Document content
Water quantity, quality, and use must be considered together to fully understand water availability. Because of limitations in technology and modeling capabilities, these factors are usually assessed independent of one another. The USGS National Water Availability Assessment is the first of its kind that integrates water quantity, quality, and use to better understand water availability. The assessment uses state-of-the-art models to enable a new evaluation of the balance between natural water supply and water demand at fine scales, providing new insight on areas of the United States with a supply-use imbalance.
Key findings from the National Water Availability Assessment
-
Do we have enough water? Yes, and no. The U.S. has enough water, but not everywhere and not at all times.
At the national scale, water supply is much higher than our demand for water. However, this pattern is not true for all regions or times.
-
Limits on water availability. Water availability is affected by water quantity, quality, and flow.
Every region in the lower 48 United States faces limitations to water availability from at least one aspect of water quantity, quality, or flow.
-
Unequal access to water. Socially vulnerable Americans have a higher risk of water limitation.
Water limitation disproportionately affects socially vulnerable populations in the U.S., creating problems for equitable access to clean water.
-
Not enough rain and snow. Limited water supply can cause water imbalance.
Periods of low precipitation can have cascading effects throughout the water cycle, expanding areas of water limitation.
-
Nutrients in the water. Natural and human sources of nutrients degrade water quality.
Sources of nutrients in our water vary across the United States. Common sources of nutrients such as nitrogen and phosphorus include fertilizer and manure, atmospheric deposition, wastewater treatment plants, urban land, and a range of natural sources including stream channel and geologic sources.
-
Threats to water quality. Water quality issues can affect human and aquatic health.
Drinking water, fish consumption, and recreational water use face different water quality threats.
-
For farm, home, and energy. The largest demands for water are for crop irrigation, public supply, and thermoelectric power.
About 224,000 million gallons of freshwater are used every day for irrigation (48%), public supply (16%), and thermoelectric power (36%).
Daily freshwater use by category (of about 224,000 million gallons per day)
Share of daily freshwater use in the United States by category Use category Share of daily freshwater use Irrigation 48% Public supply 16% Thermoelectric power 36% -
From sea to shining sea. How we use water varies across the country.
The Western and High Plains regions use water primarily for crop irrigation, while the eastern half of the country uses water primarily for public supply or thermoelectric power.
Read the report, access the data, and explore interactive visualizations for these key findings at www.usgs.gov/iwaas.