MINNEAPOLIS - The Minneapolis Parks and Recreation Board (MPRB) opened its public boat launches Sunday.
Those boat launches on Lake Calhoun, Lake Harriet and Lake Nokomis must also be inspected for aquatic invasive species (AIS).
"The Minneapolis lakes are zebra mussel free as of now," said Alex Dean, AIS program coordinator for MPRB. "We're kind of an island now that we don't have zebra mussels. Minnetonka, Bryant Lake, White Bear Lake--all of those lakes are infested."
Late last month, Minnehaha Creek Watershed District released its findings of a five-year study focused on how zebra mussels are impacting Lake Minnetonka's water quality.
Zebra mussels were first found in Lake Minnetonka in 2010. Since then, the highest populations are in bays on the east side of the lake with moderate levels of algae -- a food source for zebra mussels. The lower populations are in bays that either have very high or very low levels of algae.
For example, Wayzata Bay (moderate algae) has about 200,000 zebra mussels per square meter while Halsted Bay (high algae) has about 28 zebra mussels per square meter. The study found that in Wayzata Bay there has been an increase in water clarity and a decrease in algae and Phosphorus. However, Halsted Bay has seen little change in its water clarity.
"Once you start eliminating kind of the base of the food web, you're going to have kind of cascading effects all the way up to fish communities and other effects as well," said Eric Fieldseth, AIS program manager at Minnehaha Creek Watershed District.
The study also found that zebra mussels could crash in areas with the highest populations. The zebra mussels are filtering out so much food in some of these bays, like Wayzata Bay, that the population could stave themselves and start to crash.
"It's kind of a boom and bust cycle, it's referred to. Usually after that happens their food source rebounds," explained Fieldseth. Zebra mussels then rebound and the cycle starts over.
The long-term effects of zebra mussels on Lake Minnetonka are still unknown but the study's findings could help other Minnesota lakes faced with infestations.
"It's much safer to use this information from a lake right here than it is to use information from a lake in New York state," said Michael McCartney, research professor for the Minnesota Aquatic Invasive Species Research Center at the University of Minnesota.
The study serves a reminder to boaters about the importance of checking boats and watercraft equipment for aquatic invasive species.
According to Dean, a boat was found with zebra mussels attached to it during a launch inspection Sunday morning at Lake Nokomis. That owner was not able to launch and had to first disinfect the boat.
"We don't have a way right now where we can remove zebra mussels from a lake so the only way to do it is preventing them from coming in," Dean said.
To find out information on boat launch hours and inspection hours, check here.