Water Supply
When drought impacts affect the water supply—the water levels in streams, reservoirs, and groundwater—it is known as hydrological drought. Periods of drought can lead to inadequate water supply, threatening the health, safety, and welfare of communities.
Hydrological Drought
According to the National Drought Mitigation Center, hydrological drought results from precipitation shortfalls on the surface or subsurface water supply—affecting streamflow, reservoir and lake levels, and groundwater.
The map depicts streamflow conditions compared to historical streamflow conditions for the day of the year. U.S. Geological Survey stream gages are displayed alongside current drought conditions from the U.S. Drought Monitor. Learn more.
The National Weather Service's Weather Prediction Center (WPC) produces Quantitative Precipitation Forecasts (QPFs) that depict the amount of liquid precipitation expected to fall in a defined period of time. QPFs issued by the WPC are defined as the expected "areal average" (on a 20 x 20 km grid) in inches. This map shows the 7-day total QPF. Learn more.
Streamflow Percentiles
U.S. Drought Monitor
Predicted Inches of Precipitation
Groundwater and soil moisture drought indicators based on terrestrial water storage observations derived from GRACE satellite data and integrated with other observations, produced each week by NASA
The National Water Dashboard is an interactive map viewer that shows provisional real-time water data from more than 13,000 USGS observation stations in context with weather-related data from other
The Advanced Hydrologic Prediction Service (AHPS) provides flood and drought related forecasts for the United States based on streamgage data.
The "groundwater watch" web pages group related wells and data from active well networks, and provide basic statistics about the water-level data collected by USGS water science centers for Coopera
A resource for information about the USDA Natural Resource Conservation Service's work relating to water quality and quantity.
The Experimental Surface Water Monitor provides forecasts and current conditions for soil moisture and cumulative runoff in the United States.
Impacts and Related Content
Timing
According to the National Drought Mitigation Center, the effects of hydrological drought are usually not seen until much later than those from meteorological and/or agricultural drought, as it takes longer for impacts—such as decreases in groundwater levels—to be seen in the hydrological system.
Competition/Restrictions
Groundwater and surface water from rivers and reservoirs are used in many ways—including electricity generation, recreation, wildlife habitat, flood control, and agricultural irrigation. Drought conditions can exacerbate competition for the use of the depleted resource and trigger restrictions based on prior water rights, creating conflict between water users.
Conjunctive Water Management
To manage for drought and climate extremes, water managers increasingly coordinate the use of both surface water and groundwater to utilize overall water supply more efficiently and diversify water management portfolios.
By Sector | Water Utilities
Drought impacts on water utility operations range from loss of water supply to increased costs and reduced revenues.
Drought resilience for water utilities includes the ability to respond to immediate water supply threats, as well as considering long-term conditions and planning for permanent solutions.
Forecast-Informed Reservoir Operations (FIRO)
FIRO is a proposed management strategy that uses data from watershed monitoring and modern weather and water forecasting to help water managers selectively retain or release water from reservoirs in a manner that reflects current and forecasted conditions. Western water managers require improved long-range forecasting of precipitation to more effectively manage water resources for both extreme wet and dry conditions. FIRO is being developed and tested as a collaborative effort in the Russian River Basin (Lake Mendocino), the Santa Ana River Basin (Prado Dam), and the Yuba-Feather River Basins.
