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Blue-Green Algae

Harmful Algal Blooms in Lakes and Reservoirs

Spotlight: Sampling

Indiana Reservoir and Lake Sampling

Spotlight: Board of Animal Health

BOAH Blue-Green Algae

Spotlight: Nonrule Policies

Fact Sheets

Spotlight: Notices

Indiana State Parks Advisories and Closings

Blue-Green Algae

Algae and specifically blue-green algae have been monitored by IDEM and other agencies to track the occurrence and spread of these algae in Indiana water bodies where human and animal contact is most prevalent.  Below are the links to test results for harmful algae and other resources that offer information on advisories and hazards, as well as ways to help reduce blue-green algae.

Reservoir and Lake Sampling and Test Results

IDEM, along with the Indiana Department of Natural Resources (DNR), the Indiana Department of Health (IDOH), and the Board of Animal Health (BOAH) are working together to provide information about blue-green algae in our lakes. IDEM samples selected swimming areas at some state parks and state recreation areas for blue-green algae and toxins between Memorial Day and Labor Day. The weekly results can be found within the Indiana Reservoir and Lake Sampling Update or on the map below.

Blue-green algae, also known as cyanobacteria, are a group of photosynthetic bacteria that have been around for billions of years and occur naturally in a wide range of waterbodies throughout Indiana, the United States, and the world. Not all blue-green algae (cyanobacteria) species produce toxins and the ones that can are not producing toxins all the time. The most common routes of exposure to cyanobacteria and their toxins occur either through ingestion or skin exposure. Humans can be exposed through accidental ingestion of water while recreating. Direct contact with cyanobacterial cells can also irritate the skin for sensitive people. This includes buildup of cyanobacterial cells and their toxins in bathing suits. Cyanotoxins can also kill livestock and pets that drink affected water. Additional exposure for animals includes eating algal mats or licking cyanobacteria or toxins off their fur. Exposure through inhalation is not as common in Indiana and this occurs when water containing cyanobacteria cells release toxins into the air.

IDEM scientists take water samples, identify and count blue-green algae, and analyze for four algal toxins:

The Lilly Center at Grace College collects water samples from open water on Kosciusko County’s twelve all-sport lakes and Center and Pike lakes, along with the public swimming beaches at Center, Pike, Syracuse, Waubee, Webster and Winona lakes. Samples are processed and analyzed for microcystin; a blue-green algae toxin relevant in the county. Toxin results will be updated on this page every week.

Latest Testing Results

DNR Beach Advisories

DNR Harmful Algae Bloom Alert Sign
DNR Blue Green Algae Sign

The DNR advises the public of the blue-green algae threat through signs at the swimming areas and on the DNR website for the properties being sampled. The Indiana State Parks Advisories and Closings page has the full list of these facilities.

Since the presence of harmful algae isn't always obvious and the effect of coming in contact with it is different for everyone, it is best to pay close attention to these signs. Just like everyone has different sensitivity to poison ivy, your response to blue-green algae is not predictable.

If you are recreating in a lake or other waterbody, don’t ingest the water, avoid contact with visible algae or algal scums, and shower or bathe with warm, soapy water when you are finished. If you think you are ill from contact, you need to contact your doctor for assistance and to report a human illness.

Hazards to Pets and Livestock

Veterinarians recommend not allowing pets and livestock to drink or swim in waters affected by algae. If in doubt, keep your animals out. Dogs are particularly susceptible to blue-green algae poisoning. If you think your animal is ill from contact, this is an emergency so call your veterinarian immediately. Details on what symptoms to track are provided on the BOAH Blue-Green Algae site.

Ways to Help Reduce Blue-Green Algae

Many ways exist to reduce or stop nutrient inputs into our waterways. Here are some simple things we can do right in our own backyards:

  • Most established lawns do not need phosphorus to be healthy. If applying fertilizer, use a phosphorus-free lawn fertilizer. This is critical if you live on a lake. Lawn-fertilizer packaging is labeled with three (3) numbers for nutrient content. A zero (0) as the middle number (phosphorus content) indicates a phosphorus-free fertilizer.
  • Do not over fertilize in your garden. Check soil nutrient levels prior to applying garden fertilizer to ensure correct application. Soil test kits can be purchased from some local hardware stores and through online distributors.
  • Do not fertilize up to the edge of a waterway. Check with your local government for any specific setback requirements.
  • Do not dispose of grass clippings or leaves in or near a waterway.
  • To prevent inputs from human waste, have your septic system inspected and tank pumped out at least every two years.
  • If conducting land disturbing activity, prevent soil and organic matter from washing into waterways, as soil can carry nutrients into the waterway.

Additional Resources

For more on Blue-Green Algae, there are resources available to explore from IDEM partners (ISDH, BOAH, and IDNR) and through the IDEM factsheet entitled Blue-Green Algae (available on the IDEM Fact Sheets page under Watersheds and Nonpoint Source Water Pollution).

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