Runoff is water that travels over land, roadways, sidewalks and buildings, and flows to a stream, river or lake. It can be caused by rain, snow melting, and water used for irrigation of farmers’ fields, residential lawns, sports fields, and golf courses. Many different kinds of pollutants can be carried by water running off these surfaces. These include fertilizers, pesticides, oil, grease, animal waste, cigarette butts, and trash. It can also carry soil from construction sites and farmer’s fields which is called sediment.

Runoff that comes from weather events is known as stormwater. Pollutants carried by stormwater are known as Nonpoint Source Pollution, since we have no idea where it comes from. Nonpoint Source Pollution enters our streams when stormwater goes down storm drains in our streets. With the ever increasing pressures of development, pollution from stormwater runoff has become a major concern for the Metedeconk River Watershed and the Barnegat Bay Estuary.

Nutrients from fertilizer and animal waste in the form of nitrogen and phosphorus and their various compounds can cause major problems for freshwater and saltwater ecosystems. Both contribute to algal blooms within them. When large amounts of algae die, it depletes the dissolved oxygen in the water that fish and other aquatic organisms need to survive. Once their oxygen source is gone, they cannot live. This process is called eutrophication.

By using methods to control nonpoint source pollution, we can decrease the amount of pollutants entering our waterways. Such methods include rain gardens, porous pavement, bioretention basins, and rain barrels. Many of these contain native plants and soil mixtures that can “treat” stormwater, while others prevent excess water from running off our yards into our streams. These methods are also known as green infrastructure. To learn more about green infrastructure, please visit our page on this topic.

To learn more about runoff, please visit The USGS Water Science School at