USGS Nebraska Water Science Center
The High Plains aquifer underlies 111.8 million acres (about 175,000 square miles) in parts of eight States—Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. In response to a directive from Congress, the USGS, in cooperation with local, state, and federal entities, has collected water-level data from wells screened in the High Plains aquifer and has estimated water-level and storage changes in the aquifer from the time before substantial groundwater irrigation development began (predevelopment or generally before 1950) to the present. Specifically, USGS scientists
The High Plains Water-Level Monitoring Study (HPWLMS) is the USGS response to a directive from Congress to report on water-level changes in the High Plains [Ogallala] aquifer. The directive from Congress was contained in the Water Resources Development Act of 1986 (Public Law 99-662). This law recognized the economic importance of the High Plains aquifer to the States in the High Plains region and added Title III to the Water Resources Research Act of 1984 (Public Law 98-242). Title III states that the USGS in cooperation with "...the States of the High Plains region is authorized and directed to monitor the levels of the Ogallala [High Plains] Aquifer, and report annually to Congress."
The original directive was modified by the Federal Reports Elimination and Sunset Act of 1995 (Public Law 104-66). In this legislation, Congress directed the USGS to report on water-level changes in the Ogallala [High Plains] aquifer every two years instead of annually.
These results are available in USGS Scientific Investigations Report 2017-5040 titled "Water-level and recoverable water in storage changes, High Plains aquifer, predevelopment to 2015 and 2013–15."
Boundary of the High Plains aquifer and land-surface altitude.
The "predevelopment" water level in the aquifer is defined as the water level in the aquifer before extensive groundwater pumping for irrigation, or about 1950. The predevelopment water level was generally estimated by using the earliest water-level measurement in more than 20,000 wells. Depths to water in the predevelopment period ranged from land surface to more than 300 feet below land surface.
Animation: Water-level Change in the High Plains Aquifer System, predevelopment to 2011.