Water Quality Impacts of Land Use and Climate Change in Chesapeake Bay TMDL Mid-Point Assessment

The historic 2010 Chesapeake Bay Total Maximum Daily Load (Bay TMDL) was established for the water quality and ecological restoration of the Chesapeake Bay, and to maintain and improve the health of streams, rivers, and related ecosystems in the watershed. In 2017, a Mid-Point Assessment of the Bay TMDL was completed, for which the latest science, data, and tools were incorporated in developing Phase 3 of the Watershed Implementation Plans (WIPs). The Mid-Point Assessment also called for evaluation and incorporation of a range of climate change impacts and considerations in the Phase 3 WIPs. In addition to its vulnerability to climate change, the Chesapeake Bay is subject to socioeconomic pressures that will influence future land use, such as increases in population and intensified agricultural and economic activities. Best available data in a highly collaborative stakeholder-driven partnership setting were used to provide information needed for evaluating water quality impacts of changes in the magnitude and timing of stream-flow, sediment, and nutrient deliveries. The risks of degradation for 2025 to 2055 were assessed along with the additional level of effort required for maintaining the health of the coastal watershed. To respond to the challenges presented by these changes, the Chesapeake Bay Partnership has already committed to monitoring and assessing the trends of key indicators that include air temperature, stream temperature, precipitation, river floods, sea-level rise, and land-use change. This work is part of a broad effort to use modeling and empirical analyses to estimate effects for the different components of change, and to provide science-based information to stakeholders and managers for understanding, anticipating and preparing for potential impacts by including them in the decision-making process.