In Twin Cities suburbs, all lakes are not created equal

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.

Many residents who live on shallow suburban lakes, even ones dug by developers as storm water collectors, want the Minnesota ideal: clear water and an open shore, just like the big lakes up North.

But unless a lake is fairly deep and protected from storm water, it's almost certainly not going to happen, experts say.

"Minnesotans love their lakes," said Kevin Bigalke, administrator for the Nine Mile Creek Watershed District, which includes Cornelia. "The mindset is that all lakes are equal, and they're not. These shallow lakes function very differently from lakes such as Mille Lacs."

Bob Kojetin, a 50-year Edina resident who is the city's retired parks and recreation director and a member of the Nine Mile District board, said Cornelia hasn't changed much in decades.

"You're never going to get the lakes the way people want them to be," he said. "We can try to work toward clean water standards ... and keep noxious weeds out."

Many metro-area lakes share Cornelia's water quality problems. In 2006, lakes that were on the Met Council's "Worst-Ten List" included George Watch in Lino Lakes, Colby in Woodbury, Loon in Stillwater Township, Cedar Island in Maple Grove, Hazeltine in Chaska, Upper Twin in Crystal and Eagle Point in Lake Elmo.

George Watch also is on the 2008 impaired waters list. It is a typical shallow lake, said Doug Thomas, administrator of the Rice Creek Watershed District in Blaine.

"These shallow lakes are ... impacted by rough fish and curlyleaf pond weed, which grows quickly in the spring, dies in June and releases nutrients that promote the large algae balloons people see," he said. "When phosphorus is released [from fish feeding on the bottom] the water quality becomes murky."

Responsibility for managing small suburban lakes can seem like a committee effort -- it falls on several agencies and local government entities, which at times makes it seem like no one is in charge.

The Department of Natural Resources has jurisdiction over "public waters," which in cities is defined as lakes bigger than 2.5 acres. Watershed districts work with cities on water quality and storm water issues. In Edina, residents whose homes ring lakes often work with the city to maintain those lakes, paying for the service through assessments. And the city manages buffer zones around lakes in parks.

But no single group manages or monitors water quality.

All of which made homeowner David Brown's seemingly simple request to the Edina City Council last month complicated.

Brown, who lives on Arrowhead Lake at the city's western edge, wasn't there to protest the $404.95 he and 35 other homeowners will be assessed for aeration and weed control on the 22-acre lake. He was concerned that the lake was in transition "from a viable lake into a marsh ... a bog and then a swamp."

Brown told the council that cattails and waterlilies are so thick that they threaten wildlife, as well as the health of the lake. He asked for help in overcoming DNR regulations that prevent the cutting of plants that he said "are destroying the lake" and compared the lake to "a commode" that can't flush itself.

The analogy of Arrowhead as a toilet isn't far off, according to an analysis done for the watershed district. Just 7 feet deep at its maximum, the lake has excessive phosphorus from runoff as well as from die-back of curlyleaf pondweed. The lake, which has no outlet, contains bullhead and sunfish and has been stocked with bluegills and large-mouth bass. But the fish sometimes die off in winter kills.

Bigalke calls Cornelia "a tough nut to crack." Phosphorus levels are so high in the lake's north end -- where the fishing pier and city park are -- that sometimes that water is almost devoid of oxygen.

If Cornelia ends up on the EPA's impaired waters list, the state and a partner like the watershed district probably would begin a study in 2012 to plan phosphorus reduction.

Taking control

If Cornelia ever gets cleaned up, the all-volunteer Conservation League of Edina will be partly responsible. The group was started in 2002 by people who were concerned about Edina's lakes. They raised money for much of the equipment that is used to measure Cornelia's water quality.

While curbing phosphorus is a challenge, Bigalke and Jon Moon, chairman of the Conservation League of Edina, agree that ordinary people can make a difference.

Moon sees a hopeful example in Edina's Lake Pamela. In cooperation with the Minnehaha Creek Watershed District, the shallow lake was dredged and three ponds were added to hold storm water before it enters the lake. The work, finished in 2002 at a cost of nearly $760,000, has dramatically improved water quality.

"That lake is crowded with herons," Moon said. "You can see to the bottom of the lake."