Winter chills have killed off the algae bloom UW-Madison students can see-and smell-in Lake Mendota each summer, but what would it take to stop vegetation from choking the lake for good?
Researchers at UW-Madison are probing the ways chemical runoff from agricultural and lawn fertilizers flows into lakes, but some scientists say policy-makers are trying to make decisions based on incomplete studies.
\It's a very political process, and unfortunately that seems to be what drives it, rather than science,"" said John Stier, UW-Madison associate professor of horticulture.
Conflict has grown around fertilizers containing phosphorus, which may run off fields and lawns into nearby waterways. In October, the Dane County Lakes and Watershed Commission requested input from experts, including nine UW scientists, and commercial interests on whether to limit phosphorus levels in lawn fertilizer.
The commission drafted an ordinance that Sue Jones, watershed management coordinator, said was ""one step among many"" toward cleaning the county's waters of chemicals and the algae that clogs them in summer.
The ordinance, which will be aired at a hearing Dec. 11, would ban fertilizers with phosphorus on most lawns, but not gardens, lawns in their first growing season or areas a UW soil test shows to be deficient in the chemical.
According to Brian Swingle, executive director of the Wisconsin Landscape Federation, limiting phosphorus fertilizers would hurt businesses without helping the lakes. Representing state horticultural associations, including sod producers, he said they were ""very much afraid of local ordinances popping up all over the place"" to control the chemical.
UW-Madison has voluntarily used less phosphorus in its fertilizer, according to Sally Rowe, an environmental health specialist at UW-Madison.
But Stier said only 5 percent of the fertilizer sold in the state is used on lawns and gardens, and runoff from turf is small compared to agriculture and industrial sources.
Whatever the source of runoff, its path to the lakes is virtually unhindered once it reaches city streets. Pictures of fish accompany signs on sewer drains to warn of the effect dumping chemicals will have on aquatic life. Nevertheless, according to Anne Forbes, chair of Friends of Lake Wingra, ""A lot of people don't realize that these storm sewers on our corners are like a straight pipe, straight into the lake.""
""Everybody lives on a watershed,"" she said.
