Clear Lake Water Quality

Welcome to the Water Resources & Watershed Protection District Water Quality Data Portal Pages!

This page will provide you with information regarding surface water monitoring for Clear Lake, Clear Lake tributaries, and selected other water bodies in Lake County. 

Why is monitoring Water Quality Important? 

Water Quality monitoring is important task for lake managers as the information collected can help inform best management decisions.   Monitoring water quality over time makes it possible for managers to notice trends, identify any changes within the lake or lake condition, and respond accordingly.  Trend monitoring also helps to identify when the lake water quality is improving or worsening based on some management action (like improving shoreline habitat, imposing lake-use restrictions etc.).  Because Clear Lake is a public trust asset, any water quality information collected from Clear Lake is freely available and open access – either through the links provided at this website, or by calling us at (707)263-2344 and we can help you find it! 

Here you can find links to all relevant portals and data for water quality collected within Lake County, for surface water programs. These data include those from Clear Lake, streams, and creeks and other water bodies such as Highland Springs, Blue Lakes, and Indian Valley. 

Browse the Project Descriptions below and explore the provided links to view, access, download, and use public water quality data collected by Water Resources staff and partners.  

Water Quality Programs, Description, Links 

Clear Lake Source Watershed Assessment Plan

A sanitary survey is a review of a public water system to assess their capability to supply safe drinking water. Primacy agencies are responsible for completing sanitary surveys. The 2023 Sanitary Survey is a collaborative document, created by Cal Rural Water Association and MC Engineering, with financial support from a NRCS National Water Quality Initiative Grant, Lake County Watershed Protection District and cost-share from all the private and public drinking water purveyors on Clear Lake. 

While this is a final document, we appreciate any feedback and review. You can submit any comments and questions to us at

Clear Lake Ambient Monitoring Program – Monthly WQ Monitoring

CLAMP (Clear Lake Ambient Monitoring Program) – This program collects monthly physical, chemical, and biological water quality data from the three arms of Clear Lake on a monthly basis.  This project is a continuation of the monthly Clear Lake sampling project that was supported by California Department of Water Resources since the 1960’s.

Available CLAMP Data is also on California Environmental Data Exchange Network (CEDEN).  Visit the CEDEN Query tool here:

Select “Programs” and search for and select “Clear Lake Ambient Monitoring Program” from the drop down list. At the bottom select the date range of the data you would like to see.

This project is described here:


Turning up the heat: Long-term water quality responses to wildfires & climate change in a hypereutrophic lake - De Palma-Dow 2022- Ecosphere-Wiley Online Library


Satellite Resources 

Bluewater Satellite Project Report - Funded by County of Lake (2011-2013) 


SFEI Harmful Algal Bloom Satellite Analysis Tool (10-day max aggregate satellite for cyanobacteria presence in California Water Bodies)

Harmful Algal Blooms Analysis Tool (

Bloom map Opens in new window

Current Research from United States Geological Survey for Clear Lake & Clear Lake Basin

Hydrological and Aquatic Ecology Studies at Clear Lake, California | U.S. Geological Survey (

Blue Ribbon Committee for the Rehabilitation of Clear Lake 

The 15-member Blue Ribbon Committee for the Rehabilitation of Clear Lake, created by Assembly Bill 707 

(Aguiar-Curry, Ch. 842, Statutes of 2017) includes representatives from tribes, Lake County, UC Davis and the Central Valley Regional Water Quality Control Board. It also includes four members appointed by Lake County with expertise in agriculture, economics, environment and public water supplies.

The Committee has been given the important charge of making recommendations for rehabilitating Clear Lake, which is critical to Lake County’s economy, ecosystem, and heritage. The expertise of these committee members will be invaluable to restoring this precious resource.

Creation of the committee is part of the State of California’ ongoing investments in Clear Lake, which include a $2 million multi-year scientific research contract with UC Davis, $5 million in voter-approved bonds from Proposition 68, and a recent $15 million bond-funded investment to aid in the Middle Creek Restoration project.

You can find more meeting information at the Blue Ribbon Committee Webpage here:

For data collected as part of Blue Ribbon Committee projects, those are below: 

UC Davis / Tahoe Environmental Research Center (TERC)

TERC Clear Lake Data Display:

Clear Lake Wind maps

USGS web site that provides access to online USGS data at Clear Lake including active gaging stations and water-quality data (in USGS NWIS system) for these and other sites in the area:

USGS data releases (in ScienceBase) for Clear Lake can be accessed here:

Links to journal articles and interpretive USGS reports are here:

And links to web pages for related projects are here:

Invasive Quagga Zebra Monitoring Program 

(QZ) Quagga-Zebra Mussel Monitoring Data Hub 

Literature & References

UN ANR Clear Lake Aquatic Website (CLAW) Water Quality Reports



We want to acknowledge and thank US EPA and Habematolel Pomo of Upper Lake for providing a National Environmental Information Exchange Network Grant (NEIEN) that provided funds for the development of this project and collection of WQ data.