Soil expert: Banning phosphorous may not help Geneva Lake
(Published Wednesday, February 28, 2007 11:15:32 AM CST)
A d v e r t i s e m e n t
By Chris Schultz Gazette staff
LAKE GENEVA-Not everyone is convinced a ban on urban phosphorus fertilizer will help keep lakes clear of excessive algae and lake weeds.
Dr. Wayne Kussow, now a retired professor of soil science at UW-Madison, doesn't believe lawns leach significant amounts of phosphorus into storm water runoff.
"I don't feel the research is out there for a ban for environmental purposes," Kussow said recently in a telephone interview.
Minnesota, New York, Michigan and California have statewide control of phosphorus fertilizer, he said.
"These are political decisions," Kussow said.
But he also doesn't believe a "ban" on phosphorus is harmful, as long as the law allows phosphorus applications on lands that are poor in the nutrient.
The Geneva Lake Environmental Agency is developing a proposed ordinance to ban the sale of phosphorus fertilizers in the lake watershed.
Lake Geneva, Fontana, Williams Bay, Walworth and the town of Linn would have to approve the ordinance for it to have any effect, said Ted Peters, environmental agency director.
The ordinance proposed by the environmental agency is based on a countywide ban recently passed by Dane County. The town of Delavan and city of Delavan recently approved phosphorus bans also based on the Dane County law.
Kussow was one of several experts to testify in connection with the Dane County ordinance.
A synopsis of the testimony showed disagreement over how much phosphorus gets into the lakes from urban lawns. Kussow said no more than 6 percent of phosphorus runoff countywide is from urban lawns, while another expert, Steve Carpenter, a UW-Madison limnologist, said the figure is more like 19 percent.
In a telephone interview, Kussow said his studies show that only 1 percent of the phosphorus in Lake Mendota is from lawn fertilizer, while 80 percent is associated with snowmelt, with the primary source being decaying vegetation.
Unless a lake's phosphorus load is reduced 20 percent, the vegetation doesn't change much. Banning urban use of phosphorus fertilizer won't come near that level of reduction, he said.
Peters said he's familiar with Kussow's work and respects the research.
If Kussow's statement that 80 percent of phosphorus runoff comes from decaying vegetation is true, however, that phosphorus got into the vegetation somehow, he said.
"I know that Dane County is very satisfied with their ordinance," Peters said.
He said he plans to have a proposed phosphorus ban ready for the Lake Geneva City Council by next month.
