Lake Minnetonka Lake Weed Expansion. Is it the Early Ice-Outs or Zebra Mussels?

*The information on this post is based on the observations of experienced divers that have spent the last decade beneath the surface of Lake Minnetonka.*

Over the past decade, the amount of lake weeds within Lake Minnetonka have been continuously increasing, making it harder to enjoy the lake. If you are a lake goer you may have noticed this change. Every year the weeds have been growing faster and more plentiful than the years before, and this can make swimming, fishing, and boating a hassle. Nobody wants to jump off the dock and land in a bed of milfoil, lose their favorite muskie lure to the weeds, or clog the propellers on their boat. But why are the weeds so bad recently?

Some believe that 2016 and 2017’s early ice-outs were the cause of lake weeds growing in such abundance. With this year having the latest ice-out in the past 150 years, some people think the weeds won’t grow as strong as they have in the past. So are recent years early ice-outs to blame for the weed expansion on Lake Minnetonka?

After spending nearly a decade diving beneath the surface of Lake Minnetonka, Premier Lake Harvesting’s very own general manager, Stephen Paulson believes something else. He believes, as many others, that the explosion in the Zebra Mussel population is to blame. When Stephen began diving in the lake nearly a decade ago, the deepest he saw weeds growing was around 10-12 feet. In 2017 he found weeds growing at depths of 16-18 feet. Something as simple as an early ice-out couldn’t have caused this change. Rather, the increase in water clarity due to Millions of Zebra Mussels filtering the lake water has caused the change.

We believe that although the weeds will reach the surface 1-2 weeks later than last year, they will grow in full force when the water gets warm. The effects of the massive Zebra Mussel population will outweigh the effect of this year's late ice-out.

So what’s next?

We will be writing about our observation every week throughout the 2018 summer. Like our Facebook page if you want to stay updated on these Lake Minnetonka trends.

What are Zebra Mussels doing to Lake Minnetonka?

An Overview

It’s no secret that Zebra Mussels have invaded Lake Minnetonka, but what exactly are the effects that these small filter feeders have on the lake? To start, Zebra Mussels are an invasive species from the Eastern Europe and Western Russia area, and because of this, have no natural predators to manage their population. When you add in the fact that they begin reproducing at 2 years old, live up to 5 years, and an individual female can release up to 1 million eggs every single year, this small invasive species becomes a big problem.

How they harm our lakes

With somewhere between 20,000-30,000 Zebra Mussels in one square meter and the ability of an individual mussel to filter up to one liter of water per day, Zebra Mussels have a few major effects on our lakes. The first effect is how they affect fish and other aquatic species. Because they filter so much water, they are effectively taking needed nutrients away from the native species in Lake Minnetonka.

Another impact these little guys are having on the lake is the massive change in where lake weeds can grow. You may think that by filtering all that water, Zebra Mussels would be depriving lake weeds of the nutrients they need to grow. The reality is quite the opposite. Just like land plants, lake plants get their energy from the sunlight that penetrates the water. This is where Zebra Mussels come into play. By filtering so much water, Zebra Mussels are increasing the water clarity and causing sunlight to reach deeper and deeper depths.

Lasting effects

The result? In the last decade, the depth at which weeds on Lake Minnetonka are able to grow has increased from 10-12 feet to 16-18 feet in the past decade. As of right now we cannot fully reverse the effects of the rapidly expanding Zebra Mussels, however, we can stop them from spreading. To learn more about Zebra Mussel and how to stop them from spreading we have attached a few sources for you!

https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=5

https://www.extension.umn.edu/environment/water/features/zebra-mussels-and-you/index.html

https://www.dnr.state.mn.us/invasives/aquaticanimals/zebramussel/index.html

https://www.minnehahacreek.org/project/usgs-zebra-mussel-zequanox-study

2018 Lake Weed Season

Coming off of a long winter and a late start to spring the beginning of the harvesting season is going to start a couple weeks later than usual this year. With Lake Minnetonka still being relatively cold, lake weeds haven't had a chance to begin their summer growth. Even the invasive species like Eurasian Milfoil have yet to reach the surface in a majority of the lake. Although this is nice for now, as Lake Minnetonka gets warmer and the days get longer, the invasive species and all species of lake weed will begin to grow just as rapidly as they have in the past.

But don't worry too much! With our new mechanical harvesters and increased capacity, we are more prepared than ever to fight back against the invasive species overgrowth.

Preparing for the Weeds

During the 2017 season we were operating at full capacity for the majority of the summer. For the 2018 season we have added two brand new Mechanical Harvesters to our ranks which will more than triple our capacity from last season. These harvesters can cut up to 6 feet deep and store massive amounts of weeds. With the addition of off-board motors we can get to and from our drop off points faster than ever, allowing us to spend more time removing those annoying lake weeds and less time traveling. With these harvesters we can do floating weed and beach clean ups, clear boating paths, and transform any residential property into a shoreline to enjoy.

The lake weeds won't stop growing, but we won't stop cutting!