National Water-Quality Assessment Program
Summary of major issues and findings
Environmental setting and hydrologic conditions
Major issues and findings
Levels of some naturally occuring chemicals have the potential to affect human health and aquatic life
Fertilizers and livestock wastes increase nutrients in streams and ground water
Various factors control pesticide occurrence in streams and ground water
Urban areas are a source of trace elements and organic compounds
Environmental setting and land use influence aquatic life
Water-quality conditions in a national context
Study design and data collection
Summary of compound detections and concentrations.