TMDL Projects - Clear Lake Nutrient TMDL

Information Regarding the Status of Load Allocations

Through 2019 and 2020, Central Valley Water Board requested additional information and issued Enforcement Orders to responsible parties named in the Clear Lake Nutrient TMDL. The information provided from responsible parties was used to determine whether the parties are in compliance with the TMDL and summarized in the Technical Memorandum released in September 2021.


Irrigated Agriculture

Lake County

U.S. Bureau of Land Management (USBLM)

U.S. Forest Service (USFS)

Blue Ribbon Committee for the Rehabilitation of Clear Lake

The Blue Ribbon Committee for the Rehabilitation of Clear Lake, created by Assembly Bill 707 (Aguiar-Curry, Ch. 842, Statutes of 2017), was formed to make recommendations that will rehabilitate and restore Clear Lake. The Committee consists of 15 members, which includes representatives from tribes, UC Davis, the Central Valley Regional Water Quality Control Board, and members appointed by Lake County with expertise in agriculture, economics, environment and public water supplies. The Central Valley Regional Water Quality Control Board representative is Jennifer LaBay. The alternate representative from the Board is previous Board Member Robert Schneider.

More information regarding the Blue Ribbon Committee for the Rehabilitation of Clear Lake, along with Committee documents, is available on the Committee’s website.

Environmental Drivers Study in Clear Lake

The Southern California Coastal Water Research Project Authority (SCCWRPA) has been contracted by the State Water Resources Control Board and the Central Valley Regional Water Quality Control Board to lead a two-year study investigating environmental drivers contributing to cyanobacterial blooms and toxin production in Clear Lake, Lake County. The project will consist of developing and implementing a field study monitoring plan and identifying the specific triggers of cyanotoxin production. The results of this study will be used to develop recommended approaches to manage and mitigate cyanobacterial blooms in Clear Lake and identify next steps for the Clear Lake Nutrient TMDL.

Monitoring for the study has been delayed due to COVID-19 restrictions and is scheduled to begin in August 2020. Documents associated with the contract are available upon request. Please contact Taran Sahota via email at to request any copies of documents associated with the contract.

Clear Lake Watershed Activities and Resources

Clear Lake is the subject of many programs and activities that are vital to the health and safety of the watershed. The efforts in Clear Lake are not limited to the Clear Lake Nutrient TMDL Program, and the Tribal-led monitoring program, local and State agencies working on water quality issues, and studies conducted on the lake provide more insight into the condition and complexities of Clear Lake.

Clear Lake Cyanobacteria and Cyanotoxins Monitoring Program

  • The Big Valley Band of Pomo Indians and Elem Indian Colony began a Cyanobacteria and Cyanotoxin Monitoring Program in Clear Lake in 2014 to address the need for regular and active monitoring in the watershed. The program monitors over twenty sites across Clear Lake for toxins produced by cyanobacteria. To find more information regarding the program, the most recent cyanotoxin monitoring data for Clear Lake, and cyanobacteria impacts to Tribal water uses, please visit the Big Valley Band of Pomo Indians Program web page.

County of Lake Water Resources

  • The County of Lake Water Resources is responsible for the preservation, health, and growth of Clear Lake. For more information regarding cyanobacteria, recent harmful algal blooms (HABs), or to report a bloom, please visit the County of Lake Water Resources web page.

Clear Lake Drinking Water

Clear Lake Studies

  • Under the Blue Ribbon Committee for the Rehabilitation of Clear Lake researchers from UC Davis Center for Regional Change (CRC) and UC Davis Tahoe Environmental Research Center (TERC) are conducting research to guide the Blue Ribbon Committee in improving the environmental quality and economic outcomes for the communities surrounding Clear Lake in Lake County, California. The TERC study is collecting data to understand processes in the Clear Lake watershed that are negatively impacting the rehabilitation of lake water quality and ecosystem health. This data will inform local and State decision-making. Check the UC Davis Clear Lake and TERC Clear Lake Website for more information on the studies.

July 2018 Board Workshop

August 2017 Public Outreach

Available Documents

Subscribe to our Clear Lake Nutrient TMDL email list to receive notifications and the latest updates. After subscribing, you will need to check your email host for a confirmation email to complete the subscription.

Email Address: (required)
Your Full Name: (required)
(e.g. John Smith)

  Subscribe to our other email lists.

Contact Us