Reservoir Storage Capacity Change (ResCap)

Overview

Storage capacity is an essential reservoir metric that is directly linked to various water management and energy objectives. Accurate reporting and tracking of change in storage over time is crucial for the safe and reliable operation of the associated dam. While storage information is available for many reservoirs through the National Inventory of Dams, additional details, e.g. water elevation levels as well as changes over time are not included.

This dataset contains reservoir storage capacities based on conducted surveys in CONUS. To represent changes in a reservoir’s storage over time, the storage capacity as determined by the first and last conducted survey is listed. The level of detail of surveys can vary greatly and improved with technological advancements. Therefore, the type of survey and year when it was conducted is noted. To ensure a fair comparison of storage capacities, the water elevation level along with the corresponding operation of the dam is reported. Structural changes, e.g. heightening of a dam will have an influence on the storage capacity and are therefore also mentioned. A total of 739 different reservoir storage capacity comparisons are listed, with some reservoirs represented more than once (storage capacity comparison at different water elevation levels).

Methodology

Data were acquired from USBR reservoir survey reports, TWDB lake survey reports and elevation-area-capacity tables, the RSI Web Portal and the NID (USACE, 2024). Initial storage capacity along with year and type of survey record is compared to the most recent reported storage capacity, survey type and year. Comparison elevation in feet as well as comparison elevation type were either extracted from survey reports (USBR, TWDB) or the Web Portal (RSI) and in some cases cross-referenced with data from other sources (Water Management Data, USACE, Water Data for Texas, TWDB).

References:

USBR. 2025. Technical Service Center. Reservoir Surveys. Available at https://www.usbr.gov/tsc/techreferences/reservoir.html

Texas Water Development Board. 2025. Surface Water. Lake Surveys. Available at https://www.twdb.texas.gov/surfacewater/surveys/completed/list/index.asp

USACE. 2024. Enhancing Reservoir Sedimentation Information Web Portal (RSI). Retrieved September 5, 2024. Restricted access.

USACE. 2024. National Inventory of Dams. Retrieved September 4, 2024. Available at https://nid.usace.army.mil/#/downloads

USACE. 2025. Water Management Data. Available at https://water.usace.army.mil/ TWDB. 2025. Water Data for Texas. Reservoirs. Available at https://www.waterdatafortexas.org/reservoirs/statewide