By Aaron Whittemore, Center for Sustaining Agriculture and Natural Resources, Washington State University

The Grand Coulee Dam is one of a system of dams on the Columbia River used for water storage, energy production and flood control. Credit: Bureau of Reclamation.
Reservoirs are common infrastructure across the globe, with myriad benefits and costs attached. In the Pacific Northwest, for example, reservoirs are used for water storage, energy production, and flood control, but they impact salmon by blocking passage to spawning and rearing habitat and also lose water to evaporation. However, few people know that reservoirs are also a significant source of greenhouse gases, releasing emissions on the scale of thousands of teragrams (Tg) per year, globally. For reference, the entire U.S. usually emits between six and seven thousand teragrams of greenhouse gases each year. Estimates of reservoir emissions have remained uncertain, though, making it hard to find ways to reduce these emissions. Dr. John Harrison from Washington State University teamed up with colleagues from the University of Quebec at Montreal to try to narrow down estimates of global reservoir greenhouse gas emissions, which could help pinpoint where limiting emissions would be most helpful and illuminate specific methods for doing so. Continue reading