January 1994
the monthly newsletter for people who live, work or play on the Upper Mississippi River
Metro Plant Will Reduce Phosphorus Discharge By Reggie McLeod
Vol. 2, No. 1
$2
Silver Lining, Cloudy Water By Roger Uicher
For the first time, limits have been set for phosphorus discharges from the Metropolitan Wastewater Treatment Plant. The Metropolitan Waste Control Commission (MWCC), which owns and operates the plant, also agreed to build facilities to reduce phosphorus discharges by 20 to 25 percent. The plant, sometimes called the Pigs Eye Plant, is on the Mississippi River downstream from St. Paul, on Pigs Eye Lake. During the drought summers of 1988 and 1989 residents on the shores of Lake Pepin complained of foul odors and mysterious fish kills. Many suspected that phosphorus discharges from the Metropolitan Wastewater Treatment Plant were to blame.
During the drought summers of 1988 and 1989 residents on the shores of Lake Pepin complained of foul odors and mysterious fish kills. The complaints led to a study that produced a five-inchthick report released early in 1993 (see Big River, May 1993). The report described complex scenarios including other sources of phosphorus, especially from fertilizers and manure washed by rains from agricultural land into the Minnesota River, which flows into the Mississippi at St. Paul. Although the study found that the Metro Plant accounted for about 25 percent of the phosphorus entering
(Phosphorus continued on page 4)
Your average river's got the flow, the fish, the flights of water birds. You don't expect a forest in the floodplain, but the Upper Mississippi seems as much woods as water. Islands, unnamed isthmuses and mini-mountains like Trempealeau grow a number of species, but these days the predominant bottomland hardwood is silver maple. "Acer saccharinum Linnaeus " sounds sweet, but not as sweet as A. "saccharum," the true sugar maple of the uplands. It can be tapped but you'll have to boil more sap for real syrup. Silver's are full of water. A mature specimen 75 feet high with a crown 75 feet wide will suck up a ton of water per day. A big river valley is prime habitat.
A mature specimen 75 feet high with a crown 75 feet wide will suck up a ton of water per day. Somebody said, "Nature abhors a vacuum." Forester Randy Urich says ecological changes in the last century have favored a sub-climax species like silver maple. He surveys the bottomlands from St. Paul to Guttenberg, Iowa, for the Army Corps of Engineers. "Pioneer" species such as willow and cottonwood thrived in the new light and wetlands created by the lock-and-dam system. In the shadows of that overstory, shade-tolerant silver maples slowly
(Silvers continued on page 2)