Data Access Tools

The U.S. is sub-divided into successively smaller hydrologic units which are classified into four levels: regions, sub-regions, accounting units, and cataloging units. Each unit is identified by a unique hydrologic unit code (HUC) consisting of two to eight digits based on its classification. This site provides information and data for current and historical hydrologic units, names, and numbers.

During major storms or other short-term events, the USGS collects streamflow and additional data (including storm tide, wave height, high-water marks, and additional sensor deployments) to aid in documenting flood events. The USGS Flood Event Viewer provides convenient, map-based access to downloadable event-based data.

This mapper identifies USGS Federal Priority Streamgages (FPS). FPS are monitoring stations that track the amount of water in streams and rivers across the Nation to meet long-term federal information needs. They are strategically positioned to serve as a backbone for the larger National Streamflow Network that is operated in cooperation with over 1,200 federal, state, tribal, and local agencies.

Water quality is essential for understanding water availability by providing insights into the drivers of change and possible availability constraints. Using data from eight monitoring organizations including the USGS, the Multisource Water-Quality Trends in the Delaware River Basin mapper shows changing water-quality trends from 2008-2018 in rivers and streams across the Delaware River Basin.

Since 1969, USGS has collected water-quality data along the deep-channel longitudinal axis of the San Francisco Bay-Delta system at 37 fixed locations spaced 3-6 kilometers apart. The Water Quality of San Francisco Bay Data Query provides access to the entire dataset.

The Map and Data Products page offers bulk download of the Fire Danger Forecast data suite.