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Stormwater Runoff

• Water falls as rain, snow, or ice

• Most water seeps into the ground

• If the ground is saturated, frozen, or has an impermeable surface, water flows as runoff

Point vs. Non-Point Source

Point vs. Non-Point Source

• Point source:– Travels through a conveyance system– Regulated under permit program

• Non-point source:– Runoff that comes from a wide unspecific area– Addressed through voluntary programs

Why is stormwater a problem?

• Human activities cause stormwater to decrease in quality and increase in quantity

• Caused by developed and disturbed land

Where does stormwater go?

• Travels over land• Carried through Municipal Separate Storm

Sewer Systems (MS4)• Discharges into various creeks and streams• Ultimately, the creeks and streams discharge

into a larger body of water, like the Schuylkill River

Where does stormwater go?

• Stormwater flows to storm drains along the street

• Water may carry pollutants with it

• This runoff goes to streams, rivers, lakes, and the oceans untreated

Southeastern PA Watersheds

DARBY CREEK WATERSHED

Conestoga

Stormwater Pollutants

• Sediment• Oil and grease• Heat (thermal pollution) • Nutrients• Bacteria• Trace metals• Toxic chemicals

Sediment Pollution

• Sediment comes from soil erosion and from decomposition of plants and animals

• Sediment makes water cloudy

• Sediment is the most common type of water pollutant

Sediment Pollution Prevention

• Create vegetative buffers along bodies of water

• Minimize the amount of exposed soil

• Use silt fences when disturbing soil

Oil and Grease Pollution

• The EPA estimates that 200 million gallons of oil are improperly disposed of each year

• 1 quart of oil can contaminate 1 million gallons of water

Oil and Grease Pollution Prevention

• Fix vehicles that are leaking fluid

• If you change your own oil, store it in a container and dispose of properly

Septic System Pollution

• The EPA estimates that 25% of homes in the U.S. use septic systems

• Over 4 billions gallons of wastewater per day is dispersed below ground through septic systems

Septic System Pollution Prevention

• Have septic system pumped regularly• Fix a faulty septic system• Fix faulty toilets and leaky faucets to reduce

water going through the system• Don’t overload the septic system (ex: do

several loads of laundry over several days, rather than all in one day)

Lawn Chemical Pollution

• Lawn chemicals are fertilizers, herbicides, and insecticides

• Over-application can cause toxic levels of chemicals and excessive nutrient runoff

Lawn Chemical Pollution Prevention

• Conduct a soil test• Don’t over-fertilize• Use chemicals

according to their instructions

• Landscape with native plants

Thermal Pollution

• Rain or snowmelt running over pavement picks up heat from asphalt and concrete

• Warm runoff raises the temperature of bodies of water

Best Management Practices (BMPs)

Non-Structural BMPs

• Pollution prevention and source control• Street sweeping• Stormwater collection system cleaning and

maintenance• Low-impact development and land-use

planning• Snow and snowmelt management• Public education

Structural BMPs

• Green roofs• High density

residential areas• Grassed/porous

pavement

Hillside Elementary

Rain Gardens

Rain Impoundment Basin

Benefits of Stormwater Management

• Enhanced opportunities for recreation

• Reduced flood damage• Improved drinking

water quality• Navigational benefits• Reduced illness• Enhanced aesthetic

value