These products may be accidentally spilled onto driveways and other paved surfaces and then washed away by storm water. Once in the storm drain systems, these poisons pose a danger to plants and animals who live in the receiving streams and to the people who use the streams. Used motor oil, leftover paint and paint thinners, and other hazardous wastes are sometimes poured directly and deliberately into storm drain inlets in order to dispose of them. These toxics are then carried unfiltered and untreated into the nearest stream or waterway. Nutrients Chemicals, such as nitrogen and phosphorus, are picked up by storm water as it flows over fertilized lawns and gardens.
Nutrients also end up in storm drain systems when residents dump yard wastes into the inlets.
When algae blooms die, oxygen from the stream water is used up in the resulting decomposition process. Depleted oxygen levels cause problems for aquatic life and can result in a noxious-smelling waterway. Groundwater is important because it replenishes the flow of streams with cooler water during periods of hot and dry weather and prevents the loss of aquatic habitat due to low water levels and reduced stream flow. Help maintain dry weather flows by directing downspouts onto lawn and other vegetated areas to let the runoff soak down through the soil and into the groundwater.