A broad range of chemical constituents is measured at the eight stations in the network. Samples are collected 6 to 10 times per year, depending on the local site characteristics. At the upper-basin sites, samples are collected on the basis of reservoir releases to cover a broad range of river discharge. Trend analysis of specific constituents yield information on storm-runoff characteristics of each subbasin and human and natural activities characteristics of each subbasin. The network and frequency of sampling provides information to resource managers and regulatory agencies on this important question.
Some miscellaneous record exists for most stations before the period of record.
About 40 streamflow-gaging stations in the program are used to determine the transport of selected chemical constituents and sediment through the river systems. Future products for the Colorado River Basin may include annual fact sheets that will describe specific water- quality issues and related data analysis. As of 1999, data are being analyzed for the Colorado River that may result in modification of the existing program to better meet the information needs of the basin. Chemical-flux calculations are being made at each site along with interpretations of reservoir effects on mass transfer of chemicals within the river system. Results for each constituent are being evaluated to determine the importance of the constituents in the program, and new constituents and site-specific studies may be added.