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Assessment of suspended-sediment transport, bedload, and dissolved oxygen during a short-term drawdown of Fall Creek Lake, Oregon, winter 2012-13

August 8, 2014

The drawdown of Fall Creek Lake resulted in the net transport of approximately 50,300 tons of sediment from the lake during a 6-day drawdown operation, based on computed daily values of suspended-sediment load downstream of Fall Creek Dam and the two main tributaries to Fall Creek Lake.


A suspended-sediment budget calculated for 72 days of the study period indicates that as a result of drawdown operations, there was approximately 16,300 tons of sediment deposition within the reaches of Fall Creek and the Middle Fork Willamette River between Fall Creek Dam and the streamgage on the Middle Fork Willamette River at Jasper, Oregon.


Bedload samples collected at the station downstream of Fall Creek Dam during the drawdown were primarily composed of medium to fine sands and accounted for an average of 11 percent of the total instantaneous sediment load (also termed sediment discharge) during sample collection.


Monitoring of dissolved oxygen at the station downstream of Fall Creek Dam showed an initial decrease in dissolved oxygen concurrent with the sediment release over the span of 5 hours, though the extent of dissolved oxygen depletion is unknown because of extreme and rapid fouling of the probe by the large amount of sediment in transport. Dissolved oxygen returned to background levels downstream of Fall Creek Dam on December 18, 2012, approximately 1 day after the end of the drawdown operation.

Publication Year 2014
Title Assessment of suspended-sediment transport, bedload, and dissolved oxygen during a short-term drawdown of Fall Creek Lake, Oregon, winter 2012-13
DOI 10.3133/ofr20141114
Authors Liam N. Schenk, Heather M. Bragg
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Open-File Report
Series Number 2014-1114
Index ID ofr20141114
Record Source USGS Publications Warehouse
USGS Organization Oregon Water Science Center
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