The cost of nutrient reduction: A case study of Chesapeake Bay

Over $3.5 billion were spent toward nutrient controls in the Chesapeake Bay watershed between 1985 and 1996. These expenditures were based on cost-sha res between federal, state, local, and private sources and should be consid ered conservative. A comparison of point and nonpoint nutrient control expe nditures in the Bay basin showed that about 50% of the funds were directed toward agricultural best management practices and 45% were allocated for po int source nutrient reductions and combined sewer overflows (20% and 25%, r espectively). The remainder was spent on various other estuarine-targeted p rograms. Maryland was responsible for 79% of the total expenditures, 16% wa s expended by Virginia, and the remainder was attributable to the District of Columbia and Pennsylvania (4% and 1% respectively). The most costly basi n was the Patuxent (over $125 per kilogram of total nitrogen removed) and t he least costly was the Eastern Shore of Virginia, where the cost was just under $21 per kilogram of nitrogen removed. For the control practices exami ned, the analysis found that nutrient management was the least costly. Anim al waste control and low tillage were the second and third most economical nutrient management strategies. Significant reductions were achieved from point sources for both total nitr ogen (16%) and total phosphorus (53%) by 1996 Virtually all of the large re duction in point source phosphorus was a result of the phosphorus detergent ban implemented basinwide in the late 1980s. Nonpoint source nutrient redu ctions were more modest. An approximate 12% reduction in phosphorus was acc ompanied by an 8% reduction in total nitrogen loadings. Despite these nutri ent reductions, no significant improvements in bottom-dissolved oxygen leve ls were detected along the Bay mainstem during the warmer months, and the m outh of Chesapeake Bay showed marginally significant degradation during the 11-year-period. It was determined that dissolved oxygen conditions were in fluenced more by nitrogen than phosphorus reductions and that nutrient cont rols aimed at the mid-Bay region had the greatest potential for improving l ow dissolved oxygen conditions in the Bay's bottom waters.