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Improving Stormwater Management at Residential Sites
By Steve Tonn, Extension Educator - Omaha Metro Area Lakes

Stormwater is water from irrigation, rain or melting snow that does not soak into the ground. It flows from rooftops, over paved areas and bare soil, and across sloped lawns. As it flows, this runoff can collect and transport soil, pet waste, salt, pesticides, fertilizer, oil and grease, leaves, litter and other potential pollutants. A heavy rainstorm isn’t needed to send pollutants rushing toward an Omaha metro stream or lake. A garden hose or misdirected lawn sprinkler can supply enough water.

Constructed stormwater drains and sewers convey runoff from your property to a nearby stream or lake. Contrary to popular belief, storm sewers do not carry stormwater to wastewater treatment plants.

Polluted stormwater degrades our lakes, streams and rivers. Soil clouds water and degrades habitat for fish and water plants. Nutrients such as phosphorus promote the growth of algae, which crowds out other aquatic life. Toxic chemicals such as antifreeze and oil from leaking cars, carelessly applied pesticides and zinc from galvanized metal gutters and downspouts threaten the health of fish and other aquatic life. Bacteria and parasites from pet waste can make nearby lakes and streams unsafe for recreational uses.

Across the country, public officials are turning their pollution control efforts from wastewater discharges to stormwater management in urban and rural areas. Stormwater pollution cannot be treated in the same way as water pollution from discharge pipes, because it comes from many different sources. Contaminants are carried by stormwater from every street, parking lot, sidewalk, driveway, yard, garden, and any open area. The problem can be solved only with everyone’s help.

Oil stains on your driveway and outdoor spills of antifreeze, brake fluid, and other automotive fluids are easily carried away by a rainstorm or by hosing off the driveway. An oily sheen on runoff from your driveway is a sure sign that you need to be more careful. Pans, carpet scraps and matting can catch drips. Routine maintenance can prevent your car from leaking and help identify leaks. If you change your own oil, be careful to avoid spills and collect waste oil for recycling. Oily car parts and fluid containers should be stored where rain and runoff cannot reach them. Never dump used oil, antifreeze, or gasoline down a storm drain, in a ditch, or on the ground. These wastes will end up in a nearby lake or stream.

Washing your car in the driveway creates runoff without the help of a rainstorm—your hose provides the water. The dirty, soapy runoff drains directly into storm sewers, carrying oil and other pollutants as it goes. Try washing your car on the lawn or, better yet, take it to a commercial car wash that sends its dirty water to a wastewater treatment plant.

Droppings from dogs and cats and from other commonly kept animals like exotic birds, rabbits and hand pets can be troublesome in two ways. First, pet wastes contain nutrients that can promote the growth of algae if they enter streams and lakes. Second, animal droppings can be a source of disease. The risk of stormwater contamination increases if pet wastes are left on sidewalks, streets, or driveways where runoff can carry them to storm sewers or surface water. Droppings that are not mixed with litter or other materials should be flushed down the toilet. Or, if local laws allow it, droppings may either be buried or wrapped and put in the garbage for disposal.

If left on sidewalks, driveways, or roads, grass clippings and other yard wastes will wash away with the next storm. Although leaves and other plant debris accumulate naturally in streams and lakes, homeowners can contribute excess amounts of plant matter, especially in areas with many homes. This can lead to water that is unattractive or green with algae and unsuitable for recreation. Bacterial degradation of these organic wastes can significantly reduce oxygen levels in shallow waters during summer months, leading to fish kills. Avoiding the problem is easy—sweep clippings back onto the grass, and compost leaves and garden wastes on your property to recycle nutrients.

Areas of bare soil often exist in vegetable and flower gardens, on newly seeded lawns and around construction projects. Even on gentle slopes, water from rain and snow can remove large amounts of soil and carry it to streams and lakes. Planting grass or other ground covers is the best way to stop erosion. Putting straw or chip mulch over gardens and newly seeded areas will slow erosion. Straw bales, diversion ditches and commercially available silt fences around construction sites can help slow runoff and trap sediment on-site. If you are working with a contractor, insist that precautions are taken to control runoff and erosion during construction.

Concrete and asphalt roads, driveways, and walkways prevent rainwater from soaking into the ground. When you have the choice, consider alternative materials such as gravel or wood chips for walkways. Avoid paving areas such as patios. Where you need a more solid surface, consider using a “porous pavement” made from interlocking concrete blocks/pavers or rubber mats that allow spaces for rainwater to seep into the ground. If an area must be paved, keep it as small as possible.

Your house roof, like pavement, sheds water. If downspouts from roof gutters empty onto grassy areas, the water will have a chance to soak into the ground. Aim downspouts away from foundations and paved surfaces. For roofs without gutters, plant grass, spread mulch, or use gravel under the drip line to prevent soil erosion and increase the soil’s capacity to absorb water. Consider using cisterns or rain barrels to catch rainwater for watering lawns and gardens in dry weather.

Residents are personally responsible for contributing some of the pollutants that run off their property. Runoff pollution is the major cause of water quality in urban watersheds. The actions done around our homes add up to pose a threat to the Omaha metro lakes and streams. Too be truly effective, runoff pollution prevention must a collective act, just as pollution is a result of our collective actions.