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St. Paul, Minn— Tuesday night, after heavy rains and
flooding in west-central Minnesota, the Moose Lake wastewater treatment plant began
discharging untreated sewage into Moosehead Lake and Moose Horn River. Sewage
was still being discharged as of Wednesday evening. The MPCA Duluth Office has
activated a temporary incident command center to monitor the situation and
provide assistance to City of Moose Lake and Pine County. The MPCA estimates 450 gallons per minute
gallons have been released from the wastewater treatment plant.
Discharging untreated or partially-treated sewage can
occasionally be necessary to prevent sewage from backing up into homes or
damaging wastewater infrastructure during emergencies such as extremely heavy
rain events.
The Moose Lake wastewater treatment plant staff are actively
monitoring the lift station pump system’s capacity to determine when they can
stop the overflow and return to treating all the water coming into the plant.
The plant operator notified the state Duty Officer at
approximately 5:30 p.m. Tuesday night that one of its lift stations was releasing
untreated wastewater into Moose Horn Lake. A second call at 8:30 a.m. Wednesday morning disclosed that a second lift
station was discharging to the Moosehead River.
People with concerns about how to protect themselves after
possible exposure to contaminated lake or recreational waters should visit www.mnbeaches.org.
This site offers a variety of precautions and actions people can take after
contact with water possibly contaminated by bacteria from untreated sewage.
More information about minimizing flood-related pollution
and health risks is available on the MPCA’s
website. The page includes
assistance for managing household hazardous materials, preparing heating oil
tanks for flooding, drinking water well contamination and what to do after the
flood.
Sometimes, weather events such as heavy rains and flooding
can overload nearby wastewater collection or treatment systems.
In some places, stormwater and
wastewater share the same system, which means that large volumes of stormwater will
go through the treatment facility.
In other places, water in saturated
ground leaks through aging pipes into the wastewater system. Sump pumps and
tile systems discharging to the wastewater system also contribute to the
problem.
When something goes wrong, or sewage treatment or collection
systems are overloaded, the wastewater must go somewhere. Usually, it either
escapes from the collection system or the system operators need to release it,
untreated or partially treated. This situation is called a sewage overflow.
Sewage overflows are a “safety valve” to keep sewage from
backing up into homes. Municipal wastewater is typically at least 97 percent
water. When excess stormwater is added to the system, the sewage becomes even
more diluted, but can still contain high levels of disease-causing organisms
and harmful chemicals. Sewage overflows should be prevented if at all possible,
but when they do occur they can be managed to minimize potential impacts.
Things such as the volume and strength (concentration) of the sewage overflow
and the volume, flow rate and sensitivity of the water body into which the
sewage is sent are taken into account when determining whether an overflow is
necessary.
Broadcast version
Following Tuesday’s heavy rains, the Moose Lake wastewater
treatment plant began discharging untreated sewage into Moose Horn Lake and the
Moosehead River. Sewage was still being
discharged as of Wednesday evening. An estimated 450 gallons per minute have
been released from the wastewater treatment plant.
Discharging untreated or partially-treated sewage can
occasionally be necessary during emergencies such as extreme rain events, to
prevent sewage from backing up into homes or damaging wastewater
infrastructure.
The Minnesota Pollution Control Agency and Moose Lake
wastewater treatment plant staff are actively monitoring the situation to
determine when the overflow and return to treating all the water coming into
the plant.
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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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