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Our efforts to stem stormwater pollution
CBEP and our partners work
through a
range of initiatives to minimize pollution loading from
stormwater. Our efforts include catalyzing
regional stormwater management, promoting low-impact development
techniques, educating the public about stormwater pollution, and
supporting subwatershed management planning. Learn more about our
stormwater work:
The
water that flows along the ground after a rainfall, or
during snowmelt, is known as stormwater. As it crosses roofs, roads,
and parking lots, stormwater picks up
pollutants like oil, pesticides, bacteria, sediments, and heavy
metals. Those pollutants are then washed into the storm sewers
and streams that eventually drain into Casco Bay. Polluted runoff
can degrade water quality in the Bay, impair fish and wildlife habitat,
and reduce biological diversity.
In the Casco Bay watershed, most contaminants in stormwater come from nonpoint sources,
such as oil leaking from cars, fertilizers and pesticides washing off
lawns, failing septic systems, and fuel spills from recreational
boats. Such seemingly small sources add up to significant water
quality problems in urban streams throughout the watershed.
Impervious surfaces
In
developed parts of the watershed, impervious surfaces such as roads,
parking lots, rooftops, and compacted soils increase the volume of
stormwater runoff by preventing rain water from seeping into the
soil. Instead, those surfaces direct pollutant-laden runoff into
stormwater drainage systems, which empty into Casco Bay. High
stormwater volumes can also increase flooding, erode stream channels,
and reduce groundwater recharge.
Combined Sewer Overflows (CSOs)
When
a community's sanitary waste and stormwater runoff flow in the same
underground pipes, the system is called a combined sewer. During
heavy rainfall, stormwater can overwhelm the capacity of such sewers or
of sewage treatment plants, causing discharge of untreated sewage mixed
with stormwater into Casco Bay waters. Those discharges are
called combined sewer overflows (CSOs), and they result in the
introduction of millions of gallons of polluted water to rivers and the
Bay annually. Pathogens from CSOs can lead to human health
threats and the closings of beaches and shellfish beds.
Click here
or on the Current Projects button to the right for
examples of the stormwater activities that CBEP and our partner
organizations are supporting.