Water Quality Improvement Project
© Tiffany Collier Withrow, Flickr.
Excessive nutrient inputs to lakes provide aquatic plant and algae dominance, making lakes unsuitable for recreation or viewing enjoyment. Phosphorus is one of the nutrients. When it is discharged into a water body, like a lake, it fuels the growth of algae.
Excessive algae growth reduces water clarity, increases oxygen demand in the bottom sediments severely impacting coldwater aquatic habitat, and can, depending on the dominant algae present, pose a human health risk.
Ecology developed a total maximum daily load (TMDL) study and submitted it to the Environmental Protection Agency (EPA). EPA approved the TMDL in April 1993.
The primary purpose for restoring water quality in Wapato Lake was to meet water quality standards for recreational uses while enabling its continued use as a winter stormwater detention facility. Implementation measures included applying alum treatments to precipitate/inactivate phosphorus in the water; divert stormwater to a wetland; dilute/flush lake water; drawdown water levels in the lake; apply stormwater controls; and educate the public about phosphorus issues. Of the measures used, the ones that produced the most significant results were stormwater diversion to a wetland; and alum treatments.
Wapato Lake Total Phosphorus Total Maximum Daily Load (Ecology publication)
Lake restoration and management for algae
WRIA 12: Chambers-Clover Watershed Information (Water web site)
# of TMDLs: 1
TMDL approved by EPA
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