Publication Summary

Between May 2002 and May 2004, the Department of Ecology conducted a streamflow assessment on the Wenatchee River and selected tributaries. The project was divided into two study years.

The streamflow assessment was conducted in support of a Total Maximum Daily Load (TMDL) study for temperature, dissolved oxygen, pH, and fecal coliform. Continuous stage height recorders were installed at four sites during each of the two study years, and discharge rating curves were developed for each site by relating various stage height values to corresponding discharge measurements. Rating curves were developed at five additional sites with no continuous monitoring during year one of the study.

From May 2002 through May 2004, the Washington State Department of Ecology conducted a streamflow assessment on the Wenatchee River and selected tributaries. The project was divided into two study years. The first year focused on the mainstem Wenatchee River and upper-watershed tributaries, and the second year focused on lower-watershed tributaries.

The streamflow assessment was conducted in support of a Total Maximum Daily Load (TMDL) study for temperature, dissolved oxygen, pH, and fecal coliform. The purpose of the study was to evaluate temperature, pH, dissolved oxygen, fecal coliform, and other ancillary parameters to form the basis for a proposal to set instream water quality targets to meet water quality standards and allocate contaminant loads to sources.

Continuous stage height recorders and staff gages were installed at four sites during each of the two study years, and at least four discharge measurements were taken at each site. Discharge rating curves were developed for each site by relating various stage height values to corresponding discharge measurements. Applying these rating curves over the range of stage height enabled a continuous record of discharge to be developed at each site. Rating curves were developed at five additional sites during year one of the study. No continuous monitoring took place at these sites.

Ten of the fourteen sites monitored in this study produced discharge data that are accurate to within 10 percent. Aquatic weed growth and sedimentation were the primary causes of error in discharge data.