Stormwater runoff can not only cause flooding, but spread pollution. It is a primary source of what is called nonpoint source pollution, which, according to the U.S. Environmental Protection Agency, is that originating from diffuse sources rather than from single locations such as factories and power plants. Water from rain and melting snow moves over and through soil and rock. Therefore, oil, chemicals, fertilizers, insecticides, sediment, salts from irrigation, acids from abandoned mines, and bacteria from livestock and septic systems can make their way into ecosystems and drinking water.
Fortunately, there are ways to reduce stormwater runoff. One is to plant trees. They can beautify landscapes and absorb excess carbon dioxide. Another benefit is trees’ ability to manage runoff – leaf canopies serve as a buffer so that rainfall triggers less erosion, but the surface area available provides a landing space for rain drops where they can evaporate. Water is also taken up by roots so less runs off into the environment.
The Urban Tree Canopy
Trees have been recognized as a part of many urban stormwater management programs. These include the Chicago Trees Initiative, in which the city’s Department of Streets and Sanitation Bureau of Forestry maintain over 500,000 trees, with thousands planted every year. The bureau is also responsible for responding to tree emergencies, health matters, and insect and disease issues.
The Philadelphia Water Department has implemented a system known as a stormwater tree trench. Trees above ground are connected by an infiltration structure, lined with a special fabric filled with stone and gravel, that is placed underground. A storm drain allows water to flow into the trench, where it is stored. This allows it to infiltrate and be absorbed by tree roots, or be released into the sewer system if necessary.
Eco-Friendly Landscaping Practices
Homeowners can prevent stormwater from running off and polluting water sources. Storm drains serve an important purpose, but the following tips can stop polluted water in its tracks:
Adjust gutters and downspouts, so that rainfall is directed onto plant growth areas and lawns; they can also focus water flow into containment units such as rain barrels or cisterns.
Grass clippings, soil, and fertilizer should be swept onto lawns, rather than let them clog storm drains.
On walkways and driveways, install bricks, gravel, or mulch; anything porous will help water infiltrate rather than drain and concentrate in areas that are sensitive to pollution.
Keep trash out of street gutters; rainfall will remove elements of it or entire piles of trash and deliver them to storm drains.
A good way to absorb oil spills is to use cat litter; allowing a spill or leak to fester will eventually allow rain water to mix with the oil and drain it into sewers and the ground.
Pet waste should be cleaned up right away, or else bacterial or nutrient pollution can affect the environment and ground water.
If septic systems are used, they should be inspected, maintained, and pumped regularly; if one fails, then ground water and local streams and lakes can be polluted. Professional inspections can help deal with problems beforehand.
Bad Habits Contribute to Runoff Pollution
Human habits contribute a lot to stormwater runoff. Littering can cause trash and bacteria to get into storm drains. Cigarette butts should be thrown away rather than on the ground; they can add toxins to ground water and rivers. People also like to save by washing their cars manually rather than at a car wash. However, there’s no way to collect and clean the water as washing facilities do, allowing phosphorous pollution to reach water sources.
Trash, recyclable materials, and specific household wastes should be properly stored and disposed of to prevent pollution. Chemical products are especially dangerous and include paint removers, drain cleaners, bug killers, and various types of solvents. When disposing of such products, they should be in sealed containers that are not likely to be exposed to stormwater runoff. Covering household trash is a good idea as well and, if any liquid or residue is left over from a spill outside, it should be cleaned up before rain water washes it away.
Lawn and Swimming Pool Care Can Prevent Pollution
While lawns can help with the problem, the amount of care needed (including watering) can add to the runoff. In King County, Washington, officials recommend using drought-resistant plants and compost soil and mulch, thereby using less water that can run off and improving plant growth. They also suggest avoiding fertilizers before it rains. Organic varieties are recommended, while lawn clippings can be composted or mulched.
Swimming pools can also be sources of runoff pollution. Chlorinated water in a drain system can cause environmental pollution, as can bromine, algaecides, and various cleaning chemicals. Pool water may be lacking in oxygen, so collections of it in local streams and lakes can kill off aquatic life. To prevent environmental pollution, untreated water should be given 10 days to sit so chlorine and bromine can dissipate, and removal agents can take effect. Once test kits show low enough levels and once the pH is as close to neutral as possible, then the water can be slowly released into storm drain systems.
Reducing Runoff in Specific Industries
People can do a lot by reducing stormwater runoff in expansive urban and suburban residential areas, and even in less populated rural locations. Here are a few reduction possibilities by industry.
Forestry: Erosion control, proper logging practices, and proper construction and maintenance of logging roads and trails can help reduce runoff. Also, federal and state agencies take complaints regarding questionable logging practices, as do water quality agencies.
Agriculture: Management of animal waste, reduction of pesticides and fertilizers, and control of soil erosion are good practices. For pastures and rangelands, planned grazing systems can reduce stormwater runoff, and proper disposal of chemicals and containers can prevent pollution.
Mining: Acid mine draining, and various types of reclamation projects, can contribute to pollution spread by storm water. Residents near local mining operations should voice their concerns to the community and political offices regarding stormwater runoff management at nearby mines.
Stormwater runoff can be controlled in residential, commercial, and industrial settings, in both urban and rural areas. Reducing it can prevent hazardous chemicals, bacteria, and waste from collecting in storm drains and reaching ground water, natural waterways, and sources of drinking water.