Purpose: Water samples from natural recreational waters of San Mateo County are sampled each week for concentrations of indicator bacteria.

If concentrations of indicator bacteria exceed State or County standards, the area is posted to warn users that they may become ill if they engage in water contact activities in the posted area. This map highlights locations that have elevated levels of indicator bacteria and are posted with warning signs. The map also presents all test results for all sites over the past 90 days.

Beaches are posted -- when single samples exceed 10,000 Total Coliform, 400 E. coli, or 104 Enterococci, -- or when a 5-week geometric mean exceeds 1,000 Total Coliform, 200 E. coli or 35 Enterococci.
Creeks are posted when single samples exceed 400 E. coli. The Environmental Health Division ensures a safe and healthful environment in the county's 20 cities and unincorporated areas through education, monitoring and enforcement of a variety of regulatory programs as well as ongoing services to the community.

For questions about this program or the data displayed in the viewer, contact: Environmental Health 2000 Alameda de las Pulgas, Suite 100 San Mateo, CA 94403 Phone: (650) 372-6200 Fax: (650) 627-8244, or visit: County San Mateo Environmental Health Website

For general inquires regarding County-wide GIS, email to: countygis@smcgov.org
455 County Center, 3rd Floor Redwood City, California, 94063 Phone: (650) 363-4108 Fax: (650) 363-7800

Geospatial Metadata: Full descriptions of all San Mateo County GIS data can be found in the County GIS Metadata Catalog .

Access and Use Constraints: Terms of Use for San Mateo County Data Website (rev. 10/12/2010)


By using data on this website, you agree to the following. If you do not agree to all listed terms, you are prohibited from using the data.

1. Legal Disclaimer: The data on the SMC Data website is provided “as-is,” and San Mateo County makes no representations or warranties of any kind with respect to such data. The data is subject to change and may be changed at any time without notice. The data may also contain inaccuracies, errors, or omissions, and you use this data with an assumption of all associated risks. In no event will San Mateo County be liable to you, or anyone using information, services, reports, etc. that you provide, for any damages whatsoever, whether direct, indirect, special or consequential relating to your use or inability to use the data, regardless of the legal theory for the claim. By using the data, you agree to notify all third-parties, who utilize services or information you provide that incorporate this data, of this disclaimer, and further you agree to defend and hold the County harmless for any damages of any kind which may be the result of use of the data being provided.

2. Public Information: All datasets accessed through the SMC Data website are confined to public information governed by California State Public Records law, Government Code ยง 6250 et. seq.

3. Privacy & Security: Information accessed through SMC Data is provided in compliance with agency policies and legal standards.

4. Citing Data: The County's preferred citation for each dataset is included in its metadata. Users should also cite the date that data were accessed or retrieved from SMC Data. Finally, users must clearly state that “SMC Data and San Mateo County cannot vouch for the data or analyses derived from these data.”

5. Ownership of Information and Data: San Mateo County reserves all title, ownership, or other intellectual property rights in any data to the extent that such rights lie with the County. Users of data retrieved from SMC Data agree not to assert any title, ownership, or other intellectual property rights in any data to the extent such rights already reside with the County.


6. Governing Law, Assignment and Termination:

These terms shall be governed by and interpreted under the laws of the State of California, and any legal action related to these terms shall be venued in San Mateo County, California.

Any transfer or assignment of data by the user is itself done subject to these terms. To the extent these terms are modified or terminated, use of data previously obtained under these terms shall be governed by the terms under which the data was obtained.