UH Seal Waialee Livestock Farm Polluted Runoff Control
College of Tropical Agriculture and Human Resources
University of Hawaii

Polluted Runoff

What is polluted runoff?

stream under bridge
Highway construction next to a stream
Sediment washing into a stream from an eroded field
cows grazing
Cows in a river and grazing along the riverbank

Polluted runoff, called nonpoint source pollution in environmental science terminology, occurs when rainwater moves on the surface or through the ground carrying pollutants that have been left there from various sources. This polluted runoff flows to drainage systems and ends up impairing our streams and near-shore coastal waters. It is often difficult to trace polluted runoff to its point of origin, because it comes from many different land uses such as urban industrial and residential zones, agricultural lands, marinas, and forests.


What pollutants are in runoff?
Significant pollutant types include sediments, nutrients, toxins, floatables, and pathogens. In the simplest terms, nonpoint source pollution is any pollution that is not from a point source (an observable point of pollutant deposition onto land or into a water body).


What are the consequences of polluted runoff?
The consequences of nonpoint source pollution are well known: increased risk of disease from using water bodies for recreation, algal blooms, fish kills, destroyed aquatic habitats, and turbid waters. Some polluted runoff is from natural sources. Most, however, results from people's activities on the land and water. Since nonpoint source pollution results from how we choose to use our land and the activities we conduct, we all hold the key to its prevention.


Why animal waste management is a key to control agriculture runoff?
According to an EPA survey, agriculture is the most widespread source of pollution for rivers and lakes. Agriculture impacts 20% of assessed river miles and 14% of assessed lake acres. The state reports also indicate that agriculture impacts 59% of impaired river miles and 31% of impaired lake acres (EPA, 2000a).

Nationally, there are an estimated 1.3 million farms with livestock. About 238,000 of these farms are considered animal feeding operations (AFOs).


Comparison of Human Waste and Animal Waste in the United States
SDA estimates that operations that confine livestock and poultry animals generate about 500 million tons of manure annually (as excreted). This compares to EPA estimates of about 150 million tons (wet weight) of human sanitary waste produced annually in the United States , assuming a U.S. population of 285 million and an average waste generation of about 0.518 tons per person per year. By this estimate, all confined animals generate three times more raw waste than is generated by humans in the USA . Dairies and hog operations are the other dominant livestock types shown to contribute to excess on-farm nutrients, particularly phosphorus.

These large operations often do not have sufficient land to effectively use the manure as fertilizer. Furthermore, there is limited land acreage near the CAFO to effectively use the manure.
liquid manure from hog feeding is being land applied
Liquid manure from hog feeding being applied to land
Source U.S. EPA Producers' Compliance guide for CAFOs, 2003


Why Control of Polluted Runoff Is So Important to Hawaii
As stated in the Hawaii 's Implementation Plan for Polluted Runoff Control by the Department of Business, Economic Development and Tourism and the Department of Health, the importance of coastal water quality to the state cannot be overstated.

Tourism is Hawaii 's most important industry. Nearly six million visitors visit our state each year. Hawaii 's unique marine and terrestrial environment is among the main reasons it is chosen as a visitor destination. Clean streams and coastal waters are an integral component of that desired environment. Water quality is vital to Native Hawaiian cultural practices; leisure and recreation such as swimming, boating, snorkeling, SCUBA diving, paddling, and surfing; fishing and other food-gathering activities; and research and technology.

As the Hawaii Department of Health says in its Implementation Plan to Control Polluted Runoff, "Since nonpoint source pollution results from how we choose to use our land and the activities we conduct, we all hold the key to its prevention."