Mirror Lake: Recreational Water Advisory
September 18, 2019
The recreational water advisory for Mirror Lake is still in effect. Based on a sample from September 9, there are still high numbers of blue-green algae in Mirror Lake. The numbers continue to exceed the World Health Organization (WHO) threshold for moderate risk of adverse health impacts from algal toxins (see graph). The numbers have come down slightly from August 19th. The public should continue to have no contact with the water in Mirror Lake. This includes keeping pets out of the water.
August 28, 2019
The public is advised to have no contact with the water in Mirror Lake.
The Nine Mile Creek Watershed District (NMCWD) has confirmed that there are high numbers of blue-green algae in Mirror Lake. High levels of blue-green algae are a concern because this type of algae can produce algal toxins, which can pose a health threat for pets and people when concentrations become high enough. The NMCWD is urging residents to stay out of the water and keep pets away from the water, as well.
An August 19 water sample that the NMCWD took from Mirror Lake indicated blue-green algae numbers that exceeded the World Health Organization (WHO) threshold for moderate risk of adverse health impacts from algal toxins (see graph). It is recommended that people and pets stay out of the water until the blue-green numbers decline to within the low or no risk of public health effects categories.
The NMCWD will collect another sample from Mirror Lake in the next few weeks. The NMCWD will release updated information on algal levels when it is available following the sampling event.
For more information on blue-green algae and harmful algal blooms visit:
FREQUENTLY ASKED QUESTIONS
WHAT ARE BLUE-GREEN ALGAE BLOOMS AND CYANOTOXINS?
Blue-green algae are a type of cyanobacteria present at low levels in many Minnesota lakes and ponds. When water is stagnant, warm and rich in nutrients – especially phosphorus – cyanobacteria can grow quickly, forming “blooms.” These blooms typically look like pea soup or bright green paint. These blooms can last several weeks or longer and and are considered harmful (harmful algal blooms or HABs) since they are capable of producing toxins, called cyanotoxins, which can harm humans and animals.
WHAT ARE THE HEALTH EFFECTS FROM CYANOTOXINS?
Blue-green algae and cyanotoxins have been shown to cause acute inflammatory effects or illnesses. Exposure to blue-green algae while in recreational waters may cause skin irritations, including rashes, hives, swelling or skin blisters. Ingestion of cyanotoxins can also cause more severe health effects such as liver or kidney damage, depending on the cyanotoxin and the magnitude, duration and frequency of the exposure. Health effects from cyanotoxin exposure in pets, wildlife, and livestock can include vomiting, diarrhea, seizures, and death.
HOW DOES CYANOTOXIN EXPOSURE OCCUR?
Exposure to blue-green algae and their toxins may occur by accidental ingestion or inhalation of toxin-contaminated water, or skin contact during recreational activities (for example, swimming, waterskiing, or tubing). Animals such as pets, livestock, and wildlife may also be exposed to cyanotoxins if they drink water from toxin-contaminated water bodies, lick their fur after swimming in such waters, or consume toxin-containing algal scum or mats.
IS ANY BLUE-GREEN ALGAE BLOOM POTENTIALLY DANGEROUS?
Yes. Any blue-green algae bloom may potentially cause harm, and it is difficult to tell by looking at a bloom if it is producing toxins. To determine if the bloom is producing toxins, it needs to be tested by trained personnel.
WHAT TYPES OF ALGAE ARE ASSOCIATED WITH TOXINS?
Blue-green algae are photosynthetic bacteria that are capable of producing toxins.