Is the lake safe?

Humboldt County, California

Big Lagoon Hydrologic Area algae bloom status

No recent reports

Checked against state data on 24 October 2026

Is Big Lagoon Hydrologic Area safe to swim in?

There are no bloom reports for Big Lagoon Hydrologic Area in the last 30 days of California's data. The most recent was a bloom report on 21 March 2022 at Lagoonwide. Blooms are a recurring problem here: toxic algae has been reported every year from 2018 to 2022, most often in January, March and June.

No recent report isn't the same as safe, because most lakes are only checked occasionally. Look at the water and the signs before you swim.

Check today on the California HABs Portal map
Years with blooms
5 of 5
Usual months
Jan, Mar and Jun
Advisories issued
3
Data checked
24 October 2026
See it on the California map

Big Lagoon Hydrologic Area algae bloom history

California's Water Boards hold 5 bloom reports for Big Lagoon Hydrologic Area going back to 2018. Reports came in every year since then.

State staff recommended an advisory 3 times: 2 Warning and 1 Caution. Warning is the middle level and means toxins were high enough to advise against swimming.

Blooms have been recorded every year for the last 5 years in the data.

That puts Big Lagoon Hydrologic Area in the top 20% of the 318 California lakes on this site for the number of years with blooms.

  1. 2018 1 report
  2. 2019 1 report
  3. 2020 1 report
  4. 2021 1 report
  5. 2022 1 report
Warning advisoryCaution advisoryReported, no advisory level

When do algae blooms happen at Big Lagoon Hydrologic Area?

At Big Lagoon Hydrologic Area, reports are most often logged in January, March and June.

Reports are spread across the year, with 60% between May and September.

Blooms can appear, move with the wind and fade within hours or days, so the time of year is only a guide.

January: 20% of reports
February: 0% of reports
March: 20% of reports
April: 0% of reports
May: 0% of reports
June: 40% of reports
July: 20% of reports
August: 0% of reports
September: 0% of reports
October: 0% of reports
November: 0% of reports
December: 0% of reports
Share of reports by month. Darker bars are the peak months.

Recent Big Lagoon Hydrologic Area algae reports

Recent reports came from 3 different locations around Big Lagoon Hydrologic Area, including Lagoonwide, Big Lagoon and Big Lagoon - Campground. A bloom in one cove or beach doesn't mean the whole lake is affected, and conditions can differ a short distance away.

DateLocationResult
21 March 2022 Lagoonwide Bloom reported
1 June 2021 Waterbody name submitted:Grizzly Creek Campground Redwoods State Park;Landmark submitted:N Bloom reported
10 January 2020 Big Lagoon Warning
12 June 2019 Big Lagoon Warning
12 July 2018 Big Lagoon - Campground Caution

What the California results mean

California recommends one of three advisory levels when a bloom is checked, matched to the signs posted at the shore.

Caution
Toxins may be present. Stay away from scum and keep pets and livestock from drinking the water.
Warning
Toxins are at higher levels. No swimming, and keep children and pets away from the water.
Danger
High toxin levels. Stay out of the water and off the shore until further notice.
Bloom reported
A bloom was reported, often by a member of the public, without a formal advisory level.

Is Big Lagoon Hydrologic Area safe for dogs?

Dogs are at the greatest risk from toxic algae. They swallow water while swimming, eat scum on the shore and lick algae off their fur afterwards, and a small amount can kill a dog within hours. With blooms recorded in 5 different years here, take particular care at Big Lagoon Hydrologic Area in January, March and June.

  • Keep your dog on a lead near water that looks green, scummy, foamy or discoloured, and away from algae washed up on the shore.
  • If your dog gets in, rinse it straight away with clean water and don't let it lick its coat.
  • Call a vet immediately if your dog vomits, drools, has diarrhoea, staggers, shakes or seems weak after being near the water.

Read the full guide to toxic algae and dogs: symptoms, what to do in the first minutes and how vets treat it.

Health effects of toxic algae

Blue-green algae (cyanobacteria) can produce toxins that affect the liver, nervous system and skin. Swallowing water during a bloom can cause stomach pain, vomiting and diarrhoea. Skin contact can cause rashes, and breathing spray from the water can irritate the eyes, nose and throat. Children are at higher risk because they are smaller and more likely to swallow water.

How to spot a bloom

Toxic blooms can look like pea soup, spilled paint or green streaks on the surface, and they can also be blue, brown, white or red. Scum often collects along the shore downwind. If you can't see your feet in knee-deep water, or you aren't sure, stay out.

Don't drink untreated lake water, and don't boil it to make it safe: boiling doesn't destroy algal toxins. If you feel unwell after contact with the water, contact a doctor or Poison Control on 1-800-222-1222.

Nearby lakes with algae reports

All Humboldt County lakes with algae reports

Questions about Big Lagoon Hydrologic Area

Is there algae in Big Lagoon Hydrologic Area right now?

There are no bloom reports for Big Lagoon Hydrologic Area in the last 30 days of California's data. The most recent was a bloom report on 21 March 2022 at Lagoonwide. California's data is checked every day, so for today's conditions check the California HABs Portal map and the signs at the shore.

When was the last algae bloom at Big Lagoon Hydrologic Area?

The most recent entry in California's data is from 21 March 2022 at Lagoonwide: a bloom report.

Has Big Lagoon Hydrologic Area had toxic algae before?

Yes. Blooms are recorded every year from 2018 to 2022, most often in January, March and June.

Can dogs swim in Big Lagoon Hydrologic Area?

Keep dogs out of the water whenever a bloom is reported or the water looks green, scummy or discoloured. Dogs are the animals most often killed by algal toxins because they swallow water and lick their fur. If your dog swims in water that might have algae, rinse it with clean water and call a vet if it vomits, drools, staggers or seems weak.

Can you eat fish caught in Big Lagoon Hydrologic Area during a bloom?

If you keep fish caught during a bloom, health agencies advise removing the guts and liver and rinsing the fillets in clean water before cooking, because toxins collect most in the organs. Some agencies advise not eating fish from an active bloom at all, so follow local guidance.

About this data

This page uses official records from the California State Water Resources Control Board, which updated daily. Reports are grouped by waterbody. The site was last rebuilt on 24 October 2026.

States only test some lakes, some of the time, so a lake without a recent report hasn't necessarily been checked. This page is independent, isn't affiliated with the State of California, and isn't health advice. View the source data.