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Cal-WATCH

Participate in the Cal-WATCH Study

Testing drinking water from wells, intakes, and creeks

Over 60% of Lake County residents receive their drinking water from Clear Lake. For those not using a public water system for household water, testing for contaminants such as cyanotoxins from HABs, nitrates, coliform bacteria, and herbicides is not regularly done.

In this study, our goals are to:

  • Understand whether there are contaminants that may pose a health risk to those drawing water from untreated and untested lake intakes or wells
  • Understand whether similar contaminants may pose a health risk to those who live alongside and draw water from creeks in Lake County
  • Educate residents on potential health risks from untested drinking water
  • Offer a one-time test for contaminants of at-risk wells and lake water intakes

Interested in having your drinking water tested?

To see if you qualify, please complete a short online form by clicking on the link below. A researcher will follow up with you regardless of whether or not you are eligible to participate.

This year, our program reviewed several public data sources to identify homes that may be at various risk due to drinking water contamination. If your home meet one or more of the following criteria, you may be eligible to participate:

  • Within 2250 feet of an identified clean up site on https://geotracker.waterboards.ca.gov
  • Within 2250 feet of a septic tank
  • Within a square mile of elevated water quality risk: https://shorturl.at/YboS1
  • Within a square mile of elevated nitrate quality risk
  • Within a square mile of elevated agricultural pesticide use

Why is this important? What are you interested in testing?

  • Depending on the clean up site identified, we're interested in potential contaminants that may enter drinking water including gasoline-related compounds, arsenic, hexavalent chromium, 1,2,3-trichloropropane, uranium, and others that imapact health.
  • Poorly maintained septic systems can sometimes lead to bacteria in nearby domestic wells.
  • As part of state bill-200, an aquifer risk map was developed to prioritize areas where domestic wells and state small water systems might be accessing groundwater that doesn't meet primary drinking water standards.
  • Nitrates can be harmful to humans and should be avoided by infants and pregnant women.
  • Exposure to certain pesticides is linked to poor health. Health concerns associated with pesticides include neurodevelopmental outcomes, respiratory concerns, cancer, and other conditions.

Complete our screening form to see if you are eligible to participate


If you are a resident of a home with a well or intake, check out our Cal-WATCH Resources page.

Have you visited Clear Lake in the last week, month, or year? We'd like to know.

We are interested in hearing about what you know about Harmful Algal Blooms and whether or not you may have come in contact with them while visiting beaches/shorelines along Clear Lake or creeks in Lake County. Our survey was developed by state and local agencies and Lake County Tribes to better understand how people and pets encounter and avoid harmful algal blooms (HABs).

This survey is currently closed; however, please contact us if you'd like additional information.

Learn about potential well water contaminants and their impacts

Private wells can be contaminated by naturally occurring sources and human activities as seen in this diagram. To learn more about these potential contaminants and their impacts, click here.

Diagram of how water reaches wells

Source: EPA Potential Well Water Contaminants and their Impacts

There are also measures you can take to protect your health today. Find out if your water is safe to cook and drink. Note that boiling water will not remove algal toxins. When in doubt, use store bought water.

HABs and drinking water contaminants are difficult and expensive to eliminate, but exposures can be prevented through public education in impacted areas. There are measures you can take to protect your health:


If you suspect a bloom or would like to file a report, please call 1-844-729-6466, email CyanoHAB.Reports@waterboards.ca.gov, or submit a form at https://mywaterquality.ca.gov/habs/do/bloomreport.html.


Additional information on HABs, cyanotoxins, blue-green algae:
Big Valley Band of Pomo Indians Clear Lake Cyanotoxins
Cyanobacteria in Lake County
Freshwater CyanoHABs Program (State Water Resources Control Board)
Office of Environmental Health Hazard Assessment Harmful Algal Blooms
Tracking California Harmful Algal Blooms

Learn more about the CalWATCH project

The Cal-WATCH project (1 NUE1EH001427-01-00) is supported by the Centers for Disease Control and Prevention of the U.S. Department of Health and Human Services (HHS) as part of a financial assistance award totaling $290,000 in year 1, with 100 percent funded by CDC/HHS. The contents are those of the author(s) and do not necessarily represent the official views of, nor an endorsement, by CDC/HHS, or the U.S. Government.