Reservoirs are critical infrastructure that redistribute surface water to meet societal purposes such as flood control, water supply, navigation, and hydropower. Reservoir design is based on the environmental (temperature, precipitation, sedimentation) and societal (water demand, energy use, regulations) conditions using the best data, science, and technology available. Reservoirs are designed to operate at full capacity for 50 to 100 years. Today, the majority of U.S. Army Corps of Engineers reservoirs' are more than 50 years old. These operations need to meet the multiple authorized purposes for the reservoir. For instance, a reservoir may be operated to keep a portion of the reservoir empty to reduce flood risk (flood control pool) and a portion filled to have water available for power, recreation, supply, and so on (Figure 1).
Figure 1: (Top) the data used to design reservoirs were collected decades ago. Water Control Plans are the guidance documents for how to operate reservoirs. These documents provide a target elevation and volume of water needed to meet each purpose for each day of the year. (Below) The process for constructing a reservoir starts with receiving congressional authorization to conduct a feasibility study. Once a reservoir is authorized, the construction phase can last several years to decades, depending on how long it takes to appropriate necessary funds.
Here, we explore the design documents of nine Army Corps reservoirs to understand the expected conditions at the time reservoirs were authorized with the conditions experienced since the reservoir began operating. Click on the above tabs to see comparisons of expected with experienced conditions. Imperial, not metric, units are used throughout this website to facilitate communication with reservoir managers in the United States. To get an understanding of how these environmental and societal indicators have changed over time across the nation, visit our interactive tool exploring national trends.
The data used in this tool can be downloaded below.