Anderson Lake, in Jefferson County, has annual cyanobacteria blooms dominated by Dolichospermum (Anabaena), Aphanizomenon and Microcystis. The lake is a major producer of anatoxin-a, a potent neurotoxin. It is also located in a State Park and is popular for recreational activities. Under a grant from the Department of Ecology, Jefferson County Public Health completed a nutrient budget for the lake and watershed, and examine hydrologic conditions to help determine future management options for algae control in Anderson Lake.

Water Quality Report

The Anderson Lake Water Quality Report summarizes the results of one year of lake monitoring. It describes the hydrologic dynamics of Anderson Lake and the cycling of nutrients. A phosphorus budget is presented, which shows that internal loading from sediments is the primary source of eutrophication. Phosphorus was found to be the nutrient that contributes the most to the rapid growth of algae in the lake.

Next Steps

Washington State Parks has designated Anderson Lake as a natural system and, as such, it receives protection from human disturbance. Parks has been informed about the results of this study, and will take some time to consider its implications for management goals.