Water quality, flooding propel diversion project
As a resort community that relies on tourism for its economic vitality, Lake Geneva, Wis., was facing a problem. An undersized storm sewer was contributing to frequent street flooding in the city’s central business district and historic neighborhoods. Additionally, discharge from an outfall at Library Park was compromising the beauty of the nearby municipal beach and the quality of the lake that had made the community famous.
An hour’s drive from both Chicago and Milwaukee, Lake Geneva developed in the 1800s as a summer retreat for the wealthy. Today, it remains a popular destination for thousands of people seeking a weekend getaway. “Our permanent population is about 6,700, but our weekend population probably blossoms to 20,000 or 30,000,” says Daniel Winkler, director of public works and utilities for the city. “Lake Geneva is a place for having dinner and shopping. There’s a lot of boating, and we have boat tours and the beach, which are very popular.”
As development has grown around Geneva Lake, so has concern for water quality. The Geneva Lake Environmental Agency (GLEA), which operates as a shared unit of Lake Geneva and the towns and villages of Linn, Walworth, Fontana and Williams Bay, began noticing changes in the mid-1970s. “We noticed high levels of bacteria, sediment and phosphorous at the Library Park outfall after a marsh northwest of the outfall was filled in for an apartment development,” says Ted Peters, director for GLEA. “In subsequent years, we noticed that, after certain storm events, there was an increase in the bacteria levels in water samples taken at the beach.”
The discharge had an aesthetic impact as well. “Geneva Lake is heavily used by boaters, and, as the water churns up, so does the algae,” Winkler explains. “The algae floats over to the beach, and it accumulates on the shore, where we have to rake it on a daily basis.” In 1997, Lake Geneva took action. With the help of Elkhorn, Wis.-based Crispell-Snyder, the city finalized a two-phase plan to remove pollutants from the stormwater and to divert flow from the lake. The city estimates that, together, the measures will reduce outfall discharge to the lake by as much as 74 percent.
The first phase of the project, begun last November, involves construction of a wet-bottom pond and an enhanced dry basin that will remove pollutants in two different sub-basins of the Lake Geneva watershed. The facilities will hold water long enough for contaminants and sediments to settle, and they will help manage peak flows that can lead to flooding.
In phase 2, the city will construct a 5,400-foot storm sewer to divert flow from Geneva Lake to the less-sensitive White River. Running parallel to the lake, the new line will intercept runoff from the problematic undersized sewer, protecting the lake’s water quality and controlling flooding.
While phase 1 of Lake Geneva’s Stormwater Management Plan is essentially complete, phase 2 is still in the planning stages. The city has paid for planning services and construction of the detention ponds using state environmental grants. The remaining improvements will be funded with revenue from Lake Geneva’s downtown tax increment financing district.
The city has budgeted for construction of phase 2 this year. When completed, the project will bring the total cost of Lake Geneva’s improvements to an estimated $1.8 million.
