An optimization approach to evaluate the role of ecosystem services in Chesapeake Bay restoration strategies
Many of the nation’s watersheds and estuaries are suffering from the effects of high pollutant loads. Under the Clean Water Act (CWA), one of the main mechanisms for addressing these water quality impairment problems is through the establishment of total maximum daily loads (TMDLs), which limit the allowable amount of pollutant loads to a water body. Despite significant progress over the past two decades, meeting TMDL limits often presents challenging tradeoffs regarding where and how to control upstream pollutant sources. For example, relatively large and easily verifiable nutrient load reductions often can be achieved through controls of point-source discharges; however, these controls may entail relatively large costs and minimal reductions in sediment loads. In contrast, nonpoint-source controls are generally more diffuse and difficult to monitor; however, they may offer lower-cost options, more sediment control, and
other ecological benefits.
The purpose of this project is to develop an analytic framework to assist policymakers in evaluating these TMDL-related tradeoffs. The framework is designed to incorporate measures of both the cost-effectiveness and ecosystem service impacts associated with individual pollutioncontrol
projects. The inclusion of ecosystem services is a unique feature of this framework. It accounts for not only the targeted pollutant reductions but also the ancillary societal benefits— i.e., “bonus” ecosystem services—provided by certain pollution-control projects. For example, riparian forest buffers not only reduce nutrient runoff to streams, they also sequester carbon through increased biomass. When these ancillary benefits are expressed in monetary terms, they can be thought of as offsetting some of the costs of the pollution-control projects.