In the United States, the serious campaign against water pollution began in 1972, when Congress passed the Clean Water Act. This law initiated a national goal to end all pollution discharges into surface waters, such as lakes, rivers, streams, wetlands, and coastal waters. The law required those who discharge pollutants into waterways to apply for federal permits and to be responsible for reducing the amount of pollution over time. The law also authorized generous federal grants to help states build water treatment plants that remove pollutants, principally sewage, from wastewater before it is discharged.
Since the passage of the Clean Water Act in 1972, most of the obvious point sources of pollution in the United States have been substantially cleaned up. Municipal sewage plants in many areas are now yielding water so clean that it can be used again. Industries are treating their waste and also changing their manufacturing processes so that less waste is produced. As a result, surface waters are far cleaner than they were in 1972. In 1990 a survey of rivers and streams found that three-quarters of these waters were clean enough for swimming and fishing. Cleaning up the remainder of these rivers and streams will require tackling the more difficult problems of diffuse, nonpoint source pollution.
Congress first took up the nonpoint source problem in 1987, requiring the states to develop programs to combat this kind of pollution. Since interception and treatment of nonpoint pollution is very difficult, the prime strategy is to prevent it.
In urban areas, one obvious sign of the campaign against nonpoint pollution is the presence of stenciled notices often seen beside storm drains: Drains To Bay, Drains To Creek, or Drains To Lake. These signs discourage people from dumping contaminants, such as used engine oil, down grates because the material will likely pollute nearby waterways. Householders are urged to be sparing in their use of garden pesticides and fertilizers in order to reduce contaminated runoff and eutrophication. At construction sites, builders are required to fight soil erosion by laying down tarps, building sediment traps, and seeding grasses.
In the countryside, efforts are underway to reduce pollution from
agricultural wastes, fertilizers, and pesticides, and from erosion caused by
logging and farming. Farmers and foresters are encouraged to protect streams by
leaving streamside trees and vegetation undisturbed; this practice stabilizes
banks and traps sediment coming down the slope, preventing sediment buildup in
water. Hillside fields are commonly plowed on the contour of the land, rather
than up and down the incline, to reduce erosion and to discourage the formation
of gullies. Cows are kept away from streamsides and housed in barns where their
waste can be gathered and treated. Increasingly, governments are protecting
wetlands, which are valuable pollution traps because their plants absorb excess
nutrients and their fine sediments absorb other pollutants. In some places, lost
wetlands are being restored. Despite these steps, a great deal remains to be
done.
In the United States, the EPA is in overall charge of antipollution efforts. The EPA sets standards, approves state control plans, and steps in (if necessary) to enforce its own rules. Under the Safe Drinking Water Act (SDWA), passed in 1974 and amended in 1986 and 1996, the EPA sets standards for drinking water. Among other provisions, the SWDA requires that all water drawn from surface water supplies must be filtered to remove Cryptosporidium bacteria by the year 2000. The law also requires that states map the watersheds from which drinking water comes and identify sources of pollution within those watersheds. While America’s drinking water is among the safest in the world, and has been improving since passage of the SDWA, many water utilities that serve millions of Americans provide tap water that fails to meet the EPA standards.
The EPA has equivalents in many countries, though details of responsibilities vary. For instance, the federal governments may have a larger role in pollution control, as in France, or more of this responsibility may be shifted to the state and provincial governments, as in Canada. Because many rivers, lakes, and ocean shorelines are shared by several nations, many international treaties also address water pollution. For example, the governments of Canada and the United States have negotiated at least nine treaties or agreements, starting with the Canada-U.S. Boundary Waters Treaty of 1909, governing water pollution of the many rivers and lakes that flow along or across their common border.
Several major treaties deal with oceanic pollution, including the 1972 Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter and the 1973 International Convention for the Prevention of Pollution from Ships (known as MARPOL). International controls and enforcement, however, are generally weak.