Publication Summary

Between May and October 2001, the Washington State Department of Ecology conducted a streamflow assessment on the mainstem and South Fork of the Willapa River, as well as on Forks Creek, a mainstem tributary.

The streamflow monitoring was conducted in support of a temperature total maximum daily load (TMDL) study developed by Ecology′s Environmental Assessment Program. Continuous stage height recorders were installed, and several 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.

Between May and October 2001, the Washington State Department of Ecology conducted a streamflow assessment on the mainstem and South Fork of the Willapa River, as well as on Fork Creek, a mainstem tributary.

The streamflow monitoring was conducted in support of a temperature total maximum daily load (TMDL) study. The purpose of the study was to characterize the water temperature in the basin and establish load and wasteload allocations for the heat sources to meet water quality standards for surface water temperature.

Continuous stage height recorders and staff gages were installed; four to six 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.

During the study, streamflow in the Willapa River basin followed a general pattern of dry season decline, with the exception of several small storm events throughout the study period, and one large storm event in August which resulted in peak flows for the entire water year.

Link to EIM data for User Study ID ASTO0004