Financial impacts have been significant to Wisconsin’s water utilities (about $4 million based on 1993 figures) and to power plants (approximately $1 million back in 1993). Although some costs have also been incurred by the lock and dam operators on the Mississippi River, these costs have been substantially less than for the raw water users. The environmental costs of the zebra mussel invasion to water resources are more difficult to quantify, and in most cases, are unknown. The long-term costs, however, are likely to be significant. Ecological studies have recently been completed on two inland Wisconsin lakes where zebra mussels first invaded in 1994. The results of these studies should provide more information on the ecological impacts.

In Wood County, according to the press release, Zebra mussel populations, have been found for the first time in the Wisconsin River watershed in June of 2002. Department of Natural Resources fisheries biologists have confirmed that a mussel from Lake Nepco near Port Edwards is indeed one of the voracious filter-feeding mussels native to the Caspian Sea region, and DNR staff has subsequently found more zebra mussels on the Nepco Dam and on bridge abutments, and Rip-Rap along the lake. The discovery is stirring concerns about the potential effect on the Lower Wisconsin River, particularly on endangered and threatened native mussel populations there. It’s also bringing a sharp reminder to boaters to inspect and remove from their trailers and boats any aquatic plants or zebra mussels before they move their boat to another lake. The primary way that zebra mussels have been introduced into new waters is aboard boats coming from an infested water, including in the bilge water, in bait buckets or on the boat or trailer itself. Places to look are spare tire carriers, bunks, and rollers, the BED of the Trailer, and trailer axels.

“The main message people need to get is these things are going to travel inland because people are trailering boats from zebra- mussel infested waters and bringing them to other waters without cleaning them. “If zebra mussels are found in any number in the Wisconsin River, the one boat that probably delivered zebra mussels to Nepco Lake will have probably caused an ecological disaster to the Lower Wisconsin River because of their failure to clean their boat,” say’s the DNR. Lake Nepco is formed by a Dam, with the two mile creek, the four mile creek and the Bloody Run creek, all flowing into it, and flows into the Wisconsin River west of the lake, and its outfall, is upstream from Petenwell Flowage, Castle Rock Flowage, Wisconsin Dells, Lake Wisconsin and the Lower Wisconsin River way. DNR staff has been examining bridge abutments, dams, and other structures along the Wisconsin River west of the dam between Port Edwards and Nekoosa, and Lake Wazeecha upstream of Lake Nepco to look for zebra mussels and gauge the threat they represent. So far, DNR staff have not found any zebra mussels in Lake Wazeecha or on Wisconsin River stretches immediately downstream of Nepco Lake, YET! “They are on the dam at Nepco Lake, so you’d assume that some would have gone downstream into the river system. By finding none, it could mean that the density is so low right now they may be incapable of reproducing,” Endris says. “That still leaves us with the potential of doing something to keep those densities from increasing to the point the zebra mussels can successfully reproduce in the Wisconsin River, which could be devastating in a water shed that is already troubled by pollution. He and other DNR staff are pondering options for responding, including draining Lake Nepco for the winter. Such a drawdown could create conditions that would kill the zebra mussels and prevent damage to the Wisconsin River if it has not already occurred, but would mean a possible fish kill of enormous proportions, home owners along the shore lines could have a shortage of well water also, and Domtar Papers will need another source of water for their paper making process, all of which will have to be looked at. In our talk today, I said I would look very closely along the shore line areas while fishing and my walks along the river and flowage. Zebra mussels’ impacts on particular waters vary, but in general, zebra mussels are a concern because they form dense clusters that attach to hard surfaces, including native mussels, decrease the oxygen that fish and other aquatic species need, and worsen smelly, unsightly algae blooms. In addition, the zebra mussels can clog boat engines and intake pipes for utilities, and their sharp shells can wash up on shore and make walking on the beach hazardous to humans and wildlife. One particular concern with zebra mussels being discovered in the Wisconsin River watershed is the potential effect on native mussels, including the endangered Higgins eye mussel.

“The zebra mussels have already severely depressed the mussel populations in the Mississippi and there are some large, diverse, mussel beds in the Lower Wisconsin that could be in jeopardy, and that includes the federally-endangered Higgins eye and several state endangered and threatened species.” At present, attempts are underway to raise the Higgins eye mussels at the Genoa Hatchery; the Lower Wisconsin River was one area that had been considered as a site for release of the mussels. The presence of large numbers of zebra mussels there would eliminate that location as a potential site, Endris says. Zebra mussels were introduced into the Great Lakes  as stowaways aboard a foreign-going ship. They were first documented in Lake Michigan in 1990. Boaters and anglers can take a number of steps to prevent spreading zebra mussels and other aquatic invasive species to new waters: