Confined Animal Production and Groundwater Protection

Our national screening model considers agricultural practices, hydrologie vulnerability, and groundwater use to identify areas that might need in‐depth study to determine whether agricultural manure use contributes to groundwater quality problems. Economic efficiency dictates that, at the margin, the benefits of reducing manure nitrogen loadings to groundwater should be at least as great as the costs. However, efficiency on a national scale is complicated by the variability of costs and benefits across groundwater basins. National mandates are unlikely to be efficient, except as minimal protection. Case‐by‐case approaches can provide efficient additional protection as needed, but they have substantial information requirements. The high cost of site‐specific data on water use, values, and hydrologic settings demands that the cases examined be selected with care. We focus on the threat of manure to groundwater use for three reasons. First, manure nutrient loadings might be on the rise because of ongoing structural changes in animal production. Second, prevention in some cases is the most economic response to threats or incidents of contamination. Replacement costs for the provision of bottled water or other alternatives are often higher than the cost of preserving existing groundwater resources. Third, the 1996 Federal Improvement and Reform Act (FAIR) authorizes $1.3 billion for environmental and conservation improvements, at least half of which must go to animal production. FAIR also mandates that the spending maximize environmental benefits per dollar. Clearly, groundwater protection is a candidate for such spending.