Box 4.1

SETTING GOALS AND DEFINING DOMAINS FOR NUTRIENT CONTROL IN THE CHESAPEAKE BAY

The Chesapeake Bay Program provides an example of dynamic planning at the regional level that addresses problems occurring across multiple jurisdictions. With specific regard to nutrients, the program has now gone through three iterations of the goal-setting process.

The Chesapeake Bay Program is the cooperative effort of the District of Columbia, Virginia, Pennsylvania, Maryland, the Chesapeake Bay Commission, the U.S. Environmental Protection Agency (EPA), and other federal agencies to restore the Chesapeake Bay. The original Chesapeake Bay Program, begun in 1978, targeted three specific issues of concern: nutrient enrichment, toxic substances, and the decline in submerged aquatic vegetation. These issues were identified as the major concerns facing the region based on existing scientific information.

In 1983, with the signing of the Chesapeake Bay Agreement, participants agreed to a major action program addressing a wide range of issues, including nutrient reduction. While many specific actions were undertaken, no overall goal for nutrient reduction was established at that time. From 1983 to 1987, program participants developed a state-of-the-art three-dimensional hydrodynamic water quality model of the watershed and conducted research to develop a better understanding of nutrient sources and their impact on the bay. As discussed further in the Assessing Risks section of this chapter and in Appendix A, nutrient enrichment can cause anoxia and hypoxia, dieback of seagrasses, and nuisance algal blooms. While the bay program was not following a formalized framework for integrated coastal management, the approach taken in regard to nutrients clearly illustrates the application of the ICM concepts presented in this report. From the mid-1980s on, the program has evolved to embody important elements of ICM, including reevaluation and feedback.

The Chesapeake Bay is the largest estuary in the contiguous United States. Nutrients enter the bay from both point and nonpoint sources throughout the watershed. Point sources include municipal and industrial wastewater discharges. Nonpoint sources include runoff from cropland and farm wastes, urban and suburban runoff, ground water discharges, and atmospheric deposition. Because the sources of nutrients to the bay occur throughout the watershed, the Chesapeake Bay Program defined its domain of analysis as the watershed that is shown in Figure 4.1. This domain includes the entire drainage area of the bay, which extends beyond the jurisdictional domains of the program participants into the states of West Virginia, New York, and Delaware. Thus, although those states chose not to be involved in the program, the analysis was designed to develop an understanding of nutrient inputs that derive from those states as well.

The Chesapeake Bay Model is a computer simulation of processes in the watershed and the bay itself. This model was developed and then used to determine the level of nutrient loadings at which deleterious oxygen depletion in the mainstem of the bay would be stopped. Using loading estimates for 1985 as the base year, it was predicted that a 40 percent reduction in nutrient loadings would mitigate the hypoxia and anoxia in the mainstem sufficiently to encourage recovery of the bay's living resources. It is important to note, how-



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