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Maine Red Tide Status

What Maine Department of Marine Resources, Public Health Bureau is reporting today, reproduced as issued, and when blooms normally happen on this coast.

Maine bloom season normally runs April 1 to October 31
Usual bloom season
Apr 1 to Oct 31
Monitored by
2
Live agency feeds
Link only

Maine bloom status at a glance

Agency directory
Today
When blooms normally happen in Maine, 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
2
agencies that publish status
each linked below
May 15 to August 31
usual peak stretch
inside the season today
3
organisms monitored
Alexandrium, Pseudo-nitzschia, Dinophysis

Maine has the best documented harmful algal bloom season of any state on these pages. DMR publishes three separate timing facts on one page: blooms typically April to October, weekly testing March through October, and precautionary closures starting every May. That is exactly the kind of thing that stays true in a year with no bloom at all.

Live, as issued

What the agencies are reporting in Maine 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 Maine status is published by Maine Department of Marine Resources, Public Health Bureau 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 Maine

“Harmful algal blooms in Maine typically occur between April and October, but the species of phytoplankton that causes Amnesic Shellfish Poisoning, Pseudo-nitzschia, has bloomed in recent years during winter months.”Maine Department of Marine Resources, source

DMR gives the usual window as April to October and starts precautionary closures every May as a matter of course, which makes Maine the most predictable Northeast state here. The caveat DMR itself adds matters just as much: Pseudo-nitzschia has bloomed in recent winters, well outside that window.

How often the agency samples

“The State of Maine, Department of Marine Resources Public Health Bureau tests coastal shellfish areas for biotoxins weekly, beginning in March and going through October, or later when necessary.”Maine Department of Marine Resources, 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 Maine Department of Marine Resources, Public Health Bureau most wants you to read

Reproduced verbatim, in the agency’s own words.

“Precautionary regional closures along the coast are implemented annually starting in May when the likelihood of biotoxin blooms increases with the temperature.”Maine Department of Marine Resources, source
Where it concentrates

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

What people actually notice

  • The calendar first, since DMR starts precautionary regional closures every May regardless of what any particular week looks like
  • A winter Pseudo-nitzschia closure, which DMR says has happened in recent years and which falls right outside the April to October window
  • The difference between the monthly classification map and the daily closure list, which is the single easiest mistake to make here
  • Nothing in the water, because DMR states that toxic shellfish can be found in clear, clean and remote waters

Beaches worth checking the status for

Casco Bay

Cumberland County. The most heavily harvested clam flats in southern Maine, close enough to Portland that a closure affects a lot of people at once.

Muscongus Bay and the Damariscotta River

Lincoln County. Maine’s densest oyster growing area, where biotoxin closures land on aquaculture and recreational harvest together.

Penobscot Bay

Knox and Waldo Counties. A wide midcoast bay whose closure areas are split into several separate stretches that can differ from each other on the same day.

Frenchman Bay and Mount Desert Island

Hancock County. The stretch most visitors reach through Acadia, where the flats look pristine and the DMR closure status still applies.

Cobscook Bay

Washington County. Far Downeast, with some of the largest tides in the country and its own biotoxin closure history.

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
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Shellfish closures

Maine 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.

DMR draws a distinction worth carrying: the classification map is updated on the first of every month, but closures themselves can change on a daily basis. If you are asking whether a flat is open today, the closure list and the local Marine Patrol office are the answer and the monthly map is not.

Maine Department of Marine Resources, Public Health Bureau · Official closure information

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 Maine

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.

Maine Department of Marine Resources, Public Health Bureau

Tests the Maine coast for biotoxins, issues every shellfish closure in the state, and publishes both the closure list and the interactive closure map. DMR is the only authority on whether an area is open.

Weekly testing beginning in March and running through October, or later when necessary. Closures can change on a daily basis.

Official page · 207-624-6550

Maine DMR shellfish closure map

The interactive map of current closures and aquaculture leases. DMR warns that the public health water classifications on it are updated on the first of every month while closures themselves can change daily, so the closure list rather than the map is what to read on the day.

Official page

What each organism here does

  • Alexandrium, what Maine calls red tide. 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.
  • Dinophysis, the dinoflagellate behind diarrhetic shellfish poisoning. Produces okadaic acid and related toxins, which agencies associate with diarrhetic shellfish poisoning.
Common questions

Maine red tide FAQ

Plan the rest of the trip

More for a Maine coast day

Maine beach conditionsRip current and swim risk from the NWS surf zone forecast. A different hazard, a different agency, the same beach.Maine 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

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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