Guide
Beach water: five beaches, and the rest of the coast
Checked September 18, 2026 against Humboldt County Environmental Health and the State Water Resources Control Board.
Two hundred miles of coast on this board, and five beaches are sampled. All five are in one twelve-mile stretch between the Mad River and Trinidad. Everything else — every beach in Del Norte County, Samoa, Centerville, the Lost Coast — has nobody testing the water at all.
An unmonitored beach is not a clean beach. It is a beach nobody looked at. Nobody samples Pebble Beach or Crescent Beach at Crescent City, Gold Bluffs Beach at Orick, Samoa Dunes, Centerville Beach at Ferndale, Mattole Beach at Petrolia or Black Sands Beach at Shelter Cove. They carry a grey chip on the tile rather than quietly sitting there with no warning beside them, which would read as a clean bill of health.
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.
The 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 this board
North to south, with the creek each sample is taken at, and whether anyone tests it.
| Beach | Where, and the creek | Monitored |
|---|---|---|
| Pebble Beach | Crescent City, Del Norte | No |
| Crescent Beach | Crescent City, Del Norte | No |
| Gold Bluffs Beach | Orick | No |
| Trinidad State Beach | Trinidad, at Mill Creek | Yes |
| Luffenholtz Beach | Trinidad, at Luffenholtz Creek | Yes |
| Moonstone Beach | Trinidad, at Little River | Yes |
| Clam Beach | McKinleyville, at Strawberry Creek | Yes |
| Mad River Mouth | McKinleyville, north side of the river | Yes |
| Samoa Dunes | Samoa, the North Spit | No |
| Centerville Beach | Ferndale | No |
| Mattole Beach | Petrolia, the Lost Coast | No |
| Black Sands Beach | Shelter Cove | No |
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 this coast than twelve, and none of those is monitored either.
The three bacteria, and what the numbers mean
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.
| What | Limit | What it indicates |
|---|---|---|
| Total coliform | 10,000 MPN | A large group that also lives naturally in water, soil and plants. A high count on its own means less than the other two. |
| E. coli | 400 MPN | A fecal coliform, from warm-blooded animals including people. The county tests E. coli rather than fecal coliform generally, because its own testing shows E. coli is essentially all of the fecal coliform in this region. |
| Enterococcus | 104 MPN | The one most closely tied to illness in salt water. |
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
| Warning | Closed | |
|---|---|---|
| Why | A sample failed one or more standards. | The County Health Officer’s decision, for an imminent threat such as a known discharge of pollutants. |
| The sign says | “Warning! Ocean Water Contact May Cause Illness! Bacteria Levels Exceed Health Standards” | “KEEP OUT. Sewage Contaminated Water. Contact with Water May Cause Illness” |
| Stay back | at least 50 yards from the creek mouth | at least a quarter of a mile (440 yards) from both sides of the creek mouth |
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
The county’s own advice: after heavy rainfall, avoid contact with ocean and creek water for at least three days. Stormwater carries bacteria straight into the creeks and out through the surf, and a sample taken last Tuesday cannot know about Saturday’s storm. This is the line most likely to matter on any given day, and it is on the tile for that reason.
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
| Humboldt County Environmental Health 100 H St., Suite 100, Eureka | 707-445-6215 800-963-9241 |
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