In the United States industry is the greatest source of
pollution, accounting for more than half the volume of all water
pollution and for the most deadly pollutants. Some 370,000
manufacturing facilities use huge quantities of freshwater to
carry away wastes of many kinds. The waste-bearing water, or
effluent, is discharged into streams, lakes, or oceans, which in
turn disperse the polluting substances. In its National Water
Quality Inventory, reported to Congress in 1996, the U.S.
Environmental Protection Agency concluded that approximately 40%
of the nation's surveyed lakes, rivers, and estuaries were too
polluted for such basic uses as drinking supply, fishing, and
swimming. The pollutants include grit, asbestos, phosphates and
nitrates, mercury, lead, caustic soda and other sodium
compounds, sulfur and sulfuric acid, oils, and petrochemicals.
In addition, numerous manufacturing plants pour off undiluted
corrosives, poisons, and other noxious byproducts. The
construction industry discharges slurries of gy