Stormwater Runoff

Stormwater runoff is unfiltered overland water flow that occurs when precipitation on snowmelt flows over the ground, especially over impervious surfaces – which include roads, parking lots, driveways, and roofs. This website page will help you understand the impacts that stormwater runoff has on all of us. But first, it's important to know how the water cycle works.

How does the water cycle work?

The water cycle is the basic process by which water is recycled. When water falls from the clouds as rain, snow, sleet or hail (precipitation) it takes on of the following paths:

·It seeps into the ground surface and becomes part of the groundwater, which feeds streams, wetlands, and aquifers

·It is absorbed by vegetation and then transpires (evaporated from the plant tissues)

·It flows into rivers, lakes, reservoirs, etc.

·It remains in lakes or top soil and eventually evaporates back into the atmosphere

WHAT'S THE PROBLEM?

In a natural setting, the majority of rainfall soaks into the forests and meadows and slowly flows underground, being naturally filtered before reaching streams, lakes, underground aquifers, and Puget Sound. When meadows and forested land is replaced by impervious surfaces (streets, driveways, rooftops, patios, etc.), stormwater runoff is produced. The natural process of the water cycle is modified and the rain water can no longer penetrate into the earth. As a result, the rain water (stormwater) flows directly into storm drains, ditches, and streams, all without the benefit of the natural filtration process.

To add to this problem, stormwater runoff from the urban areas often picks up pollutants along the way – carrying motor oils, fertilizers, pesticides, and even pet waste. These examples represent types of pollution called non-point source pollution. Non-point source pollution is a major problem, and is the primary contributing factor to water quality degradation nation-wide. Regionally, non-point source pollution accounts for over half of the pollution reaching our creeks, streams, rivers, and the Puget Sound.

Tips On What You Can Do

If you burn fuel to heat your home, use a car, truck, bus, boat, train, or airplane, or buy products transported by any of these, you contribute to non-point source pollution. Although one person's contribution to non-point source pollution may seem insignificant, the combined effects of all DuPont residents can greatly influence water quality and quantity in our lakes, streams, wetlands, and the Puget Sound. We must work together to control non-point source pollution and strive to protect our valuable resources.

Here are some handy tips and steps that you can take to reduce non-point source pollution, reduce stormwater runoff, and make DuPont a better place to live.

Pick up after your pets
Pet waste may contain harmful bacteria and organisms (E.coli, salmonella, roundworms, etc.) that spread diseases easily. When pet waste is left on the ground, people and animals can become exposed to these diseases, which are unsafe and can cause illness. To keep our neighborhoods clean and healthy, clean up after your pets; use a plastic bag, seal it, and dispose of it in an appropriate garbage receptacle.

Use pesticides and fertilizers sparingly
When too much fertilizer is used, or it is applied at the wrong time, the excess fertilizer can run off your garden and lawn and ultimately enter into nearby storm drains. If properly used, pesticides can help kill disease causing organisms, control insect pests, and eliminate weeds. If misused, however, pesticides can be harmful to humans, animals, and the environment.

Tips on pesticides and fertilizers

·Use only when necessary

·Do not use before a rain storm

·Spray or disperse on cool, windless days

·Follow instructions on the container

·Do not use products that are both "weed and feed", if you are trying to treat for one specific need

·Avoid spraying pesticides or fertilizers near ditches, lakes, or wetlands

·Dispose of lawn and garden chemicals carefully. Never dump them down the drains. If you have unused products, properly dispose of them at a household hazardous waste site

Do not over-water your lawn
A healthy lawn usually requires only about 1 inch of water each week, or about 20 minutes of watering. For best results, water once a week to promote deep rooting rather than several light waterings, which causes shallow root growth and makes grass unable to tolerate dry periods. Also consider the weather; don't water your lawn if a 1 inch rain fall has occurred, and postpone watering if the forecast calls for heavy rain.

Other helpful tips

·Let your grass grow longer, this promotes deep rooting and shades the soil surface which reduces evaporation and sprouting of weeds

·Avoid mowing during the heat of the day; freshly cut grass blades can lose water quickly and dry out your lawn

·Water your lawn in the early morning, watering in the evening keeps your grass wet all night which increases the risk of disease and root damage.

·Having temporary brown outs in your lawn is ok; a few weeks of dormancy will not hurt the roots of a healthy lawn.

Inspect your septic systems every 3 years
Having your septic system properly maintained can help to save you money and reduce the chance of contaminating groundwater. Failing systems can be costly to repair and cause pollution of groundwater and nearby wetlands, streams, and lakes.

Tips on septic systems:

·Tree roots can clog and damage septic systems, so only plant grass over and nearby your septic system

·Do not park or drive your vehicles over or near a septic system, this can compact the soil and cause damage to your system.

Do not dump household hazardous wastes or used motor oil in sinks or down storm drains
When household hazardous wastes are poured down the sink, it goes through the sanitary sewage system or through your septic tank. Septic systems and sewage treatment plants are not equipped to handle hazardous waste. At treatment sewer treatment plants, the hazardous waste interferes with the biological treatment process by killing the good bacteria and contaminating the effluent that runs into our rivers and other surface waters. The biosolids that remain after the treatment process can also become contaminated, and may not be able to be reused as fertilizer.

Everything that enters into DuPont's storm drains flows directly into the stormwater system and to swales or retention/detention ponds with limited treatment. The retention/detention ponds are designed primarily to filter sediments and to hold and infiltrate stormwater to prevent local flooding. Never pour motor oil, antifreeze, fertilizer, pesticides, pet waste or other pollutants on the street or into storm drains. These pollutants can contaminate the stormwater systems and limit their effectiveness.

Tips on preventing stormwater pollution at home

·Sweep your driveways instead of hosing off to prevent pollutants from entering into storm drains

·Fix leaking crankcases and transmissions and use drip pans to prevent spills from reaching storm drains

·Clean up wet spills like oil by applying cat litter or another absorbent material

·Keep your household hazardous chemicals stored in closed and labeled containers

·Dispose of household hazardous waste at your local hazardous waste collection facility and recycle used      oil at a local oil recycling center

Remember: Only Rain Down the Storm Drain!

Department of Ecology

Draft 2012 Stormwater Management Manual for Western Washington

Puget Sound Toxics Assessment

Ecology Briefing Lead and Arsenic Clean-Up Presentation