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

2

BUILDING STRONG®

Required Flood Storage Capacity

3

BUILDING STRONG®

Spring Water Storage and Allocation

4

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

5

BUILDING STRONG®

Fish Conservation Refill and Guide Curve

6

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

7

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

8

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

9

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

10

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

BUILDING STRONG®

BUILDING STRONG®

BUILDING STRONG®

BUILDING STRONG®

BUILDING STRONG®

BUILDING STRONG®