Walking across campus on a stormy day, you may forget that rain once sank into the prairie that is now street and sidewalk. You trudge through the rain to your next class while the water rushes along the street into gutters. Inevitably this water will flow into the lake at about the same time you are sloughing your wet coat into the classroom.
Rainwater around campus, which once took years to filter into larger water bodies, now runs to the lakes within minutes. Compacted soil, pavement and rain gutters throughout the campus force water out of its natural cycle. The lake water then fluctuates in temperature, quality and amount based on weather, pollutants and rainfall in the area.
The Dane County Watershed is a massive system, consisting of 37 lakes, 475 miles of streams and 14 miles of the Wisconsin River, supporting ecosystems throughout the Madison area. Years of construction and agricultural erosion have dumped excess contaminants, silt and phosphorus into this watershed, favoring fewer and less desirable species. The system has been suffering for decades from over-fertilization of chemicals such as phosphorus, and agricultural and urban runoff.
Extreme changes in the watershed purge species that cannot survive on limited resources. Experts believe the biggest problem manifests as large blooms of toxic blue-green algae that feed on the excess phosphorus that sticks to eroding farmland.
\This algae is the thistle of the lake, hardly anything eats it,"" said Dick Lathrop, a state Department of Natural Resources lake researcher.
Erosion disturbs the ecosystem further by creating an extreme environment at the lake's bottom. Sandy, rocky and various soil types that lined the lake bottoms 200 years ago now have become nearly two-foot-deep silt deposits. Most fish can't see food when the silt constantly stirs up, Potter said. Most fish, that is, except carp-a bottom-feeder fish introduced to the Wisconsin at the turn of the century.
""We are shunting resources into producing an undesirable fish [that] competes with walleye. This is a dead end to a positive food chain,"" Lathrop said.
Because of this chain of events, Dane County adopted a county-wide erosion control and storm water management ordinance that went into effect last August. This program targets storm-water, agricultural and construction runoff, sewage spills or other isolated contamination sources. Lake Mendota, the first lake in the chain of Dane's agricultural watershed, is the focus.
Stephen Born, professor at the UW-Madison Department of Urban and Regional Planning said common-sense solutions are needed to maintain water quality and aesthetics.
""We have to be intelligent of how we use the land around the lakes and the whole watershed,"" Born said. ""If we build impervious surfaces around the watershed, we lose the scenic resources of watershed and sit in the middle of the lake and look out on sprawl everywhere.\
