Despite the tremendous progress that has been achieved in water pollution, almost 40% of the . waters that have been assessed by states do not meet water quality goals. About 20,000 water bodies are impacted by siltation, nutrients, bacteria, oxygen depletion substances, metals, habitat alterations, pesticides, and toxic organic chemicals. With pollution from point sources being dramatically reduced, nonpoint source pollution is the major cause of most water that does not meet water quality goals. About 50 to 70% of the assessed surface waters are adversely affected by agricultural nonpoint source pollution caused by soil erosion from cropland and overgrazing and from pesticide and fertilizer applica.
