In 2006, the U.S. Geological Survey (USGS), in cooperation with the Texas Department of Transportation, began collecting annual and approximately quarterly-series peak streamflow data at streamflow-gaging stations in small- to medium-sized watersheds in central and western Texas, along with selected flood-hydrograph data at a subset of these stations. The data were primarily collected from a type of USGS streamflow-gaging station known as a crest-stage gage (CSG) station. The CSGs record peak stage, or maximum gage height (elevation of water surface above a local vertical datum), at the stations during storm events. Established and widely-used indirect methods of peak streamflow estimation, such as culvert-flow, slope-area, and flow-over-road methods, are used in conjunction with peak gage-height data to create the database of peak streamflow described herein.
The data collected during 2006–15 at the CSG network in central and western Texas were collected at some of the same locations where peak-streamflow data were collected during 1966–74, 1994–97 and 2005. A database of 832 peak streamflow records for which 469 peaks are determined to be the annual peak for the corresponding water year is documented through water year 2015 for 52 CSG stations. The water year is designated by the calendar year in which it ends. Because of the complex nature and vagaries of field-data collection along with uncertainties in minimum-computable streamflow for any particular station and circumstances in time, many of the reported peak streamflows are listed as either inequalities (less than or greater than a streamflow threshold) or intervals (streamflow within a lower and upper bounds). The database reported represents an important intermediate milestone in the 20-year planning horizon of the CSG network.