Suspended sediment delivery to Puget Sound from the lower Nisqually River, western Washington, July 2010–November 2011

Scientific Investigations Report 2016-5062
Prepared in cooperation with the Nisqually Indian Tribe
By: , and 

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Abstract

On average, the Nisqually River delivers about 100,000 metric tons per year (t/yr) of suspended sediment to Puget Sound, western Washington, a small proportion of the estimated 1,200,000 metric tons (t) of sediment reported to flow in the upper Nisqually River that drains the glaciated, recurrently active Mount Rainier stratovolcano. Most of the upper Nisqually River sediment load is trapped in Alder Lake, a reservoir completed in 1945. For water year 2011 (October 1, 2010‒September 30, 2011), daily sediment and continuous turbidity data were used to determine that 106,000 t of suspended sediment were delivered to Puget Sound, and 36 percent of this load occurred in 2 days during a typical winter storm. Of the total suspended-sediment load delivered to Puget Sound in the water year 2011, 47 percent was sand (particle size >0.063 millimeters), and the remainder (53 percent) was silt and clay. A sediment-transport curve developed from suspended-sediment samples collected from July 2010 to November 2011 agreed closely with a curve derived in 1973 using similar data-collection methods, indicating that similar sediment-transport conditions exist. The median annual suspended-sediment load of 73,000 t (water years 1980–2014) is substantially less than the average load, and the correlation (Pearson’s r = 0.80, p = 8.1E-9, n=35) between annual maximum 2-day sediment loads and normalized peak discharges for the period indicates the importance of wet years and associated peak discharges of the lower Nisqually River for sediment delivery to Puget Sound. The magnitude of peak discharges in the lower Nisqually River generally is suppressed by flow regulation, and relative to other free-flowing, glacier-influenced rivers entering Puget Sound, the Nisqually River delivers proportionally less sediment because of upstream sediment trapping from dams.

Suggested Citation

Curran, C.A., Grossman, E.E., Magirl, C.S., and Foreman, J.R., 2016, Suspended sediment delivery to Puget Sound from the lower Nisqually River, western Washington, July 2010–November 2011: U.S. Geological Survey Scientific Investigations Report 2016-5062, 17 p., http://dx.doi.org/10.3133/sir20165062.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Abstract 
  • Introduction
  • Methods of Data Collection and Analysis
  • Suspended Sediment Delivery
  • Summary
  • Acknowledgments
  • References Cited
  • Appendixes A-D

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Suspended sediment delivery to Puget Sound from the lower Nisqually River, western Washington, July 2010–November 2011
Series title Scientific Investigations Report
Series number 2016-5062
DOI 10.3133/sir20165062
Year Published 2016
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Washington Water Science Center
Description Report: vi, 17 p.; Appendixes A-D
Country United States
State Washington
Other Geospatial Lower Nisqually River
Online Only (Y/N) Y
Additional Online Files (Y/N) Y