What to do about salt: Other communities have spent millions to control chloride pollution
Local officials are kicking around ideas about how to save the area lakes and groundwater from chloride contamination, including a possible drinking water softening plant estimated to cost a minimum of $10 million.
Although salt makes roads safer to drive on and improves clothes washing, eventually much of that salt ends up in lakes, rivers and groundwater where experts say it not only imperils plant and animal species but also tourist economies and human health.
"I really think if you stopped the average person on the street, less than 50 percent of them would be aware that there's a problem," said Steve Henry, president of the Douglas County Lakes Association. "We need to all understand that yes, there is a threat. Yes, there is a problem."
Recent meetings in Alexandria have brought together state lawmakers, lake advocates, local elected officials and representatives from utilities and water-softening businesses to discuss ways to address the problem of salt or chloride. Solutions in other places have driven up water bills for customers and could here as well.
The lakes association is asking the state for five things:
• Continue point source implementation grants that could help fund a softening plant.
• Consider limiting water softeners to demand only.
• License stormwater contractors.
• Fund stormwater handling.
• Fund educational programs through existing agencies.
There are several ways salt gets pumped into the environment. The Alexandria Lake Area Sanitary District says its sewage treatment plant sends more than double the allowable level of chloride into Lake Winona, an amount the state allows for now because sewer plants have no way to remove salt. The permitted level is 262 milligrams per liter, but the plant is discharging 650-700 milligrams per liter, said executive director Scott Gilbertson.
"We're not meeting (limits)," he said. "Not even close."
Alexandria's sewer district is hardly alone. The state has identified chloride to be a problem at sewage plants in almost 90 Minnesota communities, mostly in southern and western areas of the state. The state recognizes that sewer plants are incapable of removing salt.
Gilbertson suspects water softeners are the main culprit behind the salt that goes through the treatment plant. There is no good way to remove salt once it arrives at a water treatment plant, so the focus is on preventing salt from entering the plant in the first place.
Meanwhile, area waters are also threatened by salt applied to roads and sidewalks. Melting snow and rains carry it down slopes and eventually into waterways.
The problems created by chloride are many. Exposure to salt has been found to limit the size of young rainbow trout and kill food sources for fish, according to a 2017 Smithsonian article. Hilary Dugan, a freshwater scientist at the University of Wisconsin-Madison, told the magazine that some increasingly salty lakes provide drinking water for towns and cities, create health issues for people on low-sodium diets.
Chloride can also harm the economy through tourism and property values, Rick Relyea, a professor of biological sciences at Rensselaer Polytechnic Institute in New York, told Smithsonian.
"It's not just a biological problem," he said. "It's an aesthetic problem, a tourism problem, an economic problem; it's all of these things."
Water monitoring shows that salt concentrations are increasing in lakes, streams and groundwater across Minnesota, the Minnesota Pollution Control Agency says. The agency found that 39 Twin Cities area lakes have chloride levels too high to protect fish and other aquatic life, and that salt is likely stressing aquatic life in two trout streams near Duluth and in the Cannon River watershed in southern Minnesota.
The issue of excess salt has driven up water bills in other communities, as they add systems that either eliminate or reduce the use of salt.
The city of Morris is building an $18 million system that will use lime to pre-soften the water for city water customers. Once it comes online in April, residents will see their water bills double, and also become restricted in the kinds of water softeners they will be able to use in their homes, said Blaine Hill, Morris' city manager.
About $12 million of that cost will come from state aid, Hill said, including a fund that the Douglas County lakes group wants to see continue.
Those working on the issue say Alexandria might also need to build such a plant, probably through a partnership between the sewage treatment plant and Alexandria Light and Power, which supplies drinking water to 4,100 customers in the city of Alexandria.
"It's a really big animal. It really is," Gilbertson said. "We've done a lot of studies. We've hired consultants that have looked at our situation."
Chlorine contamination will likely require a two-pronged approach, he said. First, a water softening plant using lime might well eliminate the need for home softeners, and the used lime could be applied to farm fields or consigned to a landfill.
Second, those who rely on well water would be encouraged to switch to the latest water softeners that cut salt use by at least 50 percent. Although studies in Morris found that upgrading water softeners wouldn't go far enough to eliminate environmental concerns, other cities contend with different levels of hardness and may find that upgrades will work for them, said Troy Goodnough, sustainability director for the University of Minnesota-Morris.
At one Alexandria meeting, local Culligan managers advocated for rebates to help homeowners buy new softeners.
"I don't think you can get away with eliminating softeners," said Ryan White, general manager of the local Culligan store.