National Water Census
Water availability is intricately linked to water quality, and vice versa. For example, even plentiful water supplies might not be suitable for use if water quality is impaired. Therefore, the Water Census will work in close cooperation with the National Water-Quality Assessment (NAWQA) Program to identify national and regional issues where new science is necessary to better integrate the question of quality into the analysis of water availability.
The NAWQA Program has taken an interdisciplinary approach to evaluating the quality of streams and groundwater nationwide since 1991, and has been implemented in three Cycles. Cycle 1 (1991-2000) produced baseline assessments of the quality of streams, groundwater, and aquatic ecosystems in 51 of the Nation's largest and most important river basins and aquifers. Cycle 2 (2001-2012) built on the assessments through: (1) increased emphasis on assessment of long-term trends; (2) assessments of water quality in major river basins that discharge into some of the Nation's key estuaries (3) regional assessments of water quality in 19 of the Nation's 62 principal aquifers; and (4) an initial assessment of contaminants in currently used sources of drinking water.
The NAWQA Program is currently examining connections between water quality and water availability as part of the Cycle 3 studies. Of particular importance will be the development and application of water-quality models that integrate information on water quality, chemical use, land use, and environmental factors to explain how water-quality conditions vary regionally and nationally. This is key because managing contaminants requires far more information than what can be affordably measured and monitored for all the places, times, and contaminants that are important. Models are essential tools for cost-effective management of water resources because they enable water-quality understanding to unmonitored areas under a range of possible circumstances.