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Conducting the Sanitary Survey

Table 5. Stormwater pollutants can impair habitat, human health, local economies, and the quality of surface waters. 30, 74

Pollutant

Sources

Impacts

Sediment

Construction sites; eroding stream banks and lake shores; winter sand and salt application; vehicle/boat washing; agricultural sites; dirt roads; logging activities.

Destruction of plant and fish habitat; transportation of attached oils, nutrients, and other pollutants; increased maintenance costs.

Nutrients (phosphorus, nitrogen)

Fertilizers; malfunctioning septic systems; bird, pet, and livestock waste; vehicle/ boat washing; gray water; decaying grass and leaves; sewer overflows; leaking trash containers; erosion; lawns.

Increased potential for nuisance or toxic algal blooms; increased potential for hypoxia/anoxia (low levels of dissolved oxygen which can kill aquatic organisms).

Hydrocarbons (petroleum)

Vehicle and equipment leaks; emissions; recent paving projects; fuel spills; equipment cleaning; improper fuel storage and disposal; industrial sites.

Toxic at low levels.

Heavy metals

Vehicle brake and tire wear; vehicle/ equipment exhaust; batteries; galvanized metal; paint and wood preservatives; fuels; pesticides; cleaners; industrial processes.

Toxic to aquatic life at low levels; drinking water contamination; persistent and bioaccumulating.

Pathogens

Livestock; bird and pet waste; malfunctioning septic systems; sewer overflows; overboard discharge units.

Risk to human health leading to closure of shellfish areas and swimming areas; drinking water contamination.

Toxic chemicals (pesticides, dioxins, PCBs, etc.)

Spills; illegal discharges and leaks; industrial processes.

Toxic at low levels. Some are persistent, bioaccumulating.

Debris/litter

Improper waste disposal and storage; fishing gear; leaking rubbish containers; cigarette butts; littering.

Potential risk to human and aquatic life.

According to the EPA, stormwater is now the dominant source of water quality impairment in the US, and so it is regulated as a pollution source. Some urban storm drain outfalls contain combined sewer overflows (CSOs) and are considered to be “point” sources of contamination that require a discharge permit. Several Maine communities (“MS4 Communities”) are subject to EPA’s

Stormwater Phase II regulations, and must obtain a general stormwater permit every five years. Require- ments include CSO abatement and making improvements to stormwa- ter systems.30

However, most of the time storm- water enters streams and rivers untreated. The preferred treatment method is to discharge stormwa-

ter to upland vegetated buffers to allow infiltration. Other stormwa- ter treatment techniques include: sand filtration, soil filtration, and transferring stormwater to the local sewage treatment plant. A long- term approach is to minimize the amount of impervious surface in the watershed.

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