Mission Lake algae bloom status

Mission Lake algae bloom history

The Kansas Department of Health and Environment has tested Mission Lake 25 times since 2012, usually after someone reported a possible bloom. 8 samples (32%) reached at least Watch level, and 1 reached Warning level or higher.

That puts Mission Lake in the top 20% of the 145 Kansas lakes on this site for the number of years with blooms.

When do algae blooms happen at Mission Lake?

At Mission Lake, reports are most often logged in June, August and September.

About 100% 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 Mission Lake algae reports

What the Kansas results mean

KDHE sets each advisory from lab results or what staff see at the lake. Samples on this page are labelled with the level their results reached.

Watch

A bloom is visible, microcystin is above 4 µg/L, or there are more than 80,000 cyanobacteria cells per mL. Avoid algae and keep people and pets from swimming near it or drinking the water.

Warning

Microcystin above 8 µg/L, more than 250,000 cells per mL, or heavy surface scum. Avoid all contact with the water, including fishing and boating.

Hazard

Microcystin above 2,000 µg/L or more than 10 million cells per mL. KDHE recommends closing all or part of the lake and sometimes the shore nearby.

Is Mission Lake 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 Mission Lake in June, August and September.

• 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

• Atchison County Park Lake7 km away, 27 reports, last in 2025
• Hiawatha City Lake17 km away, 33 reports, last in 2026
• Brown County State Fishing Lake23 km away, 25 reports, last in 2021
• Elkhorn Lake29 km away, 15 reports, last in 2026
• Atchison County State Fishing Lake30 km away, 24 reports, last in 2025

All Brown County lakes with algae reports

Questions about Mission Lake

Is there algae in Mission Lake right now?

Kansas has no current advisory for Mission Lake. The most recent sample, on 24 August 2026, was below advisory levels (microcystin 0.34 µg/L, 52,248 cyanobacteria cells/mL). This site checks KDHE's advisory list every day, but lakes are only sampled after a bloom is reported, so for today's conditions check the KDHE algae bloom map and the signs at the shore.

When was the last algae bloom at Mission Lake?

The most recent entry in Kansas's data is from 24 August 2026: a sample below advisory levels (microcystin 0.34 µg/L, 52,248 cyanobacteria cells/mL).

Has Mission Lake had toxic algae before?

Yes. Blooms are recorded in 5 of the 15 years from 2012 to 2026, most often in June, August and September.

Can dogs swim in Mission Lake?

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 Mission Lake 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.