The next time you're caught outside in the rain, take a look at what's running off the street, into gutters, and down storm drain inlets. Clean rainwater can quickly be transformed into an oily, murky mixture. You're looking at urban runoff, a major cause of water pollution in local creeks and the San Francisco Bay. How do day-to-day activities cause urban runoff pollution? Click on the following to learn about some of the biggest causes:
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Over the course of each year, community storm drains dump more lead, copper, zinc, and other toxic substances into the Bay than sewage treatment plants and industrial discharges combined. Other types of pollutants found in stormwater runoff include litter, food waste, automotive fluids, construction material, and yard waste. This pollution can harm fish, birds and other wildlife. It can degrade the whole web of life in the Bay, including human life – we're part of the food chain, too!
How do pollutants get into storm drains? Most are washed off streets, parking lots, and paved areas during storms. Others are deliberately drained or dumped into streets, gutters, and inlets. Some come from illicit connections to the storm drain system, and others are from materials that are spilled because of careless storage and handling practices. Here are some of the biggest causes:
- Using automobiles. Particles in auto exhaust contain toxic organics and heavy metals. Dripping motor oil and wear from brake linings and tires deposit pollutants on streets and highways.
- Maintaining vehicles. Vehicle maintenance results in drips and spills of oil, coolant and other fluids. If performed outdoors, fluids soak into asphalt and concrete pavements until they are washed away with the next storm. Washing vehicles outdoors carries pollutants directly to the nearest storm drain.
- Allowing drainage from the shop floor to flow outside. Allowing process or cleanup water to drain onto the street transports pollutants to storm drains.
- Cleaning tools and equipment outdoors. Cleaning or rinsing containers, tools, floor mats, and other items outdoors discharges pollutants such as chemicals, detergents, oils, etc.
- Dumping wastes. People looking for a “shortcut” to dispose of used oil, paint or other wastes dump them directly into storm drain inlets, causing pollution.
- Landscaping and grounds maintenance. Overuse or indiscriminate use of fertilizers and pesticides results in these materials running off landscaped areas into storm drains.
- Allowing dumpster areas to become untidy. Liquids that leak from dumpsters or garbage left outside get washed away during a storm.
- Building or remodeling facilities. Disturbing soil and vegetation during construction greatly increases erosion; sediment is a pollutant. During construction, proper material handling and waste disposal is especially important because much of the work is performed outdoors.