Lake Rowena algae bloom status

Lake Rowena algae bloom history

Florida's Department of Environmental Protection sampled Lake Rowena 35 times between 2021 and 2025. Staff saw a bloom on 31 visits (89%).

The highest microcystin result recorded here was 3.3 µg/L, below the US EPA swimming advisory level of 8 µg/L.

Blooms have been recorded every year for the last 3 years in the data.

That puts Lake Rowena in the top 15% of the 293 Florida lakes on this site for the number of years with blooms.

When do algae blooms happen at Lake Rowena?

At Lake Rowena, reports are most often logged in May, June and July.

About 71% of reports fall between May and September, when warm, calm, sunny weather lets blue-green algae multiply.

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

Recent Lake Rowena algae reports

What the Florida results mean

Florida records whether staff saw a bloom at each visit and, when a sample is tested, how much microcystin it contained.

Bloom seen

Staff saw a bloom at the sampling site, and no toxin was found or tested.

Toxin detected

Microcystin, a liver toxin made by blue-green algae, was found in the sample.

8 µg/L or more

At or above the level where the US EPA recommends swimming advisories.

Is Lake Rowena 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 3 different years here, take particular care at Lake Rowena in May, June and July.

• 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

• Lake Sue1 km away, 30 reports, last in 2025
• Lake Estelle1 km away, 18 reports, last in 2023
• Lake Formosa1 km away, 18 reports, last in 2025
• Lake Chelton1 km away, 7 reports, last in 2022
• Lake Ivanhoe2 km away, 13 reports, last in 2022

All Orange County lakes with algae reports

Questions about Lake Rowena

Is there algae in Lake Rowena right now?

Florida's most recent sample from Lake Rowena, on 2 January 2025 at Lake Rowena - W Shore, found no visible bloom and microcystin toxin measured 0.26 µg/L, below the US EPA swimming advisory level of 8 µg/L. Florida publishes its data in yearly batches, so for today's conditions check the DEP Algal Bloom Dashboard and the signs at the shore.

When was the last algae bloom at Lake Rowena?

The most recent entry in Florida's data is from 2 January 2025 at Lake Rowena - W Shore: a sample with no bloom seen.

Has Lake Rowena had toxic algae before?

Yes. Blooms are recorded in 3 of the 5 years from 2021 to 2025, most often in May, June and July.

Can dogs swim in Lake Rowena?

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 Lake Rowena 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.