Suspended-sediment loads in the lower Stillaguamish River, Snohomish County, Washington, 2014–15

Open-File Report 2017-1066
By: , and 

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Abstract

Continuous records of discharge and turbidity at a U.S. Geological Survey (USGS) streamgage in the lower Stillaguamish River were paired with discrete measurements of suspended-sediment concentration (SSC) in order to estimate suspended-sediment loads over the water years 2014 and 2015. First, relations between turbidity and SSC were developed and used to translate the continuous turbidity record into a continuous estimate of SSC. Those concentrations were then used to predict suspended-sediment loads based on the current discharge record, reported at daily intervals. Alternative methods were used to in-fill a small number of days with either missing periods of turbidity or discharge records. Uncertainties in our predictions at daily and annual time scales were estimated based on the parameter uncertainties in our turbidity-SSC regressions. Daily loads ranged from as high as 121,000 tons during a large autumn storm to as low as –56 tons, when tidal return flow moved more sediment upstream than river discharge did downstream. Annual suspended-sediment loads for both water years were close to 1.4 ± 0.2 million tons.

Suggested Citation

Anderson, S.W., Curran, C.A., and Grossman, E.E., 2017, Suspended-sediment loads in the lower Stillaguamish River, Snohomish County, Washington, 2014–15: U.S. Geological Survey Open-File Report 2017–1066, 10 p., https://doi.org/10.3133/ofr20171066.

ISSN: 2331-1258 (online)

Table of Contents

  • Abstract 
  • Introduction 
  • Discharge and Turbidity 
  • Sediment Data 
  • Model Development and Summary 
  • Estimating Suspended-Sediment Load
  • Estimating Uncertainty 
  • Results 
  • Summary 
  • References Cited

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Suspended-sediment loads in the lower Stillaguamish River, Snohomish County, Washington, 2014–15
Series title Open-File Report
Series number 2017-1066
DOI 10.3133/ofr20171066
Year Published 2017
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Washington Water Science Center
Description Report: iv, 10 p.; Table
Country United States
State Washington
County Snohomish County
Other Geospatial Lower Stillaguamish River
Online Only (Y/N) Y
Additional Online Files (Y/N) Y