ST. PAUL — Minnesota needs to go on a low-salt diet.
That’s the advice of the state Pollution Control Agency, which is trying to cut back the amount of salt flowing into the metro area’s lakes and rivers.
“This is getting a lot worse,” said John Stine, director of the nonprofit Freshwater Society, which fights against excessive salt use.
According to the PCA, salt from winter highway maintenance is by far the biggest source of salt pollution, and it is concentrated in the metro area’s waterways. Agency officials say that out of the 53 saltiest lakes and wetlands in the state, all except three are in the metro area.
Of those, the worst salt pollution was in Spring Lake in Spring Lake Park. Others on the top 10 list of saltiest lakes were in Minneapolis, St. Paul, Woodbury and Maplewood.
The saltiest creeks in the metro area are Elm, Shingle, Battle, Bass and Minnehaha.
Sales of road salt nationwide more than doubled from 1991 to 2009 to 22 million tons, according to the national Salt Institute. The PCA said that about 365,000 tons of salt is applied to metro-area roads every year.
To cut back the state’s salt habit, the PCA last week proposed tough new rules.
Some cities would be required to teach businesses and institutions about salt use. In others, developers would be required to install runoff treatment systems whenever they replace more than an acre of pavement.
The Society’s Stine said that salt is a mineral that does not degrade in nature. It persists in lakes until it is flushed out, which can take years. It can be fatal to plants and animals.
“Applying road salt is certainly an important safety practice,” said Stine. “But we need to learn the most efficient ways to use it to achieve the same benefits.”
Stine said that up to 70% of road salt bounces off roads and ends up in ditches.
He said that road-salt use could be minimized by:
- Plowing more often, to prevent ice from forming.
- Applying salt at the right time and temperature.
- Using salt in brine, sprayed as a liquid onto road surfaces.
For the past 19 years, the Freshwater Society has sponsored an annual symposium on road-salt use.
In October, about 300 snowplow drivers, public works officials and business owners attended the 2019 symposium to learn about better ways to apply salt to roadways.
The PCA said that across the state, other large contributors of salt are fertilizers used by farmers and wastewater-treatment plants. Much of the salt from treatment plants comes from water softeners.
For a list of the saltiest rivers, lakes and wetlands, see the PCA’s Statewide Chloride Management Plan online.
The PCA is seeking public reaction to the proposal to reduce salt use, ending Jan. 10.
The PCA will host a webinar about the proposal from 9 a.m. to noon Dec. 11. For details about the proposals, to view the webinar or to submit comments to the PCA, visit pca.state.mn.us.
10 saltiest metro-area lakes
The Minnesota Pollution Control Agency lists the metro-area lakes with the highest measured levels of salt in milligrams per liter, from 2008 to 2017:
1. Spring, Spring Lake Park, 1,881 mg/liter
2. Kasota Pond North, St. Paul, 1,823 mg/liter
3. Loring (South Bay), Minneapolis, 1,273 mg/liter
4. Brownie, Minneapolis, 1,250 mg/liter
5. Kohlman, Maplewood, 1,100 mg/liter
6. Little Johanna, Arden Hills, 1,060 mg/liter
7. Carver, Woodbury, 850 mg/liter
8. Wirth, Golden Valley, 815 mg/liter
9. Parkers, Plymouth, 716 mg/liter
10. Pike, New Brighton, 710 mg/liter
Source: Minnesota Pollution Control Agency