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Pacheco Reservoir Expansion ProjectPresented by: Christopher Hakes, Deputy, Dam Safety and Capital Delivery Division

Unique Opportunity for Ecosystem Enhancement, Flood Risk Reduction, Improved Water Supply Reliability and Emergency Water Supply

San Luis & Delta-Mendota Water AuthorityJuly 11, 2019

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3Project Partners

Pacheco

Pass Water

District

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4San Luis Reservoir

Existing

Pacheco

Reservoir

Project Location

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Project Location

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Background

• B.F. Sisk Dam constructed between 1963 and 1967

• Owned by Reclamation and jointly operated with DWR

• San Felipe Division of the CVP constructed between 1964 and 1987

• The Pacheco Pumping Plant intake in the reservoir is located 38’ higher than the Gianelli Intake

• Algae induced water quality issues in late summer/early fall create water supply reliability issues for San Felipe Division Contractors

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San Luis Low Point Improvement Project

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San Luis Low Point Improvement Project

The San Luis Low Point Problem

• Supply interruptions occur when storage levels fall below 300 TAF

• Algae related issues in late summer/early fall can create water supply reliability issues for San Felipe Division Contractors

• Dead pool storage is at 79 TAF6

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San Luis Low Point Improvement Project

Alternatives Under Consideration• Lower Pacheco Intake

o Pipeline Optiono Tunnel Option

• Treatment Alternative• San Luis Reservoir Expansion Alternative• Pacheco Reservoir Expansion Alternative*

*Identified as the NED alternative and Locally Preferred Plan in the April 2019 SLLP Draft Feasibility Report

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San Luis Low Point Improvement Project

NED Calculation Summary

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Alternative Plan

Total Construction Cost (Million $)

2018 $

Annualized Benefits, 100 years, 2.75%

(Million $)

Annualized Costs, 100 years, 2.75% discount

rate (Million $)

Benefit-Cost Ratio

Lower San Felipe Intake (Tunnel) $962.0 $2.0 $26.3 0.1

Lower San Felipe Intake (Pipeline) $842.0 $2.0 $29.7 0.1

Treatment $44.0 $2.1 $2.2 0.95

San Luis Reservoir Expansion $830.0 $4.2 $22.5 0.2

Pacheco Reservoir Expansion $1,116.0 $34.8 $29.1 1.2

Existing Pacheco Reservoir Facilities

Existing Dam/Reservoir

• 5,500 acre-foot reservoir

• 100-foot-tall earth embankment dam

• Concrete spillway

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Existing North Fork Dam – Pacheco Reservoir

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Existing Concrete Spillway

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Proposed Pacheco Reservoir Facilities

Expanded Dam/Reservoir• Up to 140,000 acre-foot

reservoir• New 319-foot earth

embankment dam• New concrete spillway

Conveyance between Pacheco Conduit and expanded reservoir

• 1-Mile tunnel/pipeline• Pump station• Selective level inlet/outlet

structure within reservoir

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Existing & Proposed Dam Storage Capacity

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Before After

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Existing & Proposed Dam Rendering

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Project Benefits to San Luis & Delta-Mendota Water

Authority

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• Up to 200,000 AF additional space in San Luis Reservoir (SLR) during low point events

• Potential to generate additional capacity for rescheduled water in SLR• Increased water supply reliability South of Delta• Diversified storage allows flexibility during emergencies• Facilitates potential exchanges and transfers South of Delta for

project participants and South of Delta agencies• Funded by CWC, SCVWD, SBCWD, and project partners*

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Additional Project Benefits

Enhance habitat for federally threatened steelhead

Enhance water supply in below- normal years to wildlife refuges in the Delta

Increase water supply reliability and emergency water supply

Resolve the water quality problem in supply sourced from San Luis Reservoir

Reduce flooding along Pacheco Creek and to disadvantaged communities

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Enables Federally Threatened Steelhead Recovery

The Project will improve habitat critical to recovery• Provides water flow in Pacheco Creek

when fish needs the most

• Larger cold water pool means cooler water in summer and fall when temperatures are high

• Enables growth of an independent population in the Pajaro River watershed, which improves survival potential of the SCC steelhead.

Enhances Bay-Delta Ecosystem

Increases water supplies to DeltaWatershed refuges• Dedicates irrigation to wetlands

in below-normal water years

• Increases food supply for migrating Pacific Flyway waterfowl in the fall and winter

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Enhances Water Supply for Agriculture and M&I

The Project will reduce drought risk to agricultural and M&I water users• Increases the water supply in dry

years

• Improves groundwater conditions to agricultural customers

• Materially contributes to sustainable groundwater management goals in four basins

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Provides Emergency Water Supply

The Project will provide dedicated emergency water supply• Increases emergency water

supply

• Increases local surface storage capacity by 90%

• Mitigates risk of Delta export outages and imported water conveyance outages

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Eliminates San Luis Low Point Water Quality Issues

The Project reduces operational constraints at San Luis Reservoir and prevents impaired water quality deliveries by• Delivering CVP supplies to the

Pacheco Reservoir earlier in the season

• Providing Pacheco Watershed supplies captured in expanded reservoir

• Using the Pacheco Reservoir as a blending source when needed

• Reducing spikes in taste and odor

Algae Bloom

in San Luis

Reservoir

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Reduces Flooding in Disadvantaged Communities

The Project will protect disadvantaged and vulnerable communities against flooding• Decreases flood flows by up to 61%

downstream of dam by reducing Pacheco reservoir releases

• Reduces 100-year flood flows by up to 4,7000 cfs

• Prevents floods equivalent to January 11 and February 10, 2017 Pacheco Creek floods

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Project Schedule

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August 2017

WSIP application submitted to commission

July 2018

Commission conditional approval of $484.55 M /

$24.2 M early funding

July 2019

Nov 2018

Commenced Planning and

Design

Jan 2022

Draft EIR for public review

April 2024

Finalize Plans and

Specifications

Nov 2024

Award Construction

Contract

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Pacheco Reservoir Expansion Proposed Project: 1 minute, 13 secondshttps://www.youtube.com/watch?v=HdWYxYnWO_8&feature=youtu.be

Pacheco Reservoir Expansion Project: Fisheries Benefits: 3 minutes, 54 seconds https://www.youtube.com/watch?v=wN3_8CKWO5s&feature=youtu.be

Pacheco Reservoir Expansion Project: 2 minutes, 1 second https://www.youtube.com/watch?v=fu8th08j5QQ&feature=youtu.be