing it from being released into the water which halts the algae blooms.
The second phase of the recommended treatment plan before the City Council calls for the eventual dredging of the lake bottom. This option is more costly and would only be done if money is available.
Suggested funding sources include requesting money from the state Legislature, grants or the creation of special purpose districts like a local improvement district, lake management district or a flood control zone management district.
The decision on how to proceed rests with the City Council and is expected to be made at a March 6 regular meeting.