Where to check a California algae advisory
No single page covers every lake. These are the pages people use to check a California algae advisory, what each one covers and what it does not. Check more than one, and read the signs posted at the water.
This page is a dated snapshot. We read each page below on Oct 23, 2026, and pages change, move and go out of date without notice. Open the link to see what it says now. Lake Notice is independent and no agency or organization listed here has reviewed or approved this page.
Sources
| Source | Read on | What it covers | What it does not cover |
|---|---|---|---|
|
Water Boards: freshwater harmful algal bloom (FHAB) program page The web map the program page points to |
The state program behind the advisory records. The page lists recent advisories and notifications (for 2026 it named nine events, the latest dated Oct 2), a report form, a web map and the full data file. | The page read had no page for each water, no alerts and no dog guidance. The web map's site allows only Google's crawler in its robots.txt, so we did not read the map and say nothing here about what it shows. | |
| Water Boards advisory records on data.ca.gov | The state's advisory records as one data file, listed as public domain with no restrictions on public use and shown as last updated Oct 23, 2026. This is the file Lake Notice republishes. | A data file, not a lookup page for one lake. Reports are voluntary and many waters are never tested, so a water missing from the file is not a finding about the water. | |
| Sacramento County environmental health: recreational health program | Recreational health program pages that list pools and lake inspections. | We found no algae advisory content on the page read, and did not crawl the rest of the site. | |
| San Bernardino County Environmental Health: recreation and aquatic facilities | Recreational health program pages that list pools and lake inspections. | We found no algae advisory page on the pages read, and did not crawl the rest of the site. | |
|
East Bay Regional Park District: water quality The district's blue-green algae page |
A table of alert levels for East Bay regional park swim areas (Danger, Caution, or No Advisory Posted), with a dog warning on the district's blue-green algae page. On Oct 23, 2026 it listed the Del Valle East swim beach at Caution and Lake Temescal at Danger. | Only the district's own parks, shown as one current table. The pages read showed no history, no page for each water and no alert sign-up. A table that lists a swim area and a state record that covers a whole lake can show different levels on one day. | |
| Big Valley Band of Pomo: Clear Lake cyanotoxin program | The tribe's own sampling at Clear Lake: its page says samples are taken every two weeks in summer, lists current monitoring results and historical cyanotoxin data, and says the program began in 2014 with the Elem Indian Colony. | Clear Lake only. These are toxin samples, a different kind of record from the state's advisory records, and we did not read the results themselves. | |
| Lake Elsinore and San Jacinto Watersheds Authority: lake conditions | Lake Elsinore. The page says lake conditions are available at Elsinore Valley MWD. | We could not read Elsinore Valley MWD's site on Oct 23, 2026, so we say nothing about what it shows. | |
| U.S. EPA: harmful algal bloom advisories | A national page. EPA says it compiles and displays recreational and drinking HAB occurrence and/or advisory data publicly reported by states, on a monthly basis. | The page read is a national summary updated monthly, with no page for each lake. | |
| Swim Guide: California beaches | Free water quality information for more than 10,000 beaches, lakes, rivers and swimming holes, with status icons and historical status. California affiliates include Los Angeles Waterkeeper and San Diego Coastkeeper. | The pages read describe bacteria as the main indicator of beach water quality and did not describe an algae advisory. Grey means data more than a year old. The California page is mostly coast. | |
| Lake Notice (this site) | The state's advisory records, one page for each water: the latest status, the date it was posted, whether the state recorded an end, each reported spot and every record on file since 2016. It adds nothing the state did not record. | Lake Notice is not the source of any record and takes no water samples. It reads the state's file about once a day, so it can trail the state by about a day. A water that is not listed has no advisory on file, which is not the same as being free of algae, because most waters are never tested. The website sends no alerts. It is independent and is not affiliated with or reviewed by any agency. |
Counties
The five counties with the most waters in Lake Notice's data on Oct 23, 2026 were San Diego (67), Riverside (40), Sacramento (39), San Bernardino (36) and Contra Costa (32). We list a county only where we read a page of its own. On Oct 23, 2026 we could not load the environmental health pages for San Diego, Riverside and Contra Costa, so this page says nothing about them.
Why two pages can show different levels
Sources cover different spots and different days. A water's headline on Lake Notice shows the highest level among its reported spots, so a page that covers only one swim area can show a lower level for the same lake. Each water page lists every spot and its latest status.
More
About the data and its limits · Dogs and algae · Find a lake by county