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Why Reduce?

Stormwater runoff is a serious water quality problem.

Rivers, streams, lakes, ponds, and Long Island Sound are affected by excess stormwater runoff.


The impermeable surfaces of modern cities, such as pavement and rooftops, disrupt the natural evaporation and soil absorption of rainfall. Runoff from hard surfaces causes local flooding and accumulates greases, salts, fertilizers, and pesticides that can kill fish and damage shellfish beds and aquatic plants. In Connecticut’s older cities like Bridgeport, New Haven, and Hartford, many stormwater and sewer systems are combined, causing the pipes to fill up quickly when it rains and forcing sewage into Long Island Sound. These discharges lead to beach and shellfish bed closures every year--which is costly for our tourism and shellfishing industries.


The effects of stormwater runoff are harmful to our waterways and the creatures that call them home. 


Reducing impervious surfaces and managing stormwater where it falls can be a challenge in heavily urbanized environments. Separating combined storm-sewer pipes can also be costly and does not address the pollution problems associated with untreated stormwater runoff. 

There is a direct relationship between impervious surface cover and water quality in Long Island Sound and its tributaries. As impervious surface increases, water quality decreases. In Connecticut, we start seeing impairments to rivers when impervious cover exceeds 12% of total cover type. Save the Sound launched the innovative Sound Health Explorer in the summer of 2015. The interactive mapping tool allows visitors see the relationship between impervious cover and bacterial contamination, and to investigate the the health of beaches, bays, and harbors from New York to Rhode Island. Source:

Stormwater runoff doesn’t have to be so destructive.

Green infrastructure--which uses plants and other engineered systems to mimic nature's hydrologic processes--can filter and soak up stormwater where it falls. Green infrastructure, like rain gardens, bioswales, pervious pavement, and green roofs, can help to reduce stormwater runoff, address localized flooding, and eliminate sewage overflows. 


Cities across the US, including Seattle, Baltimore, Philadelphia, and New York City, have embraced green infrastructure as part of their stormwater and sewage overflow reduction plans. While costs vary, implementation expenses can be lower or equal to traditional infrastructure approaches. Additional benefits make it even more attractive: green vegetation can increase property values, provide habitat for birds and pollinators, and mitigate the impacts of urban heat island effect.


Research shows that green infrastructure can effectively reduce stormwater runoff, filter out pollutants, save cities money, and create jobs.


It’s time to take action!


What is stormwater runoff?

Stormwater runoff is rain or snow that melts and flows over the ground, rather than soaking into it. When stormwater flows over rooftops, roads, parking lots, and other impervious surfaces, it picks up harmful pollutants and carries them to our waterbodies untreated. If not managed properly, lawns and agricultural fields also produce a lot of stormwater runoff--carrying fertilizers, pesticides, and other chemicals that harm fish and other aquatic animals. 

Why is it important to reduce runoff?

Stormwater runoff is one of the largest sources of nutrient and bacterial pollution in Long Island Sound and its tributaries.


Excess nitrogen and phosphorous from stormwater runoff encourages the growth of algae and can lead to large algal blooms that compete with other plants and animals for space, sunlight and oxygen. As algal blooms expand, they deplete the amount of oxygen available in the water--a condition known as hypoxia--which makes the water uninhabitable by fish and other aquatic animals. 


Bacteria from stormwater runoff is also a threat to human and ecological health. Contaminated stormwater can damage drinking water supplies as well as make our rivers and harbors unsafe for recreation. Bacteria from stormwater runoff leads to numerous beach closures throughout Long Island Sound every year (visit to learn more). 


Curbing stormwater runoff and managing rain water where it falls is integral to restoring the health of the Sound and the livelihoods of its residents and commercial fishers. 

What is green infrastructure?

Green infrastructure is an approach to managing rain water and stormwater runoff in a way that protects, restores, or mimics the natural water cycle. 


Green infrastructure combines natural and engineered systems (plants as well as pipes, soil, and stone) to slow down the flow of stormwater runoff, filter it, and, where possible, soak up water or infiltrate runoff back into the ground. 


As opposed to gray infrastructure, or centralized conveyance and treatment systems such as sewer pipes and treatment plants that are underground or otherwise out of view, green infrastructure is largely decentralized, within view, and has the added value of bringing green space to highly impervious urban areas, creating habitat for birds and pollinators, and helping to reduce the impacts of the urban heat island effect. Green infrastructure practices such as rain gardens, bioswales, and improved tree pits can be applied at different scales--often more economically than sewer separation, underground storage tanks and treatment plant expansions. 


Visit our "Solutions" page to learn more about different green infrastructure practices--such as green and blue roofs, rain gardens, bioswales, and porous pavement. 

What is a watershed?

A watershed is an area of land where all water that hits that land drains to a common waterway, such as a lake, river, or ocean. 


Imagine a giant bathtub. When you turn on the faucet and splash water around the tub, all of the water that flows from the sides of the tub to the drain is a part of the same watershed. All of the water that spills over onto the floor...and seeps through to your neighbors a part of a separate watershed. 


There are over 2,000 watersheds in the United States alone, and nine major watersheds that feed Long Island Sound. 


Want to know what watershed you live in? Visit the U.S. Environmental Protection Agency's site to "Surf Your Watershed." 

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