ADDITIONAL BENEFICIAL OUTCOMES OF IMPLEMENTING THE CHESAPEAKE BAY TMDL: Quantification and description of ecosystem services not monetized
Citation:
Wainger, L., J. Richkus, AND M. Barber. ADDITIONAL BENEFICIAL OUTCOMES OF IMPLEMENTING THE CHESAPEAKE BAY TMDL: Quantification and description of ecosystem services not monetized. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-15/052, 2015.
Impact/Purpose:
This report describes some of the benefits that might result from implementing the TMDL, but that cannot be valued in monetary terms (summarized in Table 8). These potential benefits are a direct result of decreasing nutrient and sediment loads and are by-products of implementing management practices and projects to achieve the TMDL. The first section of the report discusses the potential for reduced risks to human health that might occur from substantial reductions in pathogens (at least 19-27%), reduced risk of West Nile virus transmission to people, and reduced incidence of HABs. Although the incidence of illnesses from these causes is low, people have been shown to dramatically change their behavior in response to low health risks. Therefore, small reductions in illnesses may generate disproportionate increases in welfare by increasing recreational opportunities and enhancing feelings of safety and well-being. Further, reduced incidence of health threats would be expected to prevent economic impacts to local businesses that can result from the social amplification of these risks. The second section of the report discusses the potential for reduced nutrient, sediment, and toxic loads to enhance resilience of Bay ecosystems to future changes. Increased resilience of the Bay enhances the chances that the Bay will continue to support fisheries far into the future and could lessen the time that the Bay spends in a degraded state following major disturbance. Reduced nutrient and sediment loads are expected to increase distribution of SAV, increase abundance of selected fish species, and reduce hypoxia, all of which are thought to promote the ability of the system to tolerate and adapt to novel threats. The benefits of increased resilience may not be clear until the Bay experiences more intense climate change stressors, or unless stressors combine in undesirable ways. However, recent improvements in the Bay and case studies of other degraded systems suggest that improved water quality helps to create a system that recovers more readily from disturbance and avoids tipping points that could shift the system to an undesirable state.
Description:
Over the last 60 years, the Chesapeake Bay water quality and seagrass beds have diminished to the point that the system is less able to support abundant crabs and diverse fish, feed waterfowl, and produce safe recreational opportunities. Further, the long-term resilience of the Bay is in question as climate change, invasive species, and emerging diseases create novel stressors on this already struggling system. As a result of improved pollution management, the Bay has improved in some respects in the most recent decades and the implementation of Chesapeake Bay Total Maximum Daily Load (TMDL), which sets pollution caps, has the potential to further ameliorate problems and provide a wide variety of benefits to society. This effort supplements other efforts to monetize a range of benefits of the TMDL and explains why some key benefits that motivated the TMDL will not be included in the final dollar estimate. The purpose of this report is to provide quantification and description of the magnitude of improvements to conditions in the Bay that cannot be monetized but can be linked to human welfare. We evaluate benefit indicators (e.g., reductions in disease-causing organisms) but we are not demonstrating benefits in the strict sense because we have not evaluated what people would have been willing to pay to achieve these benefits. Yet, non-monetary benefit indices are used routinely to establish cost-effectiveness of management actions and can enrich the context in which the benefit-cost results are considered.We analyze and synthesize existing scientific literature and data to quantify and describe how the practices that the Bay states have proposed to meet the TMDL could positively affect selected ecosystem services produced by the Chesapeake Bay system. In support of public health, food supply, and recreation, we estimate that the TMDL practices collectively have the potential to decrease disease-causing pathogen loads to the Bay by at least 19-27%, reduce human exposure to West Nile Virus, and reduce incidence of harmful algal blooms. Perhaps most significantly, implementing the practices to meet the TMDL would also promote benefits derived from enhancing or maintaining Bay ecosystem resilience. We describe how resilience to multiple stresses, including climate change effects, is fostered by the regrowth of submerged aquatic vegetation, increased fish diversity, and reduced hypoxia. These changes would be expected to promote a system that recovers more readily from disturbance and avoids tipping points that could shift the system to an undesirable state.