Minnesota cities look to reduce chloride from water plants

March 16, 2019
1 of 4
In a Feb. 28, 2019 photo, The Pomme de Terre River flows through the city of Morris, Minn. The city's wastewater treatment plant is discharging too much chloride into the river, largely due to water softeners. (Kirsti Marohn/Minnesota Public Radio via AP)

MORRIS, Minn. (AP) — Some Minnesota cities are grappling with how to reduce the amount of chloride being released from their wastewater treatment plants into lakes and streams, threatening aquatic life.

The state estimates that about 100 municipal wastewater treatment plants are releasing more chloride than allowed by state standards.

While road salts are the biggest culprit of excess salt entering the environment, researchers at the University of Minnesota’s Water Resources Center are telling cities to address the use of water softeners. Homes and businesses connected to municipal sewer systems send chloride from the water softeners down the drain, which ends up at the wastewater plant.

“For a lot of these wastewater treatment plants, road salt isn’t going to be their No. 1 source,” said Sara Heger, the center’s research engineer. “If they are looking to reduce their effluent limit to an acceptable level that will let aquatic species thrive in that water, they’re going to have to deal with water softeners.”

Many residents have in-home water softeners, which remove minerals such as calcium and magnesium. Hard water can leave hair feeling dry and spots on dishes, while mineral deposits in pipes and water heaters can cause damage, Minnesota Public Radio reported.

Heger said there isn’t an “easy fix” to remove chloride from water, which is often a difficult and expensive process. Most water treatment plants weren’t designed to remove chloride.

The city of Morris plans to open a new $18 million plant this spring, which will use lime and soda ash to centrally soften water before it’s piped into homes and businesses. Morris is getting $12 million in state aid to help pay for the plant, but residents will likely be charged higher water rates to cover costs.

Morris officials also plan to adopt an ordinance that requires residents to switch to an on-demand water softener model if they continue to use water softener.

Brooke Asleson, a water pollution prevention specialist with the Minnesota Pollution Control Agency, said an on-demand model only softens water and recharges when needed instead of automatically every several hours. They reduce the amount of chloride released by up to 60 percent, compared to the older models operating on a timer, Asleson said.

Many have recommended creating a financial incentive for Minnesota residents to reduce their softener salt use. Gov. Tim Walz’s budget proposal has outlined funding for communities to offer grants to homeowners who eliminate their softener or upgrade to an on-demand model.


Information from: Minnesota Public Radio News, http://www.mprnews.org

All contents © copyright 2019 The Associated Press. All rights reserved.