Easy on the salt: Douglas County seeks ways to prevent runoff into lakes but keep roads safe
When Ben Johnson rumbles down a Douglas County road plowing snow and attacking slippery spots with sand and salt, he watches an electronic monitor that helps take the guesswork out of how much of the mixture he's putting on the road.
Salt has long been used to make winter roads less slippery in Minnesota, and remains the most cost-effective substance for melting snow and ice.
But concerns about salt runoff affecting the quality of Minnesota's lakes has had officials looking for ways to reduce its use.
Over the years, Douglas County has been cutting back on the amount of salt/sand used on the roads. One thing that has made that possible is because the snowplows and the sanding trucks are now calibrated before the drivers go out, which sets a limit for how much can be used.
"Our main goal is to always use less," said Douglas County Public Works Director Dave Robley.
There are 50 lakes in Minnesota — all are within the seven-county Twin Cities metro area — that are listed as impaired because of their salt levels.
In Douglas County, Lakes Agnes, Henry and Winona are on the state's impaired water list for their chloride levels, according to the Minnesota Pollution Control Agency.
To help reduce the amount of salt being used on Douglas County Roads, Robley said over the years, they have changed to a salt/sand mixture and most recently, have started using a salt brine. The brine mixture is one pound of calcium chloride (salt) to 5,000 gallons of water.
Maintenance Superintendent Steve Johansen said something new he tried was putting the salt brine on the roads prior to a snowfall. By pre-wetting the pavement, he said the salt/sand mixture can stick to the road better instead of flying off to the side.
In addition, Robley said the county does not have a "clear pavement" policy, but instead will make sure the roads are clear enough so they are safe for motorists. Snowplow drivers will scrape away what they can and make "wheel tracks" for vehicles to get through rather than dumping a bunch of salt.
Robley also said a long-time policy of the county is to only use the salt/sand mixture at intersections, curves and hills.
Why salt is bad
Johansen recently attended a salt symposium in the Twin Cities where he heard from Brooke Asleson, salt prevention program coordinator for the Minnesota Pollution Control Agency.
He learned that salt,when it runs into the lakes, settles on the bottom and can harm snails and mussels. Eventually, he said, it could affect the fish population but that so far, fish in Minnesota lakes have yet to be affected.
The chloride kills the oxygen in the water, which in turns kills off the natural environment, Johansen said.
Robley said the only way to reverse the effects would be to use a reverse osmosis system, which would not be feasible in a body of water as large as a lake.
Both Robley and Johansen noted, however, that it is not just road salt that can impact the lakes, but rather salt runoff from softeners used to treat tap water in homes as well as the salt used on driveways and sidewalks. They both agreed that salt used by snowplow drivers is the least problematic.
Lakeshore owner impressed
Steve Henry, president of the Lake L'Homme Dieu Lake Association, as well as a board member of the Douglas County Lakes Association, visited with Robley and Johansen recently and said he was pleasantly surprised by the efforts of the Public Works office to reduce the amount of salt used on Douglas County roads.
"We use it (salt) in a more modest amount than the state," said Henry.
Henry said the lakes associations do some monitoring of the lakes, although they don't specifically test for chloride, which is a component of salt.
Henry also said he learned that the salt that runs off into lakes is only 20 percent from road salt and 80 percent from softener salt.
Robley said lake associations around the county, as well as the Minnesota Pollution Control Agency, are usually the ones who will conduct the samples of the lakes.
550 road miles
In Douglas County, there are a total of 550 miles of roads maintained by Douglas County Public Works, 400 of which are paved roads that need to be plowed and salt/sanded in the winter months. In a typical winter season, the county can use up to 1,000 tons of the salt/sand mixture. This year, however, Johansen said the county has only used about 30 percent of that.
"It's a good year for our lakes this year," he said.
Johnson, who has been driving a snowplow for 13 winters, said it is rewarding to make the roads as safe as possible for all motorists.
"Sometimes, people think we are in the way, but we're just trying to make it safe. We try to do the best we can," Johnson said. "Over the years, the demand has become greater for cleaner roads faster."