Clean Boats Clean Waters

The impact of Aquatic Invasive Species (AIS)

Aquatic invasive species (AIS) are a major threat to natural and cultural resources, ecosystem services, recreation, and tourism in the Yahara Watershed. AIS disrupt the ecological balance of our lakes; they can decrease water quality and can increase cyanobacterial growth. The impacts of AIS are not only costly to our lake health and ability to enjoy our lakes, but also have an enormous economic impact. Clean Lakes Alliance is committed to establishing measures to protect our lakes and mitigate the threats of AIS. We strive to raise awareness of AIS in our watershed through watercraft inspection, outreach and education, and infrastructure at boat launches. Our goal is for everyone in the watershed to know about aquatic invasive species, how they impact lake health, and how to help prevent their spread.

AIS in the Yahara lakes

There are several different AIS that impact our lakes. Some are present in all five lakes, but others can only be found in one or two. AIS is spread through the transport of water, mud, or other debris and can attach to boats, trailers, and equipment. By learning about AIS, we can stop their spread within the watershed and prevent new AIS from establishing and harming our lakes.

Spiny Water Flea

These organisms have a large negative impact on water clarity. They eat beneficial zooplankton, called Daphnia, which increases algae in the lakes. They also compete with fish and other organisms for resources and disrupt the established food web of the lakes. According to the Wisconsin DNR, spiny water flea are present in all of the Yahara lakes except Lake Wingra. The best thing we can do to manage their impact is to control the amount of phosphorus entering the lakes.

Zebra Mussels

These organisms also disrupt the balance of the lakes. Zebra mussels feed on zooplankton, plants, and other debris, which depletes food for other lake dwellers, like fish. This filter feeding increases water clarity, which seems like a good thing, but can actually lead to increases in toxic cyanobacteria. Zebra mussels can damage water utilities and watercraft and their sharp shells can be dangerous to swimmers. These organisms can survive on watercraft and gear, and their microscopic young can survive in standing water. Zebra mussels are found in all of the Yahara lakes except Lake Wingra.

Aquatic plants

While native aquatic plants are an important part of the lake ecosystem, there are many aquatic invasive plants that threaten the Yahara lakes. Two of the most common are Eurasian watermilfoil and Curly leaf pondweed, which can be found in all five lakes. Aquatic invasive plants do not have any natural controls, like herbivores, in our lakes and can grow into thick mats of vegetation. This can damage the lake ecosystem and water clarity, in addition to getting tangled in watercraft and making swimming unpleasant. New populations can grow from just one small piece of plant material, which makes cleaning plant debris from watercraft critical to preventing new invasions in other bodies of water.

Invasive snails

Invasive snail species pose a risk to our lakes and streams. They can clog water intake pipes and disrupt the existing balance of food webs in the lake by competing with native species. They can also transmit diseases and parasites to fish, waterfowl, and other wildlife. Currently, invasive snails (Chinese mystery snail and Banded mystery snail) are only present in two of the Yahara lakes. With your help, we can keep these species from spreading and prevent additional species from entering the Yahara Watershed.

Other aquatic invasive species

There are many other AIS that are not currently present in the Yahara lakes. Some of these include Quagga mussel, New Zealand mud snail, Hydrilla, Round goby, and Rusty crayfish. Any of these could be a threat in the future, but with cooperation from all lake users, we can prevent these species from entering and harming our lakes.

Preventing the spread of AIS

Luckily, there are actions we can take to prevent the spread of AIS in our lakes. In Wisconsin, there are regulations in place to control AIS, including laws for boaters and anglers. Wisconsin also has a watercraft inspection program, called Clean Boats, Clean Waters, which allows people throughout the state to take a front line defense against the spread of AIS. Through this program, inspectors educate boaters about invasive species, perform boat and trailer checks for AIS, and report new infestations. In 2022, Clean Lakes Alliance plans to partner with the DNR and Dane County in its first year participating in the Clean Boats, Clean Waters program. Keep an eye out for our inspectors at boat landings on Lake Mendota and Lake Monona. As we build capacity for this program, we plan to expand the impact of our inspectors to include more boat landings throughout the watershed.

The economic impact of AIS

Aquatic invasive species have an enormous economic impact on our lakes. They pose a threat to the fishing industry, tourism, and can damage infrastructure, in addition to their negative ecological impact. For example, spiny water flea has greatly impacted water quality in our lakes, which can be mitigated by reducing phosphorus runoff. Researchers at UW-Madison have estimated that the cost of repairing the damage to water quality in Lake Mendota alone would be between $80 million and $163 million.

According to the US Fish and Wildlife Service, zebra and quagga mussels cost the U.S. economy up to $1 billion annually. In the Great Lakes, AIS account for hundreds of billions of dollars in damages that we know of, but a more accurate estimate is likely to be in the trillions. Preventing the spread of AIS is much more economical than controlling the impacts of a future infestation.

What can boaters do to stop AIS?

Boaters and lake users are the first line of defense against AIS. To prevent AIS from spreading in our lakes, carefully inspect boats and equipment. Remember that AIS can hide easily on watercraft, including canoes and kayaks, and some can be difficult to see. By following these prevention steps every time you leave a waterbody, you can do your part to stop invasive species:

1. Clean – Inspect boats and all equipment. Remove plants, animals, and mud. These could be on boats, motors, trailers, or equipment. Never move plants or live fish away from a waterbody. If there is a station available, wash your watercraft with pressurized water.
2. Drain – Drain all water from boats, vehicles, and equipment. This includes live wells and containers holding your catch.
3. Dry – Dry your watercraft and equipment. Store them in a dry place.

You can support our AIS work by becoming a Friend of Clean Lakes or a Lake Partner! As the watercraft inspection season gets closer, there may be opportunities to volunteer with the program. Email caitlin@cleanlakesalliance.org to learn more.