Living on Karst
A Reference Guide for Landowners in Limestone Regions
Produced by the Cave Conservancy of the Virginias, June 1997
Pollution is an undesirable change in the physical, chemical, or biological characteristics of air, land, or water that adversely affects the living conditions for humans or other living organisms.
Water pollution is an overabundance of one or more natural or manmade substances in a body of water. Natural pollutants from soils and bedrock include sulfur, radon, and iron deposits; tannic acid and methane gas come from marshlands. People generate a host of wastes and pollutants that must be dealt with. The U.S. Environmental Protection Agency classify the two major types of manmade pollutants as point source pollution and nonpoint source (NPS) pollution. Point Source Pollution comes from a single source, such as a pipe, culvert, or ditch.
Point source pollution
is commonly associated with industrial sites, waste and water outflow pipes, or sewage treatment facilities. The signs of pollution that most people can identify are a strong odor, discharges of multicolored liquids or foam from pipes, algal growth in streams and springs resulting from sewage and other wastes, discharges from smokestacks, and refuse dumps.Point source pollution is generally controlled through state and federal permits which require a minimum level of treatment, and filtration before wastes can be discharged to surface water.
Nonpoint Source (NPS)Pollution
presents a more subtle water quality problem because it originates from widely dispersed and diverse sources, not a single outlet. Natural forces such as rain or wind often play a key role in transporting NPS pollutants to streams and aquifers. Examples of NPS pollution include sediment from eroded fields and construction sites, and runoff from backyards and barnyards containing fertilizers, pesticides, and animal wastes. Other examples of NPS pollution are the disposal of waste motor oil, paint thinner, and antifreeze in ditches and storm sewers. This also includes various pollutants attached to particles that wash off streets and parking lots. NPS pollution is even draining chlorinated swimming pools into storm sewers or streams.
Pollution continues to enter streams and groundwater in many subtle ways. NPS Pollution is the major threat to our water supply:
Soil particles eroded from the land are carried by rainwater to aquifers, streams, lakes, rivers, and bays. Metals and nutrients, such as phosphorous, attach to sediment and are carried into these water bodies by runoff.
Trash and Organic Debris
Leaves, grass clippings, garbage, and animal waste become part of the runoff entering storm drains, sinkholes, and drainage ways, clogging the underground conduit system.
Fertilizers and animal wastes contain nutrients that are essential to life, but too much can do more harm than good. Nutrients can readily enter runoff and impact water quality.
Man made chemicals can cause severe human and wildlife health problems. The use and disposal of synthetic organic compounds, metals, pesticides, herbicides, household chemicals, paint, solvents, petroleum products, antifreeze, battery acid, and roadway salt should be carefully controlled.
Parasites and bacteria present in human and animal waste are potentially disease-causing microorganisms called pathogens. Septic systems, feed lots, and other polluted runoff can carry pathogens into drinking water supplies.