Guide

Beach water: who samples what, and the beaches nobody does

Checked September 24, 2026 against Humboldt County Environmental Health, County of Mendocino Environmental Health and the State Water Resources Control Board; Sonoma and Marin added September 22, 2026 against Sonoma County Environmental Health and the County of Marin; San Luis Obispo, Santa Barbara and Ventura added September 24, 2026 against each county’s environmental health program; Los Angeles the same day against the county’s Public Health program and the City of Long Beach’s; Orange the same day against the County of Orange Health Care Agency; San Diego the same day against the county’s beach and bay program and the State Water Board file.

From Crescent City to Imperial Beach, each county decides whether its beaches are sampled, how often, and where the results go, and the answer runs from weekly results at dozens of sites to none at all. Each board below lists every beach on its stretch and says which ones anybody samples. On the north coast: Humboldt County samples five beaches, all in one twelve-mile stretch between the Mad River and Trinidad; the Mendocino coast has five sampled sites among its twenty-four beaches; and every beach in Del Norte County, Samoa, Centerville and the Lost Coast has no result at all.

On the Mendocino coast that is, north to south: Westport/Union Landing, Wages Creek and Chadbourne Gulch at Westport; Ten Mile River, MacKerricher State Park, Virgin Creek, Pudding Creek Beach and Glass Beach at Fort Bragg; Noyo River and Hare Creek at Noyo Harbor; Jug Handle State Reserve, Caspar Headlands State Beach, Russian Gulch State Park and Big River, Mendocino Bay at Mendocino; Van Damme State Park at Little River; Albion River and Navarro River Redwoods at Albion; Greenwood State Beach at Elk; Irish Beach, Manchester State Beach, Arena Cove and Schooner Bay at Point Arena; Anchor Bay and Gualala River at Gualala. Five of those — Pudding Creek Beach, Hare Creek, Caspar Headlands, Big River and Van Damme — are sampled every week and now carry a reading; see below. The rest are beaches the county’s programme names and nobody samples.

Who samples what

The State Water Resources Control Board keeps the list of who runs beach monitoring in California. Sixteen counties are on it. Humboldt is one. Del Norte is not on it at all — there is no beach water monitoring programme in the county, so Crescent City, Pebble Beach, Crescent Beach and Fort Dick have no results and never will until somebody funds one.

Humboldt County Environmental Health is paid for its programme by the U.S. EPA under the BEACH Act. It samples weekly, April through October, and not at all November through March. Outside those months the tile says the season is shut rather than “no warnings”, because those are different facts.

Mendocino County is on the Water Board’s list, and County of Mendocino Environmental Health does run a beach monitoring programme. The problem is where the results go. The county does not publish a current results table of its own, and its postings in California’s statewide Beach Water Quality Postings and Closures file are stale: that file was last updated in March 2026 and its newest Mendocino entry is from 2022. Its results are another matter. The county samples five coastal sites every week and files them with the State Water Board, whose Safe to Swim data is current, and the Mendocino coast board reads those five; the other nineteen beaches on that board are sampled by nobody. The details are under that board’s own heading below.

Humboldt’s five

Samples are taken at creek mouths, where stormwater runs into the sea — not out in the surf. That is where the bacteria arrive, so it is the strictest place to measure and the place to stay away from when a reading is bad.

Four of them have been sampled since the programme began in February 2003. The Mad River mouth site was added in November 2004.

Every beach on the north coast board

Del Norte and Humboldt, north to south, with the creek each sample is taken at, and whether anyone tests it.

Five monitored, seven not. The seven are the main public beach for each town group the sampling does not reach; there are many more beaches on the north coast than twelve, and none of those is monitored either.

Every beach on the Mendocino coast board

Twenty-four beaches, Westport to Gualala, north to south. The Monitored column asks whether a current result is published where anyone can read it. For five of them it is — see below; for the other nineteen nobody samples at all.

These are the county’s own sites, listed so that the tile can name them rather than go blank.

Where the five readings come from, and what was wrong before

This board said “nobody publishes a reading for this coast” for a day, and that was wrong. It was written after reading California’s Beach Water Quality Postings and Closures file, which was last updated in March 2026 and whose newest Mendocino row is from 2022. That is the POSTINGS file. The results are somewhere else and they are current: County of Mendocino Environmental Health samples five coastal sites every Monday and files them with the State Water Board, whose Safe to Swim dataset on data.ca.gov is updated daily. The newest Mendocino sample when this was written was September 8, 2026.

What the tile shows is a measurement, not a posting. The state sets a single-sample limit of 320 for E. coli and 110 for enterococcus, and a thirty-day average limit of 100 and 30 (CFU per 100 ml). A sample over one of those is a sample over a standard. Whether a beach is closed or posted is the county’s decision, and that decision is not in this file — ring the county.

Total and fecal coliform have no state limit at all. They are measured and printed here and never judged, because a tile that failed a beach on a coliform count would be inventing a number the state does not publish.

Every beach on the Sonoma and Marin board

This is the one stretch of California coast on this site where somebody samples the water and publishes the answer this week. Thirty-one sites, The Sea Ranch to the Marin Headlands, north to south — and two counties with two different habits. Sonoma County Environmental Health samples seven ocean beaches and posts a table with the counts on it; the County of Marin samples twenty-four sites, most of them on Tomales Bay and the creeks feeding it, and publishes them as a data feed with one word against each: OK, AVOID, or N/A.

Marin’s sites are mostly not surf. Tomales Bay, Papermill Creek, Drakes Estero and the ditches behind the beaches are where people wade, launch and swim on that coast, and they are also where the bacteria are: a ditch draining farmland after rain is a different animal from an open ocean beach, which is why the county samples the ditches at all.

Sonoma’s seven are the ocean beaches; the other thirty-one are Marin’s, seven of them on the bay side — China Camp and McNears for San Rafael, Paradise Beach for Tiburon, Schoonmaker and Horseshoe Cove’s three for Sausalito — which the county samples the same week as its ocean beaches. Three of Sonoma’s are signed differently on the county’s own results page from the way the parks are signed on the ground — Gualala Point Regional Park is “Gualala Regional Park Beach” there, Stillwater Cove is “Stillwater Regional Park Beach” — and the board matches on the county’s spelling, so a renamed row shows up as a broken test here rather than as a silent Check on somebody’s beach.

Every site on the San Mateo board

This is the best-covered coast on this site. San Mateo County Health samples weekly, on Monday mornings, year round, at 43 sites, and files every result to the same State Water Board dataset the Mendocino board reads. Twenty-six of the 43 are the ocean coast; the other five in that file are San Francisco Bay — Aquatic Park, Coyote Point, Kiteboard Beach, Lakeshore Park and Oyster Point Marina — and since September 24, 2026 they are on this board too, for its bay-side rows from South San Francisco to Redwood City.

The county’s posting hotline is (650) 599-1266. What the tile shows is a measurement against the state’s limit, not a posting: posting a beach is the county’s decision and is not in the file this reads.

Every site on the Santa Cruz board

Santa Cruz County Environmental Health samples twenty-five ocean sites and files the results to the same State Water Board dataset the Mendocino and San Mateo boards read. The thing to know about this county is that it does not sample them all at the same rate. The town beaches from Natural Bridges round to Rio del Mar — Cowell, Main, Lighthouse, Mitchell’s Cove, Natural Bridges, Capitola, New Brighton, Seacliff, Rio del Mar — are sampled every week, year round. Seabright and Twin Lakes about every two weeks. The rest — the north-county beaches at Davenport, the Live Oak pocket beaches, Pleasure Point, and the long beaches from Hidden Beach to the Pajaro — about once a month, less in winter. So a three-week-old reading at Manresa is current, and the tile says how often the county comes to each site rather than calling a monthly beach stale.

The county’s water quality laboratory is (831) 454-4624 and its Environmental Health office (831) 454-2022; its own advisories page lists the current postings. What the tile shows is a measurement against the state’s limit, not a posting: posting a beach is the county’s decision and is on that page, not in the file this reads.

Every site on the Monterey board

Monterey County Environmental Health samples thirteen sites that reach the same State Water Board dataset, and it samples all year: in the county’s own words, “monthly from November to April, then weekly between April 1 and October 31”. That sentence is true of the eight Peninsula beaches the county names on its own page — Del Monte and the Monterey Beach Hotel, San Carlos, Lovers Point, Asilomar, Spanish Bay, Stillwater Cove and Carmel Beach — which show thirty-odd sampling days a year in the file, San Carlos about every two weeks. The five state beaches — Moss Landing, Marina, Seaside, Carmel River and Julia Pfeiffer Burns — are in the same file at about once a month. Each row says which, and a monthly beach three weeks after its last sample is current, not stale. Nothing south of Julia Pfeiffer Burns is sampled: Lucia and Gorda have no beach on this list, and no sampled beach means no reading, not a clean one.

The county’s Beach Condition Hotline is (831) 755-4599, and it is the answer when this page and the county disagree: what the tile shows is a measurement against the state’s limit, not a posting. Posting a beach, or a rain advisory after a storm, is the county’s decision and is on the hotline, not in the file this reads.

Every site on the San Francisco board

San Francisco runs its own beach program — the Public Utilities Commission with the Department of Public Health — and in the city’s own words it samples “every week, year round”. Seventeen points are on the city’s map; fourteen of them reach the State Water Board dataset this site reads (Islais Creek, Crane Cove and Mission Creek do not), and the file agrees with the city: every one weekly, all year. Ocean Beach and Baker Beach are three points each and the bay beaches two or three, because the city keeps them apart and this page does too.

The city’s Recreational Beach Water Quality Hotline is (415) 242-2214, updated whenever new results come in, and it is the answer when this page and the city disagree: what the tile shows is a measurement against the state’s limit, not a posting. The city posts “No Swimming” signs when a sample fails the standard and whenever a combined-sewer discharge reaches a beach, and that posting is the hotline’s, not this file’s.

Every site on the San Luis Obispo board

San Luis Obispo County Environmental Health Services samples, in its own words, “nineteen locations along the coast on a weekly basis”, all year; fifteen of them reach the State Water Board file under the county’s name, and those are the rows here. The county files promptly — when this was written every site’s newest sample was the same date, two weeks old, the freshest of any county on this coast. An advisory, the county says, “spans fifty (50) yards north and south of the area where the sample is collected”, and its standing rain advisory is 72 hours after significant rain. San Simeon to Oceano, north to south.

The county’s Beach Water Quality Status Hotline is (805) 788-3411, updated when weekly results come in, and it is the answer when this page and the county disagree: what the tile shows is a measurement against the state’s limit, and posting a beach is the county’s.

Every site on the Santa Barbara board

Santa Barbara County Environmental Health Services has sampled its beaches every week, all year, since 1996 — in the county’s words, “In September 1996, Environmental Health Services began weekly year-round testing” — and files with the State Water Board. Sixteen sites reach that file; fourteen are on this board’s shore and are the rows here. The other two, Jalama Beach and the Guadalupe Dunes, are on the county’s west coast beyond Point Conception, where no town on the board is, and are on the county’s own map. Refugio and El Capitan are the state beaches on the Gaviota coast, nine and twelve miles from Gaviota, and read from that row. When this was written every site’s newest sample was ten days old. Gaviota to Carpinteria, west to east.

The county’s 24-hour recorded Ocean Water Quality Hotline is (805) 681-4949, and it is the answer when this page and the county disagree: what the tile shows is a measurement against the state’s limit, and posting a beach is the county’s.

Every site on the Ventura board

Ventura County Environmental Health has run its own program since 1998, and in its own words “40 sites are sampled during the Dry-Weather season (April to October), and 19 sites are sampled during the Wet-Weather season (November to March)”; results go up “no later than each Thursday by 5:00 p.m.” Thirty-six sites reach the State Water Board file; thirty-two are on this board’s shore and are the rows here. The four at Point Mugu and past it on the Malibu side are the base’s and the state park’s, with no town to belong to, and are on the county’s own map; so is Emma Wood’s wet-season history. A long beach is two, three or four points and each row says which. The Rincon coast to Ormond Beach, west to east.

The county’s Ocean Water Quality Hotline is (805) 662-6555, and it is the answer when this page and the county disagree: what the tile shows is a measurement against the state’s limit, and posting a beach, fifty yards either side of the sign, is the county’s.

Every site on the Los Angeles board

Four programs sample this shore and two of them reach the State Water Board file, so the board reads those two. The county’s Department of Public Health, in its own words, “collects ocean water samples from the mainland, once a week throughout the year” and “an additional five samples from Avalon on Santa Catalina Island beginning in April through October”. The city of Long Beach runs its own program and files its own points, sampled, in the city’s words, “three times a week”. The Beach Cities and the City of Los Angeles’ sanitation bureau sample too, and their sites are on the county’s own map but not in the state file. That leaves fifty-eight rows: forty-three of the county’s forty-five codes (two have stopped — one at Malibu last sampled in May 2025, one at Will Rogers last sampled in January 2026 — and are left off) and Long Beach’s fifteen. The file names fifteen county points “Malibu Beach” and fifteen city points “Long Beach”, so each row carries the program’s own station code. Palos Verdes and San Pedro have no site in the file; those two rows show the nearest one with its distance and send you to the county’s map. Leo Carrillo to Long Beach, west to east, then Avalon.

The county’s Beach Advisory Hotline is (800) 525-5662, updated as conditions change, and Long Beach’s Ocean and Bays Hotline is (562) 570-4199. They are the answer when this page and the agency disagree: what the tile shows is a measurement against the state’s limit, and a posting or a closure is the agency’s call.

Every site on the Orange board

The County of Orange Health Care Agency publishes its own map, current, at ocbeachinfo.com, and the board reads that map rather than the State Water Board file, whose newest Orange County result was seven weeks old the day this was written. Each site on the map carries the county’s own colour and sentence: green, “Ocean water bacteria levels meet state health standards”; a warning where bacteria exceed them, posted with the date; a closure for sewage or contaminated water; and grey for no recent data, which the tile shows as Check, never as clean. Under the map the county lists its closures, warnings and runoff advisories in words, and the tile carries those words beside the site they name. The county updates the map “when a change of status occurs”, not on a clock, so the tile is dated by our check. One hundred and thirty-nine sites, each on its nearest row — Newport Bay, Huntington Harbour and Dana Point Harbor included, because the county samples where people swim and paddle in the harbours too. Seal Beach to San Clemente, north to south.

The county’s Ocean and Bay Posting and Closure Status line is (714) 433-6400, and it is the answer when this page and the county disagree.

Every site on the San Diego board

The County of San Diego’s Department of Environmental Health and Quality samples the coast and the bays and publishes its postings in an application at sdbeachinfo.com, which loads its data only in a browser. Its sample results reach the State Water Board file, and that is what the board reads: fifty-four sites, Oceanside to the Tijuana Slough and Border Field, each with the county’s station code. The day this was written the north county sites had results from mid-September and La Jolla to the border had nothing newer than late August; the tile says how old each one is. Postings are the county’s, not the file’s, and on this coast they matter more than anywhere: the Tijuana River closes Imperial Beach and the Silver Strand for long stretches, and a closure is not a sample. Check sdbeachinfo.com or the county’s status line before you go in there. Left off: one Oceanside pier point last sampled in June, and the three Baja California points.

The county’s Beach and Bay Status Report is (619) 338-2073, for the beaches posted today.

The three bacteria, and what the numbers mean

This section and the next two are Humboldt County’s programme, in its own terms: its limits, its signs and its rain rule. Every other county’s programme is described under its own board above, and its hotline is below.

Every sample is tested for three indicator bacteria. None of them is itself the thing that makes you ill — they are indicators, bacteria whose presence means the water has had sewage or animal waste in it recently, and therefore may carry something that will.

MPN is “most probable number” — an estimated bacterial count per 100 millilitres of water. There is a fourth rule as well: the fecal-to-total coliform ratio exceeding 0.1 while total coliform is over 1,000 MPN.

“<10” is not zero. It means the laboratory found none at its detection limit. The tile prints it the way the county does rather than rounding it to a number nobody measured.

Failing any one of those standards puts the beach on warning status. The tile shows the county’s own verdict for each bacterium, not a calculation of our own.

Warning and closed are not the same thing

Signs come down when later samples show the bacteria are no longer there.

A closure is not a sampling result, so it never appears in the county’s results table — it appears as a sentence above it. That is why the tile reads that sentence separately, and why any wording it does not recognise is treated as something to go and read, never as an all-clear.

Rain beats the weekly sample

What the chips mean

• No warning — the latest sample was under all three limits, and the county lists no posting. The date and the three counts are printed beside it so you can see how close it was.
• Warning — a sample failed. The tile names which bacterium and by how much, and tells you how far back to stay.
• Check — something did not read cleanly: a bacterium with no verdict published, a beach missing from the latest run, or a posting notice in wording this board does not know. It is not a warning and it is certainly not an all-clear.
• Not monitored — nobody samples this beach.

Who to ring

Sources

• Humboldt County water quality test results — the table the tile reads
• Humboldt County Ocean Monitoring Program — the season, the five sites and the posting rules
• State Water Board: beach monitoring by county — the sixteen counties, and the absence of Del Norte
• State Water Board: California beach water quality
• San Luis Obispo County: beach water quality monitoring — the nineteen sites, the weekly cadence, the fifty-yard posting rule and the hotline
• Ventura County: Ocean Water Quality Monitoring Program — forty sites in the dry season, nineteen in the wet, and the hotline
• Los Angeles County Public Health: beach water quality — weekly on the mainland, five Avalon sites April to October, and the hotline
• City of Long Beach: ocean water monitoring — three times a week, and the hotline
• County of Orange Health Care Agency: OC Beachinfo — the map the tile reads, the closures, warnings and advisories, and the status line
• County of San Diego: sdbeachinfo.com — the county’s postings and closures, and the status line
• Santa Barbara County: Ocean Water Monitoring Program — weekly since 1996, and the hotline
• California beach water quality postings and closures — the statewide file Mendocino’s postings go into, last updated March 2026
• State Water Board: Safe to Swim — where Mendocino’s five weekly results are read