the rundown on
polluted runoff
Polluted runoff is a major problem throughout the United States and the rest of the world. Whenever it rains, a toxic soup of chemicals and bacteria flows out of our cities and fields and into our waterways. Eventually, these pollutants can lead to the poisoning of aquatic wildlife or the creation of vast dead zones where there isn't enough oxygen for marine life to survive. And, our beaches and rivers can be unsafe for swimming and other recreational activities due to high bacteria levels and other toxins. So what can YOU DO to prevent your local beach from becoming polluted?
the environmental impacts of polluted runoff
Runoff is a general term that indicates when water runs across the ground and into some waterway, rather than filtering in through the soil and reaching groundwater. Runoff is part of the natural water cycle, as many types of natural soils are too dense for water to filter (or infiltrate) when it rains. It becomes a problem, however, when it occurs in intensive agriculture areas or urban areas. On its way downhill, streams of runoff pick up whatever is lying in its path – excess fertilizer, pesticides, pet waste, oil and sediment.
Polluted runoff is produced by two main processes. The first is called urban runoff. It occurs when rain falls in our urban and suburban areas, or when we over-water our lawns and wash our cars, driveways and sidewalks. Prior to development, most of this water would have sunk into the ground. With development, though, roofs get added, streets and driveways get paved, and soils get compacted. These changes can increase the amount of water that runs off in these areas by over 100%. This runoff carries pollutants – oil from our cars, pet waste, various toxic metals that have eroded from cars, and other household chemicals that are dumped in streets, driveways and yards.
In Southern California, beaches are often closed during winter rainstorms for days or weeks, and people year-round can become ill from bacteria carried from storm drains. A recent study has determined that up to 1.5 million people a year are sickened by bacteria pollution on Southern California beaches . In another report, the US Environmental Protection Agency reported that the 4,000 monitored beaches along the US Coast were closed for over 27,000 days in 2005, an all-time record and 30% greater than in 2004 .
In the second case, runoff occurs because we apply too much water to irrigated agricultural and landscaped areas. The excess water that can't be used by plants or can't filter into the soil runs off into ditches, canals, streets and storm drains. This excess irrigation water can carry huge quantities of pesticides, herbicides, or nutrients that are harmful in surface water.
As an example, each year a “dead zone” forms at the mouth of the Mississippi River. In 2005, this zone was over 4,500 square miles in area, and in other years it has reached 7,000 square miles. This zone is caused by the runoff of fertilizers from Midwestern farms, leading to algae blooms that deplete the Gulf of Mexico of oxygen. Few marine animals outside of the simplest organisms can survive these conditions.
what you can do to reduce runoff
Although cities around the country are spending billions trying to curb polluted urban runoff, they will get nowhere without the help of residents. Even the largest treatment plants cannot treat the runoff from moderate rain storms.
We all have a major role in these efforts. Most urban runoff starts as rain falling on our property or on the parking lots we use. The dog waste you leave on the side of the road today could be at the beach tomorrow.
Fortunately, there are many solutions we can employ that reduce runoff AND have other benefits.
1. Capture and Reuse Stormwater For Irrigation
- Install rain barrels or cisterns at the end of gutter downspouts – not only do you reduce runoff, but you store free water for irrigation use. People have used cisterns for thousands of years to store water for later use. Today, you can help solve one of our most pressing modern environmental problems with this proven technology.
See rain barrels and other rain storage systems. - Design some of your landscaping areas to function as rain gardens. Rain gardens are the same as regular gardens except for three things: they are slightly depressed so that they can store water, they employ plants that can tolerate wet conditions, and they sometimes have gravel placed underneath them to increase drainage. Stunning gardens can be created using water-tolerant plants and flowers. Find landscape architects in your area who can help with rain gardens.
- Install dry wells. Dry wells are pits filled with crushed stone that route runoff underground before it gets to the street or local stream. They are easy to build, and offer your plants a greater supply of underground water. Oftentimes, dry wells receive runoff from your gutter downspouts, or from a drain installed across your driveway. Find a landscape architect in your area who can assist with dry wells and other stormwater projects.
2. Reduce paved surfaces. Runoff comes from our rooftops, driveways and paved pathways. With slight changes, these areas can be made much more river-friendly. Find landscape architects or general contractors in your area who can help with runoff-reducing paving projects.
- Where possible, use paths and surfaces constructed out of pavers with spaces in between or other materials such as decomposed granite rather than solid concrete. This allows water to filter in rather than drain to the street and storm drains.
- Replace long driveways with paved tire pathways, so that the area in between is natural and allows water to penetrate the ground. Use “permeable” paving options.
3. Plant trees that grow over paved surfaces or rooftops. Trees stop water from hitting the ground by trapping it in the leaves and branches. It either evaporates there, or else runs to the edges of the tree's canopy and falls to the ground there (called the drip line). The strategic planting of trees over paved surfaces or roofs can not only reduce stormwater, but will also help your house be cooler and more energy-efficient (not to mention beautiful!).
4. Practice good housekeeping. You might not be able to eliminate all runoff, so make sure that which you can't eliminate is clean.
- Clean up after your pets. Pet wastes are some of the biggest sources of bacteria in our waterways. Clean it up before it runs off during the next storm.
Find biodegradable pet waste bags. - Reduce use of toxic pesticides and herbicides. Many herbicides and pesticides don't discriminate. They'll kill whether it's the weed in your lawn or the plant down next to the lake. Use natural alternatives where possible. If you need to bring out the heavy artillery, use only as directed and in as small of quantities as possible. See sustainable gardening products.
- Use lower-strength organic fertilizers, and follow the application instructions. Excess fertilizer that makes its way into our rivers and oceans is the chief cause of the algae blooms that can sicken people and deprive fish and shellfish of the oxygen they need to survive. Most of us over-fertilize our lawns and gardens, so read and follow the instructions carefully! And, use lower-strength organic fertilizers whenever possible. See sustainable gardening products.
