California Red Tide Status

Q: Is there red tide in California right now?

CDPH Marine Biotoxin Monitoring Program publishes the current California status on its own site and is linked on this page. This page carries when blooms normally happen here, which organisms are monitored, and the agency contacts to check before you go.

Q: Who monitors harmful algal blooms in California?

CDPH Marine Biotoxin Monitoring Program, CDPH Biotoxin Information Line. CDPH Marine Biotoxin Monitoring Program year round monitoring. The annual quarantine runs May 1 to October 31 and CDPH can start it early or extend it.. Each of them is linked on this page, with a phone number where one is published.

Q: Does clear water mean there is no bloom in California?

No. The organisms monitored in California do not have to discolour the water to reach the levels an agency acts on, and the toxins involved are invisible, tasteless, and not removed by cooking. Every agency on these pages says some version of the same thing: what the water looks like is not the test, and the published status is.

Q: How often is the California status updated?

California Department of Public Health states: "CDPH maintains a year-round monitoring program for these toxins in shellfish, as well as for the phytoplankton species that produce these toxins." That is the cadence to plan around. For the situation today, the agency's own page and phone line are the answer.

What CDPH Marine Biotoxin Monitoring Program is reporting today, reproduced as issued, and when blooms normally happen on this coast.

California bloom season normally runs May 1 to October 31

Usual bloom season

May 1 to Oct 31

Monitored by

Live agency feeds

Link only

California bloom status at a glance

Agency directory

Today

When blooms normally happen in California, from the agency wording quoted below. The bar is the usual peak stretch, not a forecast, and a bloom outside it is not unusual.

None reported

highest category reported

published by the agencies below

agencies that publish status

each linked below

June 15 to September 30

usual peak stretch

inside the season today

organisms monitored

Alexandrium, Pseudo-nitzschia

California does not get Florida style red tide. What it gets is biotoxin in shellfish, and the agency response is a calendar rather than a map: a statewide quarantine on sport harvested mussels every year from May 1 to October 31, which CDPH can start early or extend. That makes California the most predictable state on these pages and the one where a page is most useful months ahead.

Live, as issued

What the agencies are reporting in California right now

Every value below is reproduced from the agency that issued it, exactly as that agency wrote it, with the time attached. On a health subject the official category is the answer, and it can change from one sampling site to the next a few miles down the same coast.

Every status below is the issuing agency’s own, with the agency named and the time attached. Whether a beach is open, whether shellfish can be harvested, and any health question are answered by the agency listed for your state. If you are having trouble breathing, call a doctor.

Current California status is published by CDPH Marine Biotoxin Monitoring Program on its own site. It and the other agencies listed further down are where to check before you go.

Season

When blooms normally happen in California

“The annual quarantine is normally in effect from May 1 through October 31. However, the California Department of Public Health (CDPH) may begin the quarantine early, or extend it, if monitoring results indicate the presence of dangerous levels of biotoxins outside of the normal quarantine period.”California Department of Public Health, source

CDPH says the May to October quarantine period encompasses more than 99 percent of all PSP illnesses and deaths reported in California since 1927, which is about as clear a seasonal signal as any agency on these pages publishes. It also says outright that you should never assume mussels are safe outside it.

How often the agency samples

“CDPH maintains a year-round monitoring program for these toxins in shellfish, as well as for the phytoplankton species that produce these toxins.”California Department of Public Health, source

Hundreds of dead fish scattered along the wrack line of a long empty sand beach, running away to the horizon — A harmful algal bloom fish kill on the Gulf coast, photographed by the National Park Service at Padre Island National Seashore in Texas. FWC associates possible fish kills with its low category, more than 10,000 cells per litre, and probable fish kills from its medium category upward. Dead fish on the sand are one of the most reliable signs available to someone standing on a beach. “Marine Harmful Algal Bloom - Fish Kill” — National Park Service — Public domain

In the agency’s own words

The sentence CDPH Marine Biotoxin Monitoring Program most wants you to read

Reproduced verbatim, in the agency’s own words.

“You should never assume that sport-harvested mussels are safe to eat when the annual quarantine is not in effect. The toxins can occur at any time, which is why CDPH continues to monitor for them throughout the year.”California Department of Public Health, source

Where it concentrates

Which part of the California coast, and what you would notice

What people actually notice

The calendar rather than the water: the California quarantine is a fixed annual window that CDPH can extend, and none of it is visible from the beach
Sea lions in distress on the sand, which is the sign most often associated with domoic acid events on this coast
A CDPH advisory naming your county, which is issued separately from the statewide quarantine and can arrive at any time of year
Nothing at all, which is the point: CDPH states that toxins can occur at any time and that clear water proves nothing

Beaches worth checking the status for

Bodega Bay and the Sonoma Coast

Sonoma County. A heavily used recreational mussel and clam stretch on the north coast, well inside the annual quarantine footprint.

Half Moon Bay and Pillar Point

San Mateo County. Rocky intertidal within reach of the Bay Area, which makes it one of the most harvested stretches in the state.

Monterey Bay

Monterey and Santa Cruz Counties. The bay most associated with Pseudo-nitzschia and domoic acid events on the California coast, and the one with the longest research record.

Morro Bay and the San Luis Obispo coast

San Luis Obispo County. A county CDPH has named in its own recreational bivalve advisories, separately from the statewide quarantine.

Santa Barbara and the Channel Islands coast

Santa Barbara County. A southern California stretch where domoic acid events have repeatedly been linked to marine mammal strandings.

A man in chest waders standing knee deep in the surf, filling a sample bottle with seawater — Coastal water sampling, photographed for the US Environmental Protection Agency at Grand Isle State Park in Louisiana. Every category on this page starts as a bottle of water like this one. FWC’s statewide counts come from routine monitoring, event response and partner sampling, which is why coverage is uneven and why an unsampled county is a gap in sampling rather than a statement about its water. “June 4, Collecting water for testing at Grand Isle State Park, La” — U.S. EPA (photo by Eric Vance) — Public domain

Shellfish closures

California shellfish harvest closures

Shellfish harvest closures

Harvest closures are legal orders issued by a state health or agriculture department, and they change without warning. The current closure status is published by the agency below. Check it directly, every time, on the day you are going.

California is the one state in this set where the shellfish calendar is the whole story. The annual quarantine on sport harvested mussels runs the length of the coast from the Oregon border to the Mexican border, including bays, inlets and harbours, and it applies to recreational harvest rather than to commercially grown product.

California Department of Public Health, Marine Biotoxin Monitoring Program · Official closure information · 800-553-4133

The agency’s own published guidance on harvest safety, quoted:

“If any sample exceeds the federal alert level for the PSP or domoic acid toxins, then that area is immediately closed to harvesting until conditions become safe.”California Department of Public Health, source

That sentence concerns monitored commercial product, not anything harvested recreationally, and recreational harvest is exactly what the closure orders exist for.

A posted algae advisory sign on a Lake Erie beach in Ohio, with an orange warning placard reading that high levels of algal toxins have been detected — A posted advisory on a Lake Erie beach in Ohio, carrying an orange placard reading “high levels of algal toxins have been detected”. Different lake and a different organism from Florida red tide, but the principle is the one that matters everywhere: the sign in front of you was put there by people who looked at that specific water today, and it outranks anything on a screen, including this page. “Algae warning sign (16832101051)” by NOAA Great Lakes Environmental Research Laboratory, CC BY-SA 2.0

Who to ask

Who to contact in California

Health questions, whether a specific beach is open, and anything to do with harvesting are answered by these agencies. Each is linked, with a phone number where one is published.

CDPH Marine Biotoxin Monitoring Program

Runs year round phytoplankton and shellfish biotoxin monitoring for the whole California coast, sets the annual sport harvest mussel quarantine, and issues the recreational bivalve shellfish advisories. This is the agency that answers every question on this page.

Year round monitoring. The annual quarantine runs May 1 to October 31 and CDPH can start it early or extend it.

Official page · 800-553-4133

CDPH Biotoxin Information Line

A recorded line CDPH points the public to for updates on current quarantines and health advisories throughout the year. This is the number to ring before harvesting anything, every time.

Official page · 800-553-4133

What each organism here does

Alexandrium, the dinoflagellate behind paralytic shellfish poisoning. Produces saxitoxins, which agencies associate with paralytic shellfish poisoning.
Pseudo-nitzschia, a group of marine diatoms. Produces domoic acid, which agencies associate with amnesic shellfish poisoning, also called domoic acid poisoning.

Common questions

California red tide FAQ

Is there red tide in California right now?

When is red tide season in California?

California Department of Public Health states: "The annual quarantine is normally in effect from May 1 through October 31. However, the California Department of Public Health (CDPH) may begin the quarantine early, or extend it, if monitoring results indicate the presence of dangerous levels of biotoxins outside of the normal quarantine period." On that basis the usual stretch runs May 1 to October 31, with the busiest weeks June 15 to September 30. CDPH says the May to October quarantine period encompasses more than 99 percent of all PSP illnesses and deaths reported in California since 1927, which is about as clear a seasonal signal as any agency on these pages publishes. It also says outright that you should never assume mussels are safe outside it. That is a climatological typical and not a forecast: blooms happen outside it, and some years produce very little.

Can you swim during a red tide in California?

California Department of Public Health publishes this wording: "You should never assume that sport-harvested mussels are safe to eat when the annual quarantine is not in effect. The toxins can occur at any time, which is why CDPH continues to monitor for them throughout the year." That is the agency's sentence, quoted, and the agency is the authority. Whether a particular spot is open on a particular day is decided by the people posting signs at the access point, who looked at that specific water today.

Who monitors harmful algal blooms in California?

Does clear water mean there is no bloom in California?

Is it safe to eat shellfish from California during a bloom?

Harvest closures are legal orders issued by California Department of Public Health, Marine Biotoxin Monitoring Program, they change without warning, and getting one wrong is a hospital matter. Check California Department of Public Health, Marine Biotoxin Monitoring Program directly, on the day, every time. California is the one state in this set where the shellfish calendar is the whole story. The annual quarantine on sport harvested mussels runs the length of the coast from the Oregon border to the Mexican border, including bays, inlets and harbours, and it applies to recreational harvest rather than to commercially grown product.

Does a quiet year mean blooms are over in California?

No. California Department of Public Health's own framing is that these are recurring events rather than one-off ones, and the monitoring programmes behind them run whether or not there is anything to find. A season with little to report is a normal part of the pattern rather than the end of it, which is why this page leads with when blooms normally happen and only then shows what is being reported today.

How often is the California status updated?

What is the difference between red tide and blue-green algae?

Red tide means a marine bloom, in the Gulf of Mexico usually Karenia brevis, which produces brevetoxins and causes respiratory irritation carried in sea spray. Blue-green algae means freshwater cyanobacteria such as Microcystis, which bloom in lakes and slow rivers and produce a different family of toxins. Different organisms, different water, different monitoring programmes, and a status for one says nothing about the other. This page covers PSP and domoic acid biotoxins.

Plan the rest of the trip

More for a California coast day

California beach conditionsRip current and swim risk from the NWS surf zone forecast. A different hazard, a different agency, the same beach.California mosquito forecastCoastal marsh and dune ponds are mosquito habitat, and evening at the water is prime biting time.Red tide across the countryEvery state with a monitored bloom, which agency publishes it, and what they are reporting now.

Red tide and algal blooms in other states

Season windows are climatological typicals drawn from the agency quotations above, not forecasts. Whether a beach is open and whether shellfish can be harvested are answered by the agencies named above. National picture: red tide and algal bloom status across the country →
Hero image: “2018 Fort De Soto - South Beach” by Beyond My Ken, CC BY-SA 4.0