Methods for estimating concentrations and loads of selected constituents in tributaries to Lake Houston near Houston, Texas

Since December 2005, the U.S. Geological Survey, in cooperation with the City of Houston, Texas, has been assessing the quality of the water flowing into Lake Houston. Continuous in-stream water-quality monitors measured streamflow and other physical water quality properties at stations in Spring Creek near Spring, Tex., and East Fork San Jacinto River near New Caney, Tex. Additionally, discrete water-quality samples were periodically collected on these tributaries and analyzed for selected constituents of concern. Data from the discrete water-quality samples collected during 2005-9, in conjunction with the real-time streamflow data and data from the continuous in-stream water-quality monitors, provided the basis for developing regression equations for the estimation of concentrations of water-quality constituents of these source watersheds to Lake Houston. The output of the regression equations are available through the interactive National Real-Time Water Quality Web site (http://nrtwq.usgs.gov).