LPLA:The Facts

The Facts

Lake Pepin is at the downstream endpoint of the most polluted reach of the Mississippi River in the state. It is no accident that this reach begins at the confluence with the Minnesota River. The Minnesota supplies most of the sediment that makes the Mississippi constantly muddied, and threatens to fill upper Lake Pepin with mud before the present century is past. Suspended solids from the Minnesota River make the Mississippi incapable of supporting the rich rooted vegetation that once made the river and Lake Pepin a haven for ducks and swans.

Nuisance algae blooms during hot, dry summers are another threat to water quality in Lake Pepin. Metropolitan wastewater treatment facilities have drastically reduced their phosphorus discharges, the result of a successful campaign to protect Lake Pepin following disastrous algae blooms in 1988. However, demographers expect an additional million people to settle in the Twin Cities over the next couple of decades, a trend which threatens to reverse recent progress in wastewater quality. Moreover, continuing high phosphorus loads from the Minnesota River pose an ongoing threat to Lake Pepin. Phosphorus concentrations are so high in the Mississippi, at 150 to 200 parts per billion, that a warm, calm dry spell in any summer could quickly trigger unsightly algae blooms.

The Minnesota Pollution Control Agency will soon complete a Total Maximum Daily Load (TMDL) study that will prescribe reduced loads of sediment and phosphorus from upstream sources, particularly the Minnesota River and Metropolitan Area wastewater treatment facilities. While the MPCA has regulatory authority over wastewater discharge, agriculture, the source of much phosphorus and sediment in the Minnesota River, is largely unregulated.

Make no mistake. Unless Minnesota River sources of sediment and phosphorus are significantly reduced, no efforts by cities in the metro area or elsewhere will make much difference to the health of the Mississippi River and Lake Pepin. What is needed is political will to ensure that significant reductions are achieved - starting with better enforcement of existing land-use authorities, and development of more effective land use policies.