Rainwater picks up chemicals, metals, and other toxic substances when it runs off our roofs, streets, and lawns.

Development & Impervious Surfaces

Impervious areas are places where the ground is covered by a hard surface so that water "runs off" instead of soaking naturally into the ground. Impervious surfaces include roads, sidewalks, driveways, parking lots, rooftops, and many other hard surfaces. When impervious surfaces are created through development, less rainwater soaks into the ground. If rainwater cannot soak into the ground, or infiltrate, it becomes runoff. As more and more natural spaces are converted into developed areas, more and more stormwater runoff is created. Without careful comprehensive land planning, this increase in the volume of stormwater pollution can be a growing problem.


Fertilizers, being composed of nutrients such as nitrogen and phosphorus, can help plants grow, but when applied in excessive amounts fertilizers can harm water quality and aquatic life. When it rains, the excess fertilizer and nutrients that have not been absorbed by the lawn or garden plants are carried by stormwater runoff into the nearest stream, river, or other water body. Excessive nutrients in water can cause algae to grow, which depletes the oxygen in the water. Low levels of oxygen in water can harm aquatic wildlife and cause a widespread fish kill. You may not see the effect of fertilizers in stormwater runoff right where you live, but their detrimental effects are very apparent in Oklahoma's waterways.


Litter is pollution. Litter thrown on the ground can end up in our storm drains, ditches, and streams. Stormwater runoff, or rain and melting snow, carries large quantities of litter to streams, rivers, and lakes. Litter is often made of plastics, and plastics take hundreds of years to decompose and can be harmful to birds and animals that become entangled in it or mistake it for food.

Pet & Human Waste

Bacteria can come from pet, wildlife, or human waste. It is easily carried to nearby waterways by rain and melting snow. Human waste can enter streams and rivers through sanitary sewer overflows, leaks in the sanitary sewer system, or failing septic systems. Pet waste is primarily from dogs, although cats contribute some as well. Waste that is carried by rain and melting snow into our streams, lakes and rivers can cause bacterial contamination in the water. It can be dangerous for you and your family to fish, boat or swim in water contaminated with bacteria because it can cause diseases and serious infections in animals and people.


Vehicles are a source of many pollutants in stormwater runoff. Oil, antifreeze, and other fluids often leak from cars onto parking lots or are spilled during maintenance. The normal use of our automobiles creates vehicle exhaust that causes copper and other heavy metal dust to settle on surfaces. Stormwater runoff then carries these contaminants to streams and rivers, where they can eventually become concentrated enough to disrupt the natural environment for aquatic life.