The Sandhills Aquifer System, a vital component of the High Plains Aquifer system, is a regional aquifer located beneath the Sandhills region of Nebraska. Spanning across north-central Nebraska, the system encompasses over 20,000 square miles of land, stretching from the Canadian River in southwestern North Dakota to the Platte River in southern Nebraska, then westward to the Wyoming border. The aquifer system is a critical source of fresh groundwater, supporting the region's agricultural, municipal, and industrial activities.

Geologically, the Sandhills Aquifer System is a multi-layered system consisting of the Arikaree Group and the White River Group, two geological formations composed primarily of unconsolidated sediments, including sand and gravel, deposited during the Miocene and Pliocene epochs, approximately 20 million to 5 million years ago. These sedimentary deposits are underlain by a layer of impermeable shale, known as the Brule Formation, which separates the aquifer system from the underlying Prairie Formation. This geologic arrangement allows for efficient recharge and storage of groundwater, making the Sandhills Aquifer System a valuable resource for the region.

Recharge of the aquifer system is primarily facilitated through the infiltration of precipitation in the surrounding uplands, including the Badlands of Nebraska, a region characterized by rolling hills and deeply incised gullies, located near the town of Crawford, Nebraska. This upland area receives relatively higher amounts of rainfall compared to the surrounding Sandhills region, resulting in increased recharge rates. In addition to precipitation, the Sandhills Aquifer System also receives recharge from the numerous ephemeral streams that intersect the area, including the Snake River near Ainsworth, Nebraska.

The Sandhills Aquifer System supplies water to numerous communities, including the town of Ogallala, which is situated over the Ogallala Well Water Level Monitoring, a key groundwater monitoring site. The city relies heavily on the aquifer system for its municipal water supply. Irrigation demands account for a significant portion of groundwater withdrawals from the aquifer system, particularly in areas with high agricultural activities, such as the North Platte River valley near the city of North Platte.

Despite the importance of the Sandhills Aquifer System, concerns have been raised regarding the sustainability of groundwater use, given the high demands placed on the resource. Decreases in groundwater levels, known as cone of depression, have been observed in areas with intensive irrigation activities, such as the vicinity of Sutherland, Nebraska. This has led to efforts to improve water management practices and optimize groundwater use efficiency.

One notable example of a groundwater conservation initiative in the region is the Central Platte Natural Resources District's (CPNRD) multi-year study, launched in partnership with the United States Geological Survey (USGS) and the University of Nebraska-Lincoln, to evaluate the effects of groundwater use on the Sandhills Aquifer System. This research effort aims to provide valuable insights into the long-term sustainability of the aquifer system, enabling resource managers and policymakers to make informed decisions about water resource management.

Studies such as these reinforce the importance of understanding and managing groundwater resources like the Sandhills Aquifer System. By balancing human needs with the need for groundwater sustainability, the long-term viability of the aquifer system can be ensured, supporting continued economic development, agricultural productivity, and environmental stewardship in the region.