Research and Development Office

Pilot Studies of Reservoir Sustainability Options - Flushing and Sluicing

Project ID: 8235
Principal Investigator: Sean Kimbrel
Research Topic: Sediment Management and River Restoration
Funded Fiscal Years: 2016, 2017 and 2018
Keywords: None

Research Question

How can we develop and improve guidelines for reservoir sustainability planning for Reclamation Reservoirs? In
particular, how can we improve the assessment, planning, decision making, and implementation of sediment
management options such as flushing and sluicing for various sizes of reservoirs?
This study builds upon the research project titled 'Developing Guidelines for Formulating Reservoir Sustainability
Plans' from Fiscal Years 2013 and 2014 (funded by the S&T Program), where a framework of the process of
defining available options, new potential alternatives, and additional needs to achieve reservoir sustainability were
developed.

Need and Benefit

plans developed in the FY 2013/2014 research project. In particular, the planning of reservoir sediment
management options such as flushing and sluicing at Reclamation reservoir pilot sites, where these alternatives
could possibly be implemented in order to extend the useful life of the facility.
There is interest conducting this work and collaborating at two reservoir sites in the Pacific Northwest Region,
Black Canyon and American Falls. Both reservoirs have experienced adverse impacts of passing reservoir sediment
downstream when the reservoir is drafted to low elevations during periods of low inflows, such as in drought
conditions, near the end of the irrigation season, for inspection, or for construction or repairs. High sediment
loads during low flow periods can be defined as mistimed or 'disjointed' sediment discharges. As a result,
previously deposited reservoir sediments are eroded and transported downstream at high sediment
concentrations during lower outflows which have a reduced sediment transport capacity to pass sediments once
below the facility, and high rates of downstream deposition can occur, which can impact downstream aquatic
species (e.g., smothering critical egg incubation sites) and in-channel facilities (e.g., small diversions dams and
canals).
Other potential partners beyond the Pacific Northwest Region include the Great Plains Region, where Lake Estes
could be another pilot site.
This study aims to apply the existing framework of reservoir sustainability planning and further development of
the guidelines to plan for and match the timing of sediment releases downstream of reservoirs to the inflowing
sediment concentrations at higher inflows are developed. Achieving a seasonally timed sediment balance through
a reservoir maintains reservoir capacity.reduces impacts to downstream aquatic species, and may even have
downstream benefits for rivers and aquatic species.
A sub-framework of environmental considerations for releasing reservoir sediment downstream will be developed
to guide future reservoir sustainability planning studies. This sub-framework could, for example, include a risk
matrix of easily applied factors, such as an inventory of sediment-dependent and sediment-averse aquatic
species, regime of flow releases, potential rates and concentrations of sediment releases with flushing/sluicing
relative to the inflowing sediment concentrations, downstream channel slope, and other factors.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Pilot Studies of Reservoir Sustainability Options - Flushing and Sluicing (final, PDF, 1.7MB)
By Caroline Ubing
Research Product completed on September 30, 2019

Reservoir Sustainability – Sediment Flushing (final, PDF, 922KB)
By Caroline Ubing
R&D Bulletin completed on September 30, 2019

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