Algae information


Algae: what causes it.

From Minnesota Waters:

The main reason some lakes are green is due to phosphorus and fertilizer.

Phosphorus is a necessary and natural elment found is soils, and rocks. An essential nutrient for animals and plants, it is also a common nutrient in fertilizers. However, the phosphorus that makes your lawn and garden green can also make the lake green. Of all elements, phosphorus is the key to managing lakes as “clean not green”. One pound of phosphorus can produce 500 pounds of algae. Keeping phosphorus out of the lake is one of the most important things that we can do to protect water quality.

Here are a few simple ways you can help reduce phosphorus inputs to your lake:

Properly operate and maintain septic systems, pump at least every 3 years.

Immediately repair or replace non-complying septic systems.

Develop and maintain a shoreline vegetation buffer.

Use zero-phosphorus lawn fertilizer or don’t use any.

Limit the use of pesticides and other garden chemicals.

Keep bonfires away from the lake, and clean up all ash.

Use phosphorus free dishwasher detergents.

Clean up pet waste.

Cover loose soil areas with vegetation and remedy any shorline erosion problems


link to Algae information.

MPCA link to algae and toxic algae.


From The algal blooms look like green, blue-green, white or brown foam, scum or mats floating on the water. Recreational exposure to toxic blue-green algae can cause eye irritation, allergic skin rash, mouth ulcer, vomiting, diarrhea, and cold and flu-like symptoms. . 

It can be fatal to pets.

Below is the process for reporting Blue Green Algae that could be toxic. Not all Blue Green Algae is toxic, it has to reach a threshold that causes toxicity but it is better to be safe then sorry.
  • Look for dead birds, squirrels and rabbits or other small animals in the area of an algal bloom. Report what you have found.
  • Report any illnesses affecting people and pets
  • Stay out of the water, keep pets away from the water. Shower immediately after swimming if you entered the water.
  • Get Medical attention for humans and pets that are possibly ill from Blue Green Algae
Contact either Community Health (Matt Finkenbiner at 507-357-8231) or Environmental Services at 507-357-8540) and we can contact the proper MPCA staff person for your watershed.   If you contact the MPCA directly they will contact us.  We will then work together on getting the area posted. Another option is the State Conservation Duty Officer at DNR Information Center: 1-888-646-6367 or Local # 651-296-6157 or during non business hours call the STATE PATROL DISPATCH RADIO TELEPHONE NUMBER at Mankato (507) 389-1172 and request the conservation duty officer to return your call.

To minimize risks from harmful agal blooms:
  • Avoid body contact with blue-green algal blooms.  This includes swimming, wading, water-skiing.
  • Children especially should avoid contact.  Their small body weight means their exposures to blue green algae will be higher than adults, given the same volume of water intake.
  • Local health and environmental agencies are encouraged to and generally do post recreational areas with signs and brochures to inform the public of the presence of blue-green algae blooms. 


Thank you.

Le Sueur County Environmental Services

 507-357-8540 (Metro line)
507-357-8541 (Fax)

Please let me know if you have any questions.  The following website may provide you additional info as well:

Katie Brosch (MSU-WRC) – 507.389.2704 (

Joe Pallardy (MSU-WRC) – 507-389-5492 (

Shaina Keseley (MPCA) – 507-206-2622 (