AIS Success Story in La Crosse

In 2015, water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes) – two of the most problematic aquatic invasive species (AIS) in the world – were discovered in Lake Onalaska (Pool 7 of the Mississippi River) near Onalaska and in the Vietnam Veterans Pond on the southside of La Crosse. This marked the first and second time either species had been discovered in La Crosse County.

Water hyacinth, native to South America, and water lettuce, believed to be native to South America and possibly Florida, are ornamentals in the aquarium and water garden trades and are primarily spread by humans, both unintentionally and intentionally. Some facts:

• Boaters, anglers and other outdoor enthusiasts can also transport water hyacinth and water lettuce via boats, trailers and equipment.
• Water hyacinth and water lettuce can thrive in freshwater lakes, rivers, ponds and other waterbodies, and can form dense mats of vegetation that can entirely cover the surface of the water, significantly degrading boating, fishing, swimming, paddling and other recreational opportunities.
• They can also reduce biodiversity, degrade water quality and reduce spawning and nesting habitat for fish and wildlife.
• Because of the detrimental effects they can have on the environment, economy and recreation, the Wisconsin Department of Natural Resources classifies both water hyacinth and water lettuce as prohibited species under NR40, Wisconsin’s Invasive Species Rule. As a result, neither species can be transported, transferred, introduced or possessed without a permit.

Understanding the devastating effects that water hyacinth and water lettuce could have on the Driftless Area’s water resources, River Alliance jumped to action. First up: The Vietnam Veterans Pond. After receiving word of “suspicious aquarium-looking plants,” River Alliance staff loaded up their kayaks and waders and headed to the southside of La Crosse. Staff removed every single water hyacinth and water lettuce plant from the Vietnam Veterans Pond, filling 13 30-gallon trash bags in the process!

Next up: Lake Onalaska. After receiving word that a local fisherman found water lettuce, River Alliance staff grabbed their kayaks and hit the water. The fisherman was right. It was in fact water lettuce, and to make matters worse, water hyacinth was also discovered. Over the next few months, River Alliance teamed up with the U.S. Fish and Wildlife Service, Wisconsin Department of Natural Resources, Brice Prairie Conservation Association and the Lake Onalaska Protection and Rehabilitation District, among others, to monitor, map and remove water hyacinth and water lettuce from Lake Onalaska, in addition to their education and coordination efforts.

In October 2015, volunteers were finding and removing thousands of water hyacinth and water lettuce plants per day. By November 2015, that number was down to a dozen plants or less per day, and by mid-December 2015, volunteers weren’t finding either species. Like the Water Hyacinth and Water Lettuce Response in the Vietnam Veterans Pond, the Lake Onalaska Water Hyacinth and Water Lettuce Response appeared to be a huge success. But the million dollar question remained: Did we successfully eradicate water hyacinth and water lettuce from the Vietnam Veterans Pond and Lake Onalaska?

After extensive AIS monitoring this spring, summer and fall, River Alliance is proud to announce that zero water hyacinth and water lettuce has been discovered in the La Crosse area in 2016.

(But just to be on the safe side, we’ll be back on the water in 2017 to make sure they never show up again!)