A cleaner Winona?
A sparkling clean Lake Winona.
A sparkling clean Lake Winona.
Is it possible?
Probably not - and it would cost a lot of money just to try, according to a discussion that took place at an Alexandria City Council meeting Monday night.
But that's what the Alexandria Lake Area Sanitary District (ALASD) may be forced to do if the state imposes stricter phosphorus discharge limits on the treatment plant, according to Paul Nelson, ALASD board chair and Bruce Nelson (no relation), ALASD director.
One idea is to pump all the water out of the lake, killing all the rough fish in the process and then installing a carp trap to prevent them from getting in again. (Carp can be destructive to a lake by rooting up aquatic vegetation and stirring up phosphorus, which fuels algae blooms.)
That would cost about $500,000 - the cheapest of all the alternatives but one that comes with no guarantees it would work.
Another option is to change how ALASD disposes treated wastewater by either spray irrigation - a $40 to $50 million expense - or through groundwater injection, which the ALASD estimates would cost $30 to $40 million.
Yet another idea would be to install additional process units at the ALASD plant to the tune of $20 to $30 million.
The numbers, which Paul Nelson repeatedly described as "scary," should give the city and the seven townships that make up the ALASD an idea of what they're up against. "I didn't bring you any good news tonight," he said.
"When you're talking about that kind of money, you have our attention right away," said council member Sara Carlson.
Lake Winona is a shallow lake in southwest Alexandria with an average depth of just 4.5 feet. Since 1977, the ALASD has owned and operated a wastewater treatment plant that discharges to the south end of the lake.
Because of high levels of phosphorous, which trigger algae and weed growth, the lake has been considered impaired for decades.
To find out how ALASD's recent expansion will affect the lake, the MPCA is in the process of developing an action plan called a Total Maximum Daily Load (TMDL). A TMDL is a calculation of the maximum amount of a pollutant, in this case, phosphorous, that a lake can receive while still meeting state water quality standards.
Paul Nelson told the council that the proposed TMDL limits, which were released last week, would result in significant cost increases for ALASD's customers.
When the plant first opened, its phosphorus discharge was 1,000 parts per billion (ppb), Nelson said. After ALASD's expansion a year ago, that level dropped to about 300 ppb.
A draft of the new TMDL calls for the plant to reduce phosphorus to 100 parts per billion and ultimately to 65 ppb. ALASD leaders said the plant couldn't come close to those numbers without a significant upgrade.
Any extra costs would have to be passed on to customers and the eight government entities that contribute to the ALASD - the city of Alexandria, with 42 percent of the budget, and the seven surrounding townships.
Council member Owen Miller asked if this amounted to an unfunded mandate and Bruce Nelson agreed it was.
One of the most frustrating parts of the proposed TMDL, is that there are no guarantees that any plan would bring the phosphorous levels in the lake down that low, said the ALASD officials. "This is not a black and white science," said Paul Nelson.
Another frustration, Bruce Nelson said, is that the models used to determine the TMDL didn't take into account how shallow Lake Winona is or the fact that its carp population has increased.
Even if the combination of phosphorus reductions and aggressive lake management (such as removing carp) succeed, it's likely that Lake Winona will still have a lot of weeds, Bruce Nelson said. This could discourage residents from using the lake for recreation.
The process of setting the TMDL is a lengthy one that will require public meetings and approval from other government entities, Bruce Nelson said.
The options discussed earlier would also take time. Drawing down the lake, for instance, would require approval from the Department of Natural Resources and 75 percent of the abutting landowners would have to go along with it, Bruce Nelson said.
But he added that ALASD must be prepared for the future. "This is an issue that won't go away today, tomorrow or a year from now," he added. "This is something that will continue to play out over the next 20 years."
The council thanked ALASD leaders for providing the update. "We don't like what we've heard but it's good to hear about it," said Mayor Dan Ness. For more council news, see Friday's paper.