"Diamonds are forever," so the saying goes, but swap the gems for "salt pollution" and it's just as true, according to Brooke Asleson of the Minnesota Pollution Control Agency (MPCA).
"Once that chloride is in our water, it's permanent," said Asleson, MPCA's water pollution prevention coordinator. "It's going to stay with that water wherever it goes, and it doesn't break down."
While "forever" is great for diamonds, permanent salt pollution from winter road salt in Minnesota's freshwater systems wreaks havoc on native species. It kills insects, damages fish eggs and hurts aquatic plant life, Asleson said. Locally, Nine Mile Creek is at risk of salt pollution, according to an MPCA map. While some invasive species can handle chloride pollution, Minnesota is a freshwater state and native species can't adapt to salty waters, Asleson said: "If we try to put a bunch of northern pike in the ocean, they cannot survive."
The only way to remove salt pollution is reverse osmosis, which is prohibitively expensive even for wastewater (let alone lakes and rivers), leaves behind a hyper-salty waste sludge and would kill needed microorganisms in lakes and rivers, Asleson added.
"We can't engineer our way out of this problem," she said. "Our only solution for chloride is to reduce it at the source."
To that end, the MPCA is finalizing a state salt management program, which would be the first of its kind in the country. Both the MPCA and local watershed districts, like Riley Purgatory Bluff Creek and Nine Mile Creek, offer guides and classes for professionals and homeowners to learn how to reduce their salt usage. Professionals who take such classes use 40-60% less road salt without reducing safety, Asleson said.
With the first snowfall of the season under our belt, here's what homeowners can do to reduce salt pollution and keep their sidewalks safe:
- Chip, chip, chip away: Preventing compacted ice from bonding to pavement is the best thing you can do, Asleson said. Once compacted ice has formed, "there's really no amount of salt that can solve that problem," Asleson said. Talk to an expert at a hardware store to make sure you're using the right shovel, too − there are many tools for different types of snow and ice.
- Buy simple products: Avoid products that advertise four or five functions and stick to plain road salt. Unfortunately, Minnesota doesn't have labeling laws for road salt, so companies don't have to label every ingredient in their products. Buyers "really cannot rely on what is written on the bag of salt," Asleson explained.
- A little dash'll do you: The optimal amount of salt is four pounds per 1,000 square feet, or around one grain of salt every 3 inches. Adding more won't make ice or snow melt any faster; "if it's not working, it's because it's too cold to work," Asleson said.
- Use the right chemicals: Below 15 degrees, salt (sodium chloride, or NaCl) stops melting ice. Other compounds, like magnesium chloride (MgCl₂) or calcium chloride (CaCl₂) work until -20 degrees, but they also cause more chloride pollution than regular salt, Asleson said.
- Adjust your travel plans: "Our main hurdle is public expectations," Asleson said. Wanting to see bare pavement everywhere all winter, or driving at or above the speed limit after a January freeze, isn't possible while protecting Minnesota's waters.
The Riley Purgatory Bluff Creek Watershed District (RPBCWD) is offering a series of classes for homeowners, public and private road salt applicators, or anyone who manages snow and ice at a business, nonprofit, or place of worship to prepare for Minnesota's snowy season, the district announced in a news release.
Residents should expect salt shortages in the winter of 2019-2020, the release says, and using less salt also prevents pollution from road salt washing into lakes and rivers. The metro area uses around 365,000 tons of salt every winter, the release says.
The classes, all held at 18681 Lake Drive E. in Chanhassen. are:
- A property manager smart salting techniques class from 9 a.m. to 1:30 p.m. on Oct. 17
- Roads training classes from 9 a.m.-2 p.m. on Oct. 23 and 26