Hydrology

Streamflow measurements at gage stations, collected at daily or shorter time intervals, are one of the most common data requirements for environmental flow assessments.  USGS maintains a network of gages in the United States, which can be accessed through the National Water Information System. Geospatial information of river network configurations can be accessed through the National Hydrography Dataset.

National Water Information System (NWIS)

The NWIS is a USGS database of water resourced data from over 1.5 million sites.

National Hydrography Dataset (NHD) and Watershed Boundary Datasets (WBD) 

The NHD and WBD provide spatial coverages of surface waters in the United States. The NHD includes drainage network features, such as rivers, streams, canals, lakes, ponds, coastline, dams, and streamgages. The WBD includes drainage basin boundaries delineated at various spatial scales, classified by Hydrologic Unit Codes (HUC). 

A stream gage on Cement Creek, Colorado. USGS photo.
A stream gage on Cement Creek, Colorado. USGS photo.