Give Now

Delays, Closings and Severe Weather - View All Alerts and Updates

Warm Weather Creating Ideal Conditions For Harmful Algae

If you’re thinking about a nice refreshing dip in the pool, you may want to think again.

“Right now were around 90 degrees in the main pool,” said Rob Gilchrist, Aquatics Coordinator with the Bloomington Parks and Recreation Department.

Bryan Park Pool has seen those water temperatures for nearly 2 weeks.

“Unfortunately with the evening’s temperatures not dropping significantly, the water doesn’t really get a chance to cool down and of course it does sit through the entire day baking in the sun,” said Gilchrist.

But pool water baking in the sun is much different then say, lake water baking in the sun. Blue-green algae, or cyanobacteria, thrives when water remains warm and is high in nutrients like phosphates and nitrates. With higher cell counts is a higher likelihood the algae cells will produce toxins harmful to both humans and animals.

“There could be some dermal toxicity so your skin could get irritated, you could have some rashes,” said Melissa Clark, a lecturer with Indiana University’s School of Public and Environmental Affairs. “There are some that produce a neurotoxin and some produce liver toxins.”

On July 19th the Paynetown State Recreation Area at Monroe Lake was tested and surpassed the cautionary limit of 100,000 cells per milliliter of water, set by the Indiana Department of Environmental Management. That doesn’t necessarily mean its not safe to swim, only that IDEM will continue to monitor the situation. Clark noted there are over 100 varieties of blue-green algae and not all produce harmful toxins.

The greatest danger comes from bodies of water that aren’t tested, such as neighborhood retention ponds which are designed to hold nutrient rich runoff making them ideal for large algae populations. Human and animal deaths from algal toxins are not uncommon.

“Take a precautionary approach to it. If you come up to the pond, and it looks really green and your thinking ‘I definitely don’t want to get in to it’, its probably not a good idea to let your dog drink from it,” said Clark.

Don’t let your children or animals play in small ponds and make sure you pay attention to warnings at recreational swimming areas. More information about the Indiana Department of Environmental Managements findings can be found at

Want to contact your legislators about an issue that matters to you? Find out how to contact your senators and member of Congress here.

What is RSS? RSS makes it possible to subscribe to a website's updates instead of visiting it by delivering new posts to your RSS reader automatically. Choose to receive some or all of the updates from Indiana Public Media News:

Support For Indiana Public Media Comes From