Central Nebraska Basins NAWQA Study Unit

What is the National Water-Quality Assessment Program?

During the past 25 years, our Nation has sought to improve its water quality; however, many water-quality issues remain unresolved. To address the need for consistent and scientifically sound information for managing the Nation's water resources, the U.S. Geological Survey began a full-scale National Water-Quality Assessment (NAWQA) Program in 1991. This program is unique compared to other national water-quality assessment studies in that it integrates the monitoring of surface- and ground-water chemistry with the study of aquatic ecosystems. The goals of the NAWQA Program are to (1) describe current water-quality conditions for a large part of the Nation's freshwater streams and aquifers, (2) describe how water quality is changing over time, and (3) improve our understanding of the primary natural and human factors affecting water quality.

Assessing the quality of water in every location of the Nation would not be practical; therefore, NAWQA Program studies are conducted within a set of areas called study units. These study units represent the diverse geography, water resources, and land and water uses of the Nation. The Central Nebraska Basins, Nebraska, is one such study unit designed to supplement water-quality information collected in other study units across the Nation while addressing issues important to the Central Nebraska Basins.

Entering a New Decade

In 2001, the NAWQA Program began its second decade of intensive water-quality assessments (Cycle II). The NAWQA Program has become a primary source for long-term, nationwide information on the quality of streams, ground water, and aquatic ecosystems. The goals of NAWQA remain unchanged since 1991.

During Cycle II, NAWQA scientists plan to revisit 42 study units that were assessed in the first decade. For Cycle II assessments, study units were selected that represent a wide range of important hydrologic environments; contain critical contaminant sources, including agricultural, urban, and natural sources; and include more than 60 percent of national water use for drinking and irrigation. Many of the predominantly agricultural study units and most of the large urban areas included in the first cycle of NAWQA assessments were retained for Cycle II. Central Nebraska is one of the most intensively agricultural areas being examined in Cycle II, as determined from the extent of agricultural land and intensity of estimated pesticide and fertilizer use.