UNDERSTANDING THE DELTA AN ENGINEERING PERSPECTIVE

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UNDERSTANDING THE DELTA - AN ENGINEERING
PERSPECTIVE
Richard A. Denton Water Resources Manager Contra
Costa Water District
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Location of Delta and Relationship to CALFED
Bay-Delta Program Solution Area
Sacramento
Sacramento River
Suisun Marsh
Geographic Scope of Problem Identification

San Joaquin River
Stockton
Geographic Scope of
Solution
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Major CaliforniaRivers
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Water Projectsand Major Riversin California
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Importance of the Delta

• Source of Drinking Water for 22 Million People
• 750 Plant Animal Species
• Supports 27 billion Agricultural Industry
• Local Homes and Infrastructure
• 80 of the States Commercial Salmon Fisheries
• Californias Trillion Dollar Economy

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Sacramento
Vallejo, Solano
Delta Outflow
CCWD - three intakes
San Joaquin
SWP and CVP Exports
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Contra Costa Water District
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Contributions to Delta Outflow(Annual Average
28 Million Acre-Feet)
Data Source DWR Delta Atlas
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DELTA GOALS

• Ensure good water quality for fish, for drinking
  water, agriculture and other beneficial uses
• Restore sustainable ecosystem and improve aquatic
  and terrestrial habitats
• Reduce mismatch between water supply and demand
• Improve structural integrity of Delta levee
  system and other facilities
• Based on CALFED Bay-Delta Program Goals

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ENGINEERING APPROACHES FOR ACHIEVING GOALS

• Barriers/Tide Gates
• Water quality
• Fish
• Water levels
• Increased Flows
• San Joaquin River Recirculation Study
• Fish Screens and Fish Salvage
• New or Improved Conveyance
• Increased pumping capacity
• New or expanded storage
• Groundwater conjunctive use
• Off-stream or on-stream surface storage
• In-Delta storage

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Yellow diamonds represent dams in California
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SOFT PATH PROPOSALS FOR ACHIEVING GOALS

• Watershed Protection and Source Control
• Advanced Drinking Water Treatment
• Ultraviolet Disinfection
• Membranes
• Improved Water Use Efficiency
• Conservation
• Reclamation
• Water Transfers
• Removal of Barriers to Fish Migration
• Dam removal on smaller tributaries
• Wetland and Riparian Habitat Restoration

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Barriers/Tide Gates

• Delta Cross-Channel Gates
• Water Quality
• Fish
• South Delta Improvement Program
• Water Levels (for farmers)
• Fish (Head of Old River Barrier)
• Improved circulation for water quality

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Georgiana Slough
DCC
Sacramento River
Sacramento River
Delta Cross Channel and Georgiana Slough
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Delta Cross-Channel

• Operated by U.S. Bureau of Reclamation
• Designed to increase flow of fresh Sacramento
  water into Central Delta (water quality)
• Closed at high flows to avoid Delta flooding
• May cause out-migrating salmon to stray
• Closed Nov-Jan (up to 45 days) and May-June (14
  days) (fish)
• Oct-Nov 1999 closure for fish caused Delta water
  quality standards to be violated

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1999 Cross-Channel Closure
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CALFED Cross-Channel Experiments

• Goal is to protect fish as they move downstream
  without degrading Delta water quality
• What is effect of only closing gates only on ebb
  tide (when flow and fish moving downstream)?
• No impact on water quality
• Do fish move during day or at night?
• What is effect of only leaving gate open one
  flood tide per day (i.e., 6 hours)?
• Some impact on water quality

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CALFED South Delta Improvement Program

• Head of Old River barrier for fish
• Three operable barriers for agricultural water
  levels and quality
• Maintains water levels in channels for South
  Delta farmers (eastern side of barriers)
• Creates some circulation for water quality for
  farmers
• New fish screens for CVP and SWP export pumps
• Channel dredging
• Increased SWP export pumping
• Agricultural drainage reduction near CCWD intakes

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Redirected Water Quality Impacts
Rock Slough Intake (CCWD)
Poor Quality San Joaquin Inflow
Old River Intake (CCWD)
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Proposals for Conveying Water Through or Around
the Delta

• Peripheral Canal (1982)
• Through Delta - channel widening
• Chain of Lakes
• CALFED Modified Through-Delta Alternative
• Towing water bags

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Peripheral Canal Isolated conveyance around the
Delta 29,000 cfs capacity
Hood
Export Pumps
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Sacramento River
Through Delta Alternative Inundated
Islands Setback Levees
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CALFED THROUGH-DELTA CONVEYANCE
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CentralDeltaIntakeConcept(not carried
forward)
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New or Expanded Storage Proposals

• Los Vaqueros Expansion (add 400 TAF)
• Raise Shasta Dam (add 300 TAF)
• In-Delta Storage (250 TAF)
• Sites Reservoir near Willows (1.9 MAF)
• Expanded San Joaquin reservoir storage, e.g.,
  Friant (add 250-700 TAF)
• Groundwater storage (500 TAF - 1 MAF)

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Los Vaqueros Reservoir Contra Costa Water
District
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CCWD LOS VAQUEROS PROJECT

• 100,000 acre-feet off-stream reservoir for water
  quality and emergency water supply
• New 250 cfs screened diversion off Old River
• Blending water released from Los Vaqueros when
  needed to meet 65 mg/L delivered goal
• Provides ecosystem benefits because
• CCWD takes water from reservoir during low flow
  periods (water quality)
• CCWD ceases diverting from Delta for 30 days in
  spring (fish protection)

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CCWD LOS VAQUEROS PROJECT

• 1987 -- Project planning and design begins
• Sept. 1994 -- Construction of reservoir began
• Summer 1997 -- First diversions from new intake
• Jan. 1998 -- Reservoir construction completed
  (first reservoir completed in California in 10
  years)
• Jan. 1999 -- Reservoir full for first time
• July 1999 -- Los Vaqueros Project wins ASCE
  Outstanding Civil Engineering Achievement Award

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CALFED LOS VAQUEROS RESERVOIR EXPANSION STUDIES

• Identified in CALFED Record of Decision
• Would improve Bay-Area urban water quality and
  supply reliability
• Increase reservoir from 100 TAF up to 500 TAF.
• CCWD has contracted with DWR to perform studies
  of expansion.
• Closely coordinated with CALFED Bay Area
  Blending/Exchanges studies
• Physical interconnections between agencies.
• Sharing of high quality water supplies to enhance
  delivered water quality for Bay Area users.

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SWRCB Estuarine Habitat Standards

• Adopted by State Water Board in 1994
• Require 2 ppt salinity to be east of Roe Island,
  Chipps Island and Collinsville for a given number
  of days for the months of February through June
• Number of days at each location determined from
  runoff to Delta in previous month
• Number of days based on recreating flow
  conditions during 1968-1975
• Number of days developed from historical flow
  data using CCWDs salinity-outflow model

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Collinsville
Roe Island
Chipps Island
Los Vaqueros Reservoir
Export Pumps
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Salinity-Outflow Model
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Tidal Filling and Draining
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Salinity-Outflow Model
Actual Delta Outflow
Salinity at Chipps Island
Net Delta Outflow
Calculation of Suisun Bay Salinity based on
Present and Previous Outflows from Delta
Storage of Water within Delta because of 14-Day
Cycle of Mean Water Level
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Salinity-Outflow Model
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For More Information
CALFED Bay-Delta Program www.calfed.ca.gov Cal.
Department of Water Resources www.dwr.water.ca.gov
Contra Costa Water District www.ccwater.com
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CALFED PROGRAM AREAS

• Ecosystem Restoration
• Water Quality
• Governance
• Water Supply Reliability
• Watersheds
• Storage
• Conveyance
• Environmental Water Account
• Water Use Efficiency (conservation and recycling)
• Water Transfers
• Levees
• Science

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SUISUN MARSH SALINITY CONTROL GATES
Sacramento River
Suisun Marsh
Montezuma Slough Control Structure
Suisun Bay
San Joaquin River
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ENGINEERING TOOLS

• Hydrologic and reservoir operation models
• Hydrodynamic transport models
• Contaminant transport models, e.g., salt
  transport
• Statistical correlations
• salinity-outflow
• fish-flow
• Conceptual fish population models
• Fish transport models

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How the system is run

• Northern California Hydrology
• Wet year 4 months with rain, 8 dry
• Dry year 2 or 3 months with rain, 9 or 10 dry
• Critically dry 3 or 4 storms in a year
• Major water sources
• Sierra snowfall
• Basin rainfall
• Local rain and groundwater

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Tidal Influence

• Flows in Channels
• Tides up to 500,000 cubic feet per second
• Outflow typically 3,000 cfs to 100,000 cfs
• Tides and seawater intrusion
• Tides bring in seawater, river flows push it back
• Good water quality if outflow is 7,000 cfs or
  more
• Outflow is less than 5,000 cfs September through
  December