check out here DNR WARY OF FLURIDONE TO CLEAR LAKES OF WEEDS
Ron Seely Wisconsin State Journal Jul 22, 2005
Experts with the Department of Natural Resources say research shows the use of a chemical called fluridone to treat weed-choked Madison lakes could cause more problems than it solves.
Some Madison-area residents are so fed up with the thick weeds and algae this summer that they are petitioning the DNR to try fluridone.
The petition drive was prompted by a Wisconsin State Journal column by Susan Lampert Smith about a lake in Michigan that was treated with the chemical. Fluridone cleared up problem weeds in Houghton Lake within six weeks of its use, though some watermilfoil returned and required spot treatment.
Lake residents told Smith the chemical treatment didn’t harm fish or cause an algae bloom as some had predicted.
Mary Lawson, who has lived on Lake Mendota for years, said she started circulating the petition because lake weeds have made life on the lake miserable.
“We used to be able to enjoy the lake most of the summer,” Lawson said. “But over the last ten years it has really started to deteriorate. We get in and pull the weeds and wheelbarrow them out. Last July Fourth we pulled weeds for four hours and the next night a whole new batch blew in. We can’t even invite friends over any more because it smells so bad.”
Lawson said she has probably collected 50 or 60 signatures and hopes to collect a couple hundred. So far, she said, nobody has refused to sign and all agree that something needs done. She said she will probably present the petitions to the Yahara Lakes Association, which she hopes will in turn approach the DNR.
But DNR researchers said fluridone may not be the panacea some are hoping it might be.
Jennifer Hauxwell, a DNR research scientist who specializes in lake vegetation, said she has been studying fluridone for the last 1 1/2 years. She has collected data on fluridone’s use on four Wisconsin lakes as well as on lakes in 28 other states around the country.
Although she said more research is necessary, Hauxwell said initial information shows fluridone to be effective only for two to four years to treat Eurasian watermilfoil, the stringy and pesky weeds that choke Madison lakes. But on all the lakes where fluridone was used, Hauxwell said, the weed returned, sometimes worse than before.
On Potter Lake in Walworth County, where the entire lake was treated with fluridone, Hauxwell said watermilfoil remained in check for four seasons but then returned. Hauxwell said the return of the invasive weed may indicate that even though the poison kills the plant itself, seed bedsremain in the lake silt and those beds eventually produce plants again.
Research also hints at other problems with using fluridone for whole lake treatment, Hauxwell added, especially on eutrophic lakes – lakes such as Mendota and Monona that have high levels of nutrients. On such lakes, Hauxwell said, water clarity eventually decreases after the use of fluridone and native plants are killed along with watermilfoil.
Almost no research is available on how the chemical affects fish, Hauxwell said. Some fish biologists, however, believe the chemical has the potential to alter a fish population because it kills native weeds that small forage fish feed on, and the decreasing numbers of those fish will affect populations of larger game fish such as bass and walleye.
“You’re changing things,” said Hauxwell. “And how sustainable this is in the long run, we just don’t know.”
Jeff Bode, the DNR’s section chief for lakes, said that until the science is more complete, fluridone will probably remain a chemical used for spot treatments in extreme situations rather than whole-lake treatments.
Sue Jones, with the Dane County Lakes and Watershed Commission, said the county manages the lakes under a plan approved in 1992. That plan relies on weed cutting, she said, and on crucial long-term solutions such as controlling runoff into the lakes and limiting the use of nutrients such as phosphorus on farm fields and lawns.
“The use of fluridone has been relatively recent,” Jones said. “And it’s been mostly pushed by the manufacturer. But it’s still experimental.”
Lawson said the weeds have become so bad that it may be time to try something more ambitious and, even, experimental. “I just don’t think this is something that evolved over a long time,” she said of watermilfoil. “It’s an invasive that has taken over.”
Hauxwell said such concern is understandable and shows how much people care for the lakes. “Everybody, including the DNR, is wanting a magic bullet,” Hauxwell said. “This is a tool, but it’s not a silver bullet.”