LAKE CITY - The little fishing boat launched as usual from Hansen's Harbor for a late-summer excursion on Lake Pepin, the Mississippi River's broad-shouldered bend through the lush bluffs of southeast Minnesota and western Wisconsin. But just beyond the shoreline riprap, a troubling sight came into focus.
Something resembling a giant, fluorescent mat of Astroturf carpeted the waves ahead. The same green gunk coated other swaths of the sailboat-studded lake -- bringing back memories of the 1988 blue-green algae bloom that caused foul-smelling scum and localized fish kills.
A closer look at the oatmeal-like growth, along with calls to the Minnesota and Wisconsin departments of natural resources, quickly allayed fears that blue-green algae was back. The swaths on the lake this summer are a relatively benign type of aquatic plant called duckweed that may have been swept downriver by this summer's heavy rainfall.
While the duckweed diagnosis isn't cause for alarm, its startling appearance should serve as a reminder that Pepin remains an impaired water body whose very existence is at risk. Without sweeping changes upstream to control pollution and soil erosion, potentially toxic blue-green algae blooms easily could occur in the coming years. The lake itself may not even be there for future generations.
Heavy sediment carried mainly by the Minnesota River is filling in Lake Pepin at a frightening rate. According to the state Pollution Control Agency (PCA), the lake's upper portion (near Frontenac) will fill in within 100 years. The lake's lower portion will last about 340 years if current sedimentation rates continue.
Reviving this beautiful but underappreciated big lake won't be easy because of its river/lake nature and because of the extensive watershed that drains into it. But inaction is not an option. The Mississippi is the nation's premier river, and Lake Pepin is a geologic gem worth fighting for. More important, restoring the lake's health will pay dividends upstream and as far downstream as the Gulf of Mexico, where the river's overload of nutrients and pollution has created the notorious "dead zone."
Fortunately, the critical mass of public sentiment and policy initiative that's needed to begin Pepin's restoration seriously is close at hand. Minnesotans need to ensure that the momentum is sustained.
One of the most important and difficult first steps -- determining how much phosphorus (a pollutant) and sediment the lake can handle -- is inching toward completion. These limits will dictate the measures and policies that will clean up the lake. The state PCA has performed or coordinated much of this painstaking research. Its efforts to set site-specific standards for Lake Pepin and the south-metro segment of the Mississippi River are now moving steadily through the long development process.
