Snapshot Day Volunteers Aid in New Discoveries of Aquatic Invasive Species Across the State

Locations of Snapshot Day rendezvous/training sites across Wisconsin

On August 19th, 2023, water lovers of all ages gathered for a one-day statewide aquatic invasive species (AIS) scavenger hunt as a part of the 10th annual AIS Snapshot Day. This event is coordinated by UW Extension in partnership with River Alliance, the Wisconsin Department of Natural Resources (WDNR), and Extension Lakes. Volunteers met at different local rendezvous sites across the state to learn how to identify AIS such as Eurasian watermilfoil, purple loosestrife, and New Zealand mudsnails, and then searched for them in the field at pre-selected locations.  Initially focused on rivers and streams, Snapshot Day has expanded to include lakes and wetlands. Findings from Snapshot Day are uploaded to the statewide water quality database, SWIMS, where they can be used to track the spread of invasive species and develop management plans.

Every year, Snapshot Day provides a vast amount of AIS data to the WDNR to assist in management decisions, and this year was no exception! 145 participants gathered across 22 meeting locations and monitored 131 sites across 102 different waterbodies in Wisconsin. 48 of those waterbodies had no AIS detected. At 83 sites, volunteers located 15 different AIS species, including purple loosestrife, curly-leaf pondweed, Asian clams/freshwater golden clams (Corbicula), and faucet snails. 

Snapshot Day’s community-based science approach maximizes the number of sites being checked across the state, and the free event allows volunteers to learn about their local waters and how to keep them healthy. As one volunteer stated, “I enjoyed the hands on learning approach. It was helpful to have well informed guides and samples of the invasive species to get a close look at. Once we had a good understanding of what to look for, it was fun to go out and collect samples of what we were finding.”

*as of 9/1/2023, data have not been fully finalized in WDNR’s SWIMS database, awaiting Resource of Interest creation and management by DNR. Reported numbers may vary slightly in future.

We would like to extend a HUGE thank you to all of the volunteers, partner organizations, and site leaders who made this event possible.

Enjoy a few photos of our volunteers in action across the state! Don’t see your location or want to add more photos to our collection? Email Rivers Educator, Emily Heald, at

And don’t forget to follow Snapshot Day on Facebook for future updates!