Blue-Green Algae in Spring Lake Outlet Channel 2013 (before Alum Treatment)
When temperatures climb and the summer sun beats down, conditions are ripe for Minnesota lakes to produce algae blooms. Algae blooms are common throughout the summer, with different species appearing from time to time. Many types of algae are an important part of the food chain; however, some can contain toxins.
Abundance of algae types based on time of year (Credit: Water on the Web http://www.waterontheweb.org/under/lakeecology/14_algalsuccession.html)
Cyanobacteria, better known as Blue-Green Algae, can contain toxins (such as microsystin) that are unsafe for humans and pets. Not all Blue-Green Algae contain toxins, but it is best to assume it does. When in doubt, best keep out! It is important to familiarize yourself with Blue-Green algae so you have a better idea when to avoid the water. The Minnesota Pollution Control Agency (MPCA) maintains a webpage (http://www.pca.state.mn.us/index.php/water/water-types-and-programs/surface-water/lakes/blue-green-algae-and-harmful-algal-blooms.html) with helpful information about blue-green algae and harmful algae blooms and shows pictures of Blue-Green Algae. It can take on different forms, but it has been described as looking like green paint, pea-green soup, or having a blue-green color. It can also have an unpleasant odor. Adults are usually offended by the sight and/or smell of algae which keeps them out of the water. However, children and dogs may not be as adverse to the algae so they need to be watched closely when Blue-Green Algae is present.
Blue-Green Algae (Photo Courtesy of RMB Labs)
There have been rare cases of microsystin poisoning even when no Blue-Green Algae was visible. Based on that fact, the Prior Lake-Spring Lake Watershed District (District) can not confirm if Blue-Green Algae is present for liability reasons. The District can try to help determine what type of algae is present by emailing pictures (info@plslwd.org), but they are not experts at algae identification and do not conduct site visits to identify algae types.
Most algae are non-toxic, like this filamentous algae on Buck Lake (Photo courtesy of Steve Beckey)
However, the District recently learned about some user-friendly test kits that may help indicate if the algae are toxic within 45 minutes. According to Steve Heiskary, an MPCA Water Research Scientist, “[the test kit] is a cost-effective alternative to sending samples to an outstate lab (that takes at least a week to get results). It provides an indication of presence, absence, and/or relative magnitude of microcystin. It does not provide precise quantification.” These kits are not 100% accurate and there is still a risk if the test shows no toxin is present. The District does not endorse these kits and has not used them, but if you are interested in purchasing some for your own use, you can find the kits on this website http://www.abraxiskits.com/products/algal-toxins/. Again, when in doubt, best keep out!
The District does not treat algal blooms and there are currently no short-term solutions to fix algal blooms. Once a bloom occurs, the only option is to wait for the weather to change — significant rainfall, wind shifts, or cooler temperatures — to disrupt the algae’s growth. “With the intermittent periods of rain, followed by high temperatures, blue-green algal blooms will be common on many lakes throughout Minnesota for the remainder of this summer,” said Heiskary.
The best long-term solution to decrease occurrences of algae is to reduce the amount of nutrients (especially phosphorus) being added to the lake. The majority of projects that the District funds reduce phosphorus, the main nutrient responsible for algae growth in area lakes. Some ways you can help with this are reduce your use of fertilizer, clean up after your pets, mow your grass clippings into your yard (rather than onto the street or into the lake), rake up your leaves, use rain barrels to catch roof runoff, and install a rain garden or shoreline buffer. The District has incentive programs to help defray the costs of rain barrels and installing rain gardens and shoreline buffers (https://www.plslwd.org/get-involved/cost-share/).
If you believe you or your pets are experiencing adverse health effects (vomiting, diarrhea, coughing, eye irritation) due to contact with, or ingestion of, lake water/algae, seek medical attention immediately. Potential harmful algae blooms should be reported to the MPCA at (651) 757-2419. If you have questions or concerns regarding algae, please contact Jaime Rockney at the Prior Lake-Spring Lake Watershed District: jrockney@plslwd.org or (952) 440-0068.
Other Blue-Green Algae Articles and Information:
Dogs as sentinels: Blue-green algae brings toxic mystery to Minn. waters – MPR
Climate Change and Algal Blooms – EPA
Harmful Algal Blooms Fact Sheet – MDH
Harmful Algal Blooms Photo Gallery