J.D. Bredehoeft 1983 There is growing documentation that a significant portion of the Nation's fresh ground water in the densely populated areas of the USA is contaminated. Because of the slow rates of ground-water movement, ground water once contaminated will remain so for decades, often longer. Cleanup of contaminated ground water is almost always expensive and often technically unfeasible; the expense is often prohibitive. -from Author application/pdf 10.1029/RG021i003p00760 en American Geophysics Union Ground water: a review. article