The blue green algae has dissipated at Blackmans Lake. Please be cautious and avoid areas of blooms that look like green or blue surface scums or algae clumps.
The Blackmans Lake Cyanobacteria Management Plan (CMP) has been completed by Herrera Environmental Consultants, Inc. (Herrera), and was adopted by the City Council on August 20, 2024. Based on the recommended alternatives from the CMP, a phosphorus sediment inactivation method will be implemented at Blackmans Lake to address the blue green algae. Alum treatment is a phosphorus sediment inactivation method that has been used successfully at Snohomish County lakes to reduce the occurrence of blue green algae blooms.
Herrera will develop a plan to implement the alum treatment and assist the City with the permit, treatment and monitoring process. The alum treatment is tentatively scheduled for spring 2025. The treatment schedule will be dependent on weather, and the availability of the contractor and materials.