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US Army Corps of Engineers
BUILDING STRONG®
US Army Corps of Engineers
BUILDING STRONG®
HOWARD A. HANSON DAM
Water Management
Scott Pozarycki
20 June 2018
BUILDING STRONG®
Purposes
Flood Risk Reduction is primary mission► 104,000 acre-feet of authorized flood storage
Fish Conservation Authority► 24k ac-ft, 1962
Section 1135 ecosystem restoration project► 5k ac-ft; 1997; absorbed into AWSP in 2000
Tacoma municipal and industrial (AWSP)► 20k ac-ft; 2007
Other elements► Tacoma water rights► Tacoma HCP► Tacoma – MIT 1995 agreement
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BUILDING STRONG®
Required Flood Storage Capacity
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BUILDING STRONG®
Spring Water Storage and Allocation
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BUILDING STRONG®
Fish Conservation
Goal: maintain minimum of 110 cfs at the
Palmer stream gage (95% reliability)
►Requires capture and storage of 24,000 ac-ft
►Water released/conserved based on guide
curve to ensure above goal
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BUILDING STRONG®
Fish Conservation Refill and Guide Curve
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BUILDING STRONG®
Section 1135 Ecosystem Restoration
Objectives: ► Capture 5,000 ac-ft during spring refill
► Release water to ensure maximum benefit
► Decisions made by Corps with input from the Green
River Flow Management Coordination Committee
Adaptive management alternative► Storage and release adaptively managed based on
annual hydrology, natural resources, regulatory
considerations, etc.
► Project sponsor is Tacoma
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BUILDING STRONG®
Tacoma M&I
Additional Water Storage Project (Phase 1)
►Corps captures and stores 20,000 ac-ft for
Tacoma use
►Tacoma determines release schedule
►First captured and stored in 2007
►Not yet fully implemented
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BUILDING STRONG®
Spring Refill Objectives
Adaptively store water for all purposes
minimizing impacts to natural resources
Capture objective is 49,000 ac-ft
►24,000 ac-ft fish conservation
►5,000 ac-ft section 1135
►20,000 ac-ft Tacoma
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BUILDING STRONG®
Typical Augmentation Objectives
Ensure instream minimum flows
►110 cf at Palmer (Corps objective)
►250 cfs at Auburn (GRFMCC objective)
Minimize steelhead redd dewatering
Maximize summer rearing habitat
Support Chinook salmon adult migration
and spawning
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BUILDING STRONG®
Green River Flow Management
Coordination Committee
Biweekly conference calls during the refill and
augmentation period (late Feb to Nov)
Any agency/individual can participate
Discussion of environment & resource
conditions, water supply, water needs
Develop capture & release strategy;
Provides recommendation to Corps - goal is to
achieve consensus on path forward11
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