Reducing Stormwater Pollution

Rain, Rain, Go Away — But Not into Casco Bay!

Combined Sewer Overflow on Commercial At in Portland discharges excess

Combined Sewer Overflow on Commercial St. in Portland discharges excess stormwater and the oil, gas, dirt, pet waste, sewage, and other pollutants it has picked up from city streets.

On a rainy day, stormwater picks up oil and gas, dirt, pet waste, sewage, and other pollutants from city streets. Even air pollutants end up in stormwater, scrubbed out of the sky in particulates clinging to raindrops. So much water rushes down the storm drains that line the streets that it may create a vortex.

Many people think that all the water that flows into city storm drains ends up at the sewage treatment plant. Some does. There, filters, poop-eating bacteria, and chlorine do their work on many contaminants before treated wastewater is discharged into the ocean.

But our sewage treatment plants can only handle so much wastewater at a time. Whenever there is a measurable rainfall, much of the rainwater runoff, along with raw sewage and industrial wastewater, is diverted by overflow pipes directly into the ocean. This prevents the sewage treatment plants from being overwhelmed by an underground tidal wave.


So where does this excess water end up?

You guessed it— in Casco Bay. The City of Portland alone contributes about 1.8 billion gallons of this combined runoff and raw sewage to Portland Harbor each year.

Residents are generally surprised to learn that raw sewage still ends up in Casco Bay. The City is accelerating its response to this problem, as evidenced by torn-up streets as the Public Services Department rebuilds the City’s sewage and stormwater transport system, but the process will take many years and many millions of dollars.


What can you do to help?

  • Divert rain water that runs off your roof into rain barrels.
  • Keep water from flowing off your lawn with plantings or rain gardens.
  • Limit the amount of household water you use; that lessens the amount of water entering the system.
  • Organize a community service project to stencil storm drains in your community to remind people what whatever goes down the storm drain goes into Casco Bay. Contact Mary Cerullo at mcerullo [at] cascobay [dot] org to ask for help.
  • Encourage developers and municipalities to plant vegetated median strips, surface parking lots with permeable pavement, increase green space, and incorporate green roofs into their designs.


The Problem with Stormwater

Childhood rhymes teach us that spring rains are cleansing showers that bring May flowers. Unfortunately, heavy rains are not benign. Stormwater runoff is the leading source of water pollution to the nation’s rivers, lakes and coastal waters. It may contain oil, gas, heavy metals, de-icers, pesticides, fine sediments, fertilizers, and bacteria. During Maine’s mud season, stormwater often takes the form of snowmelt, which delivers a toxic shock of winter’s accumulated wastes to coastal waters after the first thaw.


Finding Toxics in Stormwater

Friends of Casco Bay’s research shows that stormwater is not a theoretical threat to the Bay. We sampled 19 sites from Cape Elizabeth to Harpswell, and found many toxic pesticides in our waters, including:

  • 2, 4-D: banned in five countries, this herbicide is toxic to aquatic invertebrates and has the potential to harm birds.
  • Clopyralid: this herbicide has been linked to birth defects in animals.
  • Diazinon: recently banned from being sold to U.S. consumers (but still legal for use), this insecticide has been linked to human reproductive problems and has a high acute aquatic toxicity.
  • Dicamba: found in surface and groundwater throughout the U.S., this herbicide is toxic to fish and zooplankton.
  • MCPP: along with 2, 4-D, this herbicide is in the same family of chemicals as Agent Orange and is highly toxic to bay shrimp.
  • Propiconazole: this fungicide is a possible carcinogen.

Because our advocacy is grounded in science, we worked in conjunction with the Maine Board of Pesticides Control to collected water samples around Casco Bay. Chemicals we found are shown on this map.

Because our advocacy is grounded in science, we worked in conjunction with the Maine Board of Pesticides Control to collected water samples around Casco Bay. Chemicals we found are shown on this map.

Solving the Stormwater Problem

Friends of Casco Bay is taking a comprehensive approach to reducing stormwater pollution.

Monitoring Water Quality

Our Water Quality Monitoring Program is collecting stormwater samples to monitor the problem. We are also developing a first-in-the-nation volunteer stormwater monitoring pilot project. For this pilot project, we are writing a modular Quality Assurance Project Plan (QAPP) to make the data we collect scientifically defendable. The modular QAPP will also be available for organizations across the country, so others can learn from our experience.

BayScaping to Reduce Toxics in Stormwater

We are also working with our community to reduce the pollutants in stormwater. For example, our BayScaping program is spreading a grassroots ethic for ecological lawn care, teaching residents and businesses how to grow green lawns that keep Casco Bay blue.

Stenciling Storm Drains

Our Storm Drain Stenciling project is a hands-on way for volunteers to “take to the streets” and create greater awareness about the need to reduce stormwater pollution. By painting “DO NOT DUMP” messages near storm drains in their neighborhood, community members learn about their connection to Casco Bay and become local advocates for reducing stormwater pollution.

Friends of Casco Bay has a limited supply of storm drain stenciling kits, available to be loaned to groups in communities around Casco Bay. If your school or volunteer group would like to borrow a kit, please contact Mary Cerullo at 207-799-8574 or mcerullo [at] cascobay [dot] org.