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Table 19.2--Common sources of pollution summarized from National Water Quality Inventory Reports

Source of impairment	Description of source
Point sources
Municipal	Publicly owned sewage treatment plants that may receive indirect discharges from industrial facilities or businesses.
Storm sewers/urban runoffa	Runoff from impervious surfaces including streets, buildings, lawns, and other paved areas that enters a sewer, pipe, or ditch before discharge into surface waters.
Industrial	Pulp and paper mills, chemical manufacturers, steel plants, textile manufacturers, food processing plants.
Land disposala	Leachate or discharge from septic tanks, landfills and hazardous waste sites.
Nonpoint sources
Agriculture	Crop production, pastures, rangeland, feedlots, other animal holding areas.
Hydrologic/habitat modification	Channelization, dredging, dam construction, flow regulation; removal of riparian vegetation, streambank modification, drainage/filling of wetlands
Resource extraction	Mining, petroleum-drilling, runoff from mine tailing sites
Construction	Land development, road construction.
Silviculture	Forest management, tree harvesting, logging road construction.
Natural	Non man-induced impacts, such as floods, hurricanes, leachate from naturally occurring metals, and wildlife.

^a Storm sewers/urban runoff and land disposal include both point and nonpoint sources.




Source: U.S. Environmental Protection Agency 1998a




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