Publication Summary

Between May and October 2001, the Washington State Department of Ecology measured flows and developed continuous stage records at five sites on the Stillaguamish River and selected tributaries. The streamflow monitoring was conducted in support of a temperature total maximum daily load (TMDL) study developed by the Department of Ecology. Streamflow in the Stillaguamish basin followed a general pattern of dry season decline, with the exception of a 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.

Between May and October 2001, the Washington State Department of Ecology measured flows and developed continuous stage records at five sites on the Stillaguamish River and selected tributaries. Two of the five stations were located on the South Fork Stillaguamish River, one at the U.S. Forest Service Verlot Campground, and one at Snohomish County′s River Meadows Park. One station was located on the North Fork Stillaguamish River, in the Mount Baker/ Snoqualmie National Forest. One station was located near the mouth of Deer Creek, a tributary to the North Fork. One station was located near the mouth of Pilchuck Creek, a tributary to the mainstem Stillaguamish River. A rating curve was also developed at one additional site on the North Fork Stillaguamish River at Oso.

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

Continuous stage height recorders and staff gages were installed, and 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 station.

Streamflow in the Stillaguamish basin followed a general pattern of dry season decline, with the exception of a 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.