Nonpoint Source Pollution
Nonpoint source (NPS) pollution, unlike pollution from industrial and sewage treatment plants (which are discrete sources), comes from many diffuse sources. NPS pollution is caused by rainfall, snowmelt or other runoff moving over and through the ground. As the runoff moves, it picks up and carries away natural and human - made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters, and even our under ground sources of drinking water. These pollutants include:
- Excess fertilizers, herbicides, and insecticides from agricultural lands and residential areas
- Oil, grease, and toxic chemicals from urban runoff and energy production
- Sediment from improperly managed construction sites, crop and forest lands, and eroding stream banks
- Bacteria and nutrients from livestock, pet wastes, and faulty septic systems
- Salt from irrigation practices and acid drainage from abandoned mines
- Atmospheric deposition and hydromodification are also sources of NPS pollution
NPS pollution can come from both rural and urban areas. In rural areas, the causes tend to be primarily large-scale changes to the landscape, land use and hydrology caused by such operations agriculture and logging. In urban areas, population densities, combined with water-hungry non-natural landscaping and much of the rest of the land covered by impervious surfaces causes constant surface water flows that carry pollutants to inland water bodies and the ocean.
What can be done to lessen NPS pollution? For new development and significant redevelopment, we can utilize Low Impact Development techniques to design smarter to use less water, generate less runoff, and retain and reuse runoff water that is generated. We can create Ocean Friendly Gardens that require less water, fertilizers, and other chemicals.
On a personal basis, we can all do things like:
- avoid over-watering and excess chemical use
- consider planting an Ocean Friendly Garden
- wash your car at a car wash or at a location where the excess water is absorbed into the ground
- fix your car leaks
- pick up after your pet
- don't litter
- recycle and reuse
- use a broom, not a hose
- plant (appropriately), don't pave
These and other tips on how to reduce NPS pollution and keep our oceans and beaches clean, can be found in Surfrider Foundation's brochure 20 Ways to Cleaner Oceans, Waves and Beaches (pdf).
Another source of information is EPA's NPS website. In 2016 the EPA released National Nonpoint Source Program—A Catalyst for Water Quality Improvements, a report that provides details on EPA’s work to reduce water pollution from nonpoint sources through the §319 Nonpoint Source Pollution Management Program.