Agriculture a Major Polluter of Groundwater, Study Finds

One in five Americans may be drinking water that is contaminated from agricultural sources. This comes from a new Department of Agriculture study, the first major study on groundwater pollution the department has completed.

The findings are based on well-monitoring estimates and samplings. The authors, Elizabeth Nielsen and Linda Lee, stress that much of the data in the report are preliminary.

The study shows that the potential for groundwater pollution from farm chemicals and fertilizers is widespread across rural communities. In Iowa, for example, 94% of the counties could have contaminated groundwater supplies. In Indiana, 91% of the counties could have contaminated water.

The Southern coastal plain, the central Atlantic region, the Mississippi Delta, the northern Corn Belt, western Kentucky and the central valleys of California are the major regions that have high pesticide contamination potential.

Side effects from drinking contaminated water are hard to document. Alachlor (Lasso), found in groundwater in four states, has shown evidence of being a carcinogen. Triazine herbicides are suspected of causing long-term effects including central-nervous-system disorders. Phenoxy acid herbicides are potential leachers, and are suspected of causing nervous disorders. One study has linked 2,4-D with certain forms of cancer in farmers.

The cost of monitoring contamination levels of private wells is $2.2 billion nationwide. A typical water test for pesticide residues, conducted by a private laboratory, costs $84, a nitrate test cost $16. Homeowners who want to clean up their water can try these methods:

Activated carbon filtration (reduces pesticides): faucet-mounted, $25-50; under-the-sink, $50-$300; whole house, $500-$800.

Ion exchange (reduces nitrates): whole house, $500-$800.

Reverse osmosis (reduces pesticides and nitrates): single tap, $400-$600.

Bottled water: $7-$15 a week for a family of four.