Lake Cornelia is Edina's biggest lake and one of the most used. It's the site of the July 4th fireworks. Joggers and walkers use park trails that skirt the cattail-lined shores. And there's a pier where people fish for bluegills, crappie and sunfish.
But Cornelia has other distinctions: The Metropolitan Council gives its northern half a grade of "F" for water quality, and Cornelia made the council's 2005 "Worst Ten Lakes" list. The northern part of the lake also is on the Minnesota Pollution Control Agency's 2008 draft list as an "impaired water" for the federal Environmental Protection Agency (EPA).
In hot weather, green algae coats Cornelia's surface. Most every spring, dead fish float to the top after the ice thaws.
Jeanne Hansen, who lives on the south end of Cornelia, jokes that the lake looks its best when it's frozen.
Thousands of similar lakes dot Twin Cities suburbs. Like Cornelia, many are shallow and take drainage from parking lots, roads and lawns. They host destructive carp that migrate from lake to lake through storm sewers. Their shorelines clog with rotting leaves, and grass clippings and fertilizer run into their waters from street drains. Phosphorus from that debris robs the water of oxygen and can spur algae growth.
It's a recipe for troubled waters -- and a problem with no easy fix.
In fact, some experts question whether a fix is even possible on some of the shallower lakes.
And if it is, who will do it?