Phosphorus mitigation demonstration project on Clear Lake starts April 13

By Lake County News Reports | Apr 10, 2026

LAKE COUNTY, Calif. — A special project meant to address the health of Clear Lake will begin next week.

Lake County is sponsoring a demonstration project led by EutroPHIX and approved by the Clear Lake Blue Ribbon Committee. 

Excess phosphorus is a key driver of harmful algal blooms in Clear Lake. This project will implement a phosphorus mitigation demonstration in the Upper Arm of Clear Lake.

From April 13 to 24, EutroPHIX will apply EutroSORB G, a safe and effective phosphorus-binding treatment, to lake sediments within a 400-acre treatment area located about 2 miles offshore. 

This project will not affect lake uses such as boating, fishing or drinking water. 

Officials said the project is an important step in building the foundation for future large-scale rehabilitation efforts in Clear Lake. 

By reducing the release of phosphorus from sediments into the water, the project is expected to mitigate up to 14,500 pounds of phosphorus over time. Reducing phosphorus helps limit harmful algal blooms and supports healthier, more usable water for the community.

Work will be based out of Lucerne Harbor Park from April 13 to 24. 

During that time, a portion of the parking lot and half of the boat launch will be reserved for project operations. Closed areas will be clearly marked, and the rest of the park and boat launch will remain open to the public, though parking will be limited until work is complete.

If the project finishes before April 24, all parking restrictions will be lifted early.

Multiple application boats will travel between Lucerne Harbor Park and the offshore treatment area several times each day. 

Members of the public are asked to give contractors space on the water as they carry out this work safely and efficiently.

For more information, please contact Lake County Water Resources at 707-263-2344 or water.resources@lakecountyca.gov.

A map of temporary closure areas at Lucerne Harbor Park during the demonstration project. Image courtesy of the county of Lake.