St. Paul, Minn. – For years, doctors have told
people to stick to a low-salt diet.
According to the Minnesota Pollution Control Agency (MPCA), our waters
should follow the same advice.
Winters in Minnesota bring
slippery roads, parking lots and sidewalks as well as the application of de-icing
materials to keep these surfaces safe and ice-free. Road salt, which contains
chloride, is the most commonly used de-icer. Chloride from road salt enters lakes,
streams, and groundwater after snow melts. Once in the water, it becomes a
permanent pollutant and is harmful to fish, insects and plants.
The chloride that enters surface water is
eventually carried downward into the aquifers that provide the state’s drinking
water, and it can even change the taste of tap water. Over the past five years,
the MPCA has assessed the condition of Minnesota’s groundwater as part of the
agency’s overall vision for clean water. Key findings of the Twin Cities Metro
Area chloride project include:
- One-third
of wells across the state showed an increase in chloride concentrations.
- Groundwater
in the Twin Cities metropolitan area is impacted by high chloride
concentrations.
- 27
percent of the metro-area monitoring wells in sand and gravel aquifers had
chloride concentrations that were greater than drinking water guidelines
set by the United States Environmental Protection Area.
The source of the high chloride concentrations in
the Twin Cities and other urbanized areas comes primarily from winter de-icing
chemicals.
“Salt is a real threat to water quality,” said
Brooke Asleson, chloride project manager at the MPCA. “It only takes one teaspoon
of road salt to pollute five gallons of water. If chloride continues to
increase in groundwater, more waters will likely exceed drinking water and
water-quality standards in the future. We are trying to spread the word that
less is more when it comes to applying road salt because at high
concentrations, chloride can harm the fish and plant life in our waters.”
Recently, the MPCA announced the draft
2014 Impaired Waters List. There are a total of 44 chloride impairments in
the seven-county metro area. Thirty-five of those are new to the 2014 list. Many
more waters may also have increasing chloride levels, but are not yet listed
because of a lack of data to support the decision. All of the impairments in
the metro area are being addressed through the Twin Cities Metro Area Chloride
Project. The project also includes a chloride protection plan for all
metro-area surface waters.
The MPCA remains concerned about the need to
provide safe roads and paved areas, while also protecting water resources from
contamination. The agency recommends the following tips for residents and
individuals who are responsible for winter pavement maintenance:
Shovel first. The more snow
and ice you remove manually, the less salt you will have to use and the more
effective it can be. Then, break
up ice with an ice scraper and decide if application of a de-icer or sand is
even necessary to maintain traction.
Slow down. Drive
for winter conditions, and be courteous to slow-moving plows. The slower they
drive, the more salt will stay on the road where it’s needed.
More salt does not mean
more melting. Use less than four pounds of salt per 1,000 square feet (an average
parking space is about 150 square feet). One pound of salt is approximately a
heaping 12-ounce coffee mug. And be patient: salt takes time to work. Applying
more will lead to unnecessary contamination.
15 degrees is too cold
for most salt to work. Most salts stop doing their job when the temperature is below 15 degrees. Instead, use sand for traction in frigid
conditions.
Sweep up extra salt. If salt or sand
is visible on dry pavement, it is no longer doing any work and will be washed
away. The excess can be swept up and
reused for the next snow or disposed of in the trash.
To learn more about the groundwater report, visit
the MPCA’s website.
For more on what you can do to reduce chloride in our waters, or to read more
about MPCA’s role on this issue, visit the agency’s Twin Cities Metro Area Chloride
Project web page.
Broadcast version
Winters in Minnesota
bring ice and snow, and the application of de-icing materials to keep our
pavement safe. But the chloride in road salt enters our surface waters and
groundwater after snow melts. Once in the water, salt becomes a pollutant and
can be toxic to fish, insects and plants.
According to the Minnesota Pollution Control
Agency, one of the best ways to reduce salt use while keeping pavement surfaces
safe is to shovel snow before it becomes packed down and hardened. The more
snow and ice is removed manually, the less salt will be needed, and the more
effective it can be. Once the pavement is dry, the agency recommends sweeping
up any remaining salt to keep it from polluting nearby waterways.
To learn more about using de-icing salt, visit the
M-P-C-A website at www.pca.state.mn.us.
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The mission of the MPCA is to protect and improve the environment and enhance human health.
St. Paul • Brainerd • Detroit Lakes • Duluth • Mankato • Marshall • Rochester • Willmar www.pca.state.mn.us • Toll-free and TDD 800-657-3864
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