Is the lake safe?

Osage County, Kansas

Overbrook City Lake algae bloom status

No current advisory

Checked against KDHE's advisory list on 24 October 2026

Is Overbrook City Lake safe to swim in?

Kansas has no current advisory for Overbrook City Lake. The most recent sample, on 17 June 2024, was below advisory levels (microcystin 0.34 µg/L, 4,589 cyanobacteria cells/mL). Blooms are a recurring problem here: toxic algae has been reported in 7 of the 9 years from 2016 to 2024, most often in June, August and September.

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 KDHE algae bloom map
Years with blooms
7 of 9
Usual months
Jun, Aug and Sep
Samples at Warning level or higher
12 of 28
Data checked
24 October 2026
See it on the Kansas map

Overbrook City Lake algae bloom history

The Kansas Department of Health and Environment has tested Overbrook City Lake 28 times since 2016, usually after someone reported a possible bloom. 21 samples (75%) reached at least Watch level, and 12 reached Warning level or higher.

The highest microcystin result was 10 µg/L, above KDHE's Warning threshold of 8 µg/L.

That puts Overbrook City Lake in the top 15% of the 145 Kansas lakes on this site for the number of years with blooms.

  1. 2016 6 samples, Warning
  2. 2017 7 samples, Warning
  3. 2018 5 samples, Warning
  4. 2019 2 samples, Warning
  5. 2020 None
  6. 2021 2 samples, Watch
  7. 2022 4 samples, Warning
  8. 2023 None
  9. 2024 2 samples, Warning
Warning levelWatch levelNo samples

When do algae blooms happen at Overbrook City Lake?

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

About 86% 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.

January: 0% of reports
February: 0% of reports
March: 0% of reports
April: 0% of reports
May: 0% of reports
June: 14% of reports
July: 14% of reports
August: 29% of reports
September: 29% of reports
October: 14% of reports
November: 0% of reports
December: 0% of reports
Share of reports by month. Darker bars are the peak months.

Recent Overbrook City Lake algae reports

DateLocationResult
17 June 2024 Not given Below advisory levels · microcystin 0.34 µg/L, 4,589 cyanobacteria cells/mL
3 June 2024 Not given Warning level · microcystin 0.43 µg/L, 1,221,921 cyanobacteria cells/mL
17 October 2022 Not given Below advisory levels · microcystin not detected, 6,014 cyanobacteria cells/mL
26 September 2022 Not given Watch level · microcystin 0.31 µg/L, 86,693 cyanobacteria cells/mL
6 September 2022 Not given Warning level · microcystin 0.16 µg/L, 333,428 cyanobacteria cells/mL
8 August 2022 Not given Watch level · microcystin 0.18 µg/L, 204,128 cyanobacteria cells/mL
9 August 2021 Not given Below advisory levels · microcystin not detected, 17,455 cyanobacteria cells/mL
12 July 2021 Not given Watch level · microcystin 1.51 µg/L, 109,299 cyanobacteria cells/mL
24 June 2019 Not given Below advisory levels · microcystin not detected, 44,867 cyanobacteria cells/mL
11 June 2019 Not given Warning level · microcystin 0.6 µg/L, 373,363 cyanobacteria cells/mL
15 October 2018 Not given Below advisory levels · microcystin not detected, 66,441 cyanobacteria cells/mL
1 October 2018 Not given Watch level · microcystin not detected, 236,202 cyanobacteria cells/mL

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 Overbrook City 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 7 different years here, take particular care at Overbrook City 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

All Osage County lakes with algae reports

Questions about Overbrook City Lake

Is there algae in Overbrook City Lake right now?

Kansas has no current advisory for Overbrook City Lake. The most recent sample, on 17 June 2024, was below advisory levels (microcystin 0.34 µg/L, 4,589 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 Overbrook City Lake?

The most recent entry in Kansas's data is from 17 June 2024: a sample below advisory levels (microcystin 0.34 µg/L, 4,589 cyanobacteria cells/mL).

Has Overbrook City Lake had toxic algae before?

Yes. Blooms are recorded in 7 of the 9 years from 2016 to 2024, most often in June, August and September.

Can dogs swim in Overbrook City 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 Overbrook City 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.

About this data

This page uses official records from the Kansas Department of Health and Environment (KDHE), which updated as samples come in, with advisories reviewed through the April to October season. 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 Kansas, and isn't health advice. View the source data.