2012 06-13 draft facilities planning report

DRA
AFT
FEAS
SIBILITY STUD & FA
Y DY ACILITIE PLA
ES ANNING REPO
G ORT
TOW OF YOUNTVIL
WN Y LLE RECY
YCLED W
WATER EX
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YOUN
NTVILLE, C
CALIFOR
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June 2
2012

Prepared for:
d

Mr. Graham Wadsworth PE
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Tow of Youn
wn ntville
6550 Yount S
Street
Yountv
ville, CA 94
4599

Prepared by:
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223 Mercury Way, Suite 150
35 e
Santa R
Rosa, CA 95
5407
(707) 523-1010

DRAFT
FEASIBILITY STUDY & FACILITIES PLANNING REPORT
TOWN OF YOUNTVILLE RECYCLED WATER EXPANSION PROJECT
YOUNTVILLE, CALIFORNIA

Project No. 12027-11001-37020

Prepared for:

Mr. Graham Wadsworth
Town of Yountville
6550 Yount Street
Yountville, CA 94599

Prepared by:

____________________________________

Reviewed by:

___________________________________

2235 Mercury Way, Suite 150
Santa Rosa, CA 95407
(707) 523-1010

June 2012

Contents

1. EXECUTIVE SUMMARY ................................................................................... 1
1.1 BENEFITS OF THE RECYCLED WATER PLAN...............................................................1
1.2 FACILITY PLANNING CONSIDERATIONS .......................................................................1
1.3 RECOMMENDED PROJECT .............................................................................................2

2. INTRODUCTION ............................................................................................... 3
2.1 BACKGROUND AND PROJECT PURPOSE.....................................................................3
2.2 STUDY AREA .....................................................................................................................4
2.3 PLANNING PROCESS .......................................................................................................4
2.3.1 WORKSHOPS AND PUBLIC OUTREACH ..................................................................... 4
2.4 DOCUMENT ORGANIZATION ..........................................................................................5

3. PROBLEMS AND NEEDS ................................................................................. 6
3.1 STUDY AREA CHARACTERISTICS .................................................................................6
3.1.1 HYDROLOGIC CHARACTERISTICS AND AMBIENT WATER QUALITY ...................... 6
3.1.2 LAND USE TRENDS AND POPULATION PROJECTIONS ............................................ 7
3.2 WATER SUPPLY ...............................................................................................................7
3.2.1 RECTOR RESERVOIR ................................................................................................... 7
3.2.2 STATE WATER PROJECT WATER SUPPLY................................................................. 8
3.2.3 GROUNDWATER ............................................................................................................ 8
3.2.4 RECYCLED WATER ....................................................................................................... 9
3.2.5 WATER DEMAND TRENDS............................................................................................ 9
3.2.6 SOURCES FOR ADDITIONAL WATER AND PLANS FOR NEW FACILITIES ............... 9
3.2.7 WATER SUPPLY AND DEMAND BALANCE .................................................................. 9
3.3 WASTEWATER TREATMENT & DISPOSAL ..................................................................10
3.3.1 EXISTING WATER RECYCLING AND EFFLUENT RIGHTS ........................................ 11
3.4 ENVIRONMENTAL WATER.............................................................................................11

4. WATER REUSE OPPORTUNITIES (MARKET ASSESSMENT) ..................... 12
4.1 IDENTIFICATION OF POTENTIAL CUSTOMERS ..........................................................12
4.2 DEMAND DEVELOPMENT ..............................................................................................14
4.3 SUMMARY OF MARKET ASSESSMENT RESULTS ......................................................18

5. PROJECT ALTERNATIVES ............................................................................ 19
5.1 ENGINEERING ANALYSIS FOR ALTERNATIVE COMPONENTS ................................19
5.1.1 RECYCLED WATER SUPPLY AND WATER BALANCE .............................................. 19

Town of Yountville GHD 12027-11001-32204
DRAFT Feasibility Study & Facilities Planning Report i June 2012

5.1.2 TREATMENT SYSTEM CAPACITY .............................................................................. 23
5.1.3 PUMPING AND DELIVERY RATE ................................................................................ 24
5.1.4 DISTRIBUTION SYSTEM CAPACITY ........................................................................... 24
5.2 COST ASSUMPTIONS ....................................................................................................25
5.3 ALTERNATIVE DESCRIPTIONS .....................................................................................26
5.3.1 ALTERNATIVE 1 – SERVE ALL TIER 2 CUSTOMERS ................................................ 26
5.3.2 ALTERNATIVE 1A – SERVE TIER 2 CUSTOMERS WEST OF THE NAPA
RIVER ............................................................................................................................ 27
5.3.3 ALTERNATIVE 2 – SERVE ALL TIER 2 CUSTOMERS AND IMPROVE
DELIVERY RATE TO TIER 1 CUSTOMERS................................................................. 29
5.3.4 ALTERNATIVE 2a – SERVE TIER 2 CUSTOMERS WEST OF THE NAPA
RIVER AND IMPROVE DELIVERY RATE TO TIER 1 CUSTOMERS........................... 30
5.3.5 ALTERNATIVE 3 – MAXIMUM BUILDOUT OF RECYCLED WATER SYSTEM
WITH LOOPED SYSTEM .............................................................................................. 32
5.3.6 ALTERNATIVE 3a – MAXIMUM BUILDOUT OF RECYCLED WATER SYSTEM
WITHOUT LOOPED SYSTEM ...................................................................................... 33
5.3.7 ALTERNATIVE 4 – CONSTRUCT A MINIMUM REUSE PROJECT ............................. 34
5.3.8 ALTERNATIVE 5 – CONSTRUCT AN URBAN WATER REUSE SYSTEM .................. 35
5.3.9 ALTERNATIVE 6 – CONSTRUCT A LAND DISPOSAL PROJECT .............................. 36
5.4 SUMMARY AND INITIAL SCREENING ...........................................................................37

6. ECONOMIC ANALYSIS OF ALTERNATIVES ................................................. 39
6.1 ALTERNATIVES TO RECYCLED WATER ......................................................................39
6.1.1 ADDITIONAL SWP SUPPLY ......................................................................................... 39
6.1.2 TOLERATE THE ECONOMIC IMPACTS OF DROUGHT ............................................. 39
6.2 COMPARISION OF ALTERNATIVES ..............................................................................40

7. RECOMMENDED PROJECT .......................................................................... 42
7.1 PROJECT DESCRIPTION ...............................................................................................42
7.1.1 BASIS FOR SELECTION .............................................................................................. 42
7.1.2 SELECTED CUSTOMERS AND USERS ...................................................................... 43
7.2 PROPOSED FACILITIES .................................................................................................43
7.2.1 FACILITIES DESCRIPTION .......................................................................................... 43
7.3 PROJECT IMPLEMENTATION ........................................................................................43
7.3.1 FEASIBILITY REPORT AND ENVIRONMENTAL DOCUMENTATION......................... 44
7.3.2 POLICY AND FUNDING ACTIVITIES ........................................................................... 45
7.3.3 CUSTOMER ACTIVITIES .............................................................................................. 46
7.3.4 PROJECT PERMITTING ACTIVITIES .......................................................................... 46
7.3.5 PROJECT DESIGN ACTIVITIES ................................................................................... 47

DRAFT Feasibility Study & Facilities Planning Report ii June 2012

Table Index
Table 1-1: Revenue Requirements and Unit Costs of Recycled Water ............................... 2
Table 2-1: Document Outline Requirements and Location of Information ........................... 5
Table 3-1: Water Supply and Demand Balance in the Study Area .................................... 10
Table 4-1: Tier 1 Users and Area Irrigated ........................................................................ 12
Table 4-2: Table 4-2: Tier 2 Users and Area Irrigated ....................................................... 13
Table 4-3: Tier 3 Users and Area Irrigated ........................................................................ 13
Table 4-4: Urban Customers ............................................................................................. 14
Table 4-5: Recycled Water Supplied to Tier 1 Users ......................................................... 15
Table 4-6: Average Monthly Percentage of Tier 1 Recycled Water Demand ................... 16
Table 4-7: Tier 2 and Tier 3 Irrigation Area and Demand by User ..................................... 16
Table 4-8: Urban Customer Irrigation Demand by User .................................................... 17
Table 4-9: Market Assessment Summary .......................................................................... 18
Table 5-1: Average Monthly Recycled Water Production Rates (MGD) ............................ 20
Table 5-2: NOAA Rainfall Data – Napa, California ............................................................ 21
Table 5-3: WRCC Evaporation Data – Berryessa Station ................................................. 21
Table 5-4: Pond Volume and Working Storage by Tier ..................................................... 23
Table 5-5: Distribution System Design Criteria .................................................................. 24
Table 5-6: Costs Included within Major CSI Divisions ....................................................... 25
Table 5-7: Average Annual Recycled Water O&M Costs .................................................. 26
Table 5-8: Summary Construction Cost Estimate for Alternative 1 .................................... 27
Table 5-9: Summary Construction Cost Estimate for Alternative 1a .................................. 28
Table 5-10: Summary Construction Cost Estimate for Alternative 2 .................................. 30
Table 5-11: Summary Construction Cost Estimate for Alternative 2a ................................ 31
Table 5-13: Summary Construction Cost Estimate for Alternative 3a ................................ 34
Table 5-17: Initial Alternative Screening ............................................................................ 38
Table 6-1: Economic Consequences Drought ................................................................... 40
Table 6-2: Summary Economic Comparison .................................................................... 41

Figure Index
Figure 2-1: Study Area
Figure 3-1: Study Area
Figure 4-1 Recycled Water Customers

DRAFT Feasibility Study & Facilities Planning Report iii June 2012

Figure 5-1: Alternative 1
Figure 5-1a: Alternative 1a
Figure 5-2 Alternative 2

Appendices
A Water Balances
B Cost Estimates
C Environmental Document
D Rate Study
E Recycled Water Use Ordinance
F Existing User Agreements

DRAFT Feasibility Study & Facilities Planning Report iv June 2012

1. EXECUTIVE SUMMARY
The Town of Yountville has, with the assistance of a State Water Resources Control Board planning grant
and a United States Bureau of Reclamation Feasibility and Environmental Studies cooperative
agreement, prepared a Feasibility Study and Facilities Planning Report (Report) for the Town of Yountville
Recycled Water Expansion Project (Project). The Project expands upon the existing recycled water
system to include new users which will maximize the recycled water supply delivered to current/future
customers, minimize discharges to the Napa River and establish a flexible system for connecting new
customers.

The Report:
 presents background water and wastewater information relating to the Town
 provides detailed planning criteria for the required recycled water facilities

 provides a market assessment of potential users
 evaluates several alternatives for providing recycled water to customers
 develops and analyzes the construction and operating costs for the alternatives, and

 presents a financing and revenue plan and preliminary construction schedule for the
recommended project.

1.1 BENEFITS OF THE RECYCLED WATER PLAN
If implemented, the Project will create multiple benefits including:
 reducing the water that would otherwise be withdrawn from the groundwater or Napa River for
vineyard use by the proposed customers.
 providing an effective means of disposing of excess wastewater that is already treated to a high
level.

 promoting the State’s policies of recycling water to supplement existing water supplies,
maximizing reuse of wastewater for beneficial uses, and discontinuing the use of potable water
and well water for irrigations when recycled water is available.

1.2 FACILITY PLANNING CONSIDERATIONS
In addition to the technical considerations of facility planning (ie flows, pressure, peaking factors),
consideration must also be given to the costs of the recycled water system and the resulting rates for the
recycled water users. Thus alternative systems with the ability to deliver different volumes of recycled
water for varying number of potential customers were considered and analyzed.

Below summarizes the parameters for alternatives reviewed which were retained for this study. The Town
has selected Alternative 1a as the preferred alternative.

Feasibility Study & Facilities Planning Report 1 June 2012

Table 1-1: Revenue Requirements and Unit Costs of Recycled Water

Alternative 1a Alternative 2a Alternative 3a

Capital Costs ($1,000) $2,722 $4,318 $11,200

Annual Operation and Maintenance $54,100 $54,100 $54,100

Water Delivered (AF) 179 179 335

Cost Per AF Delivered $15,210 $23,480 $34,430

1.3 RECOMMENDED PROJECT
Alternative 1a, the recommended project, results in the lowest unit cost and it provides a benefit in
reducing water withdrawal from groundwater, consistent with the State Water Resources Control Board’s
policies. This alternative provides for expansion of the recycled system and reduces discharges to the
Napa River.
Alternative 1a was selected as the recommended project for the following reasons:
 It achieves reduction in ground water and Napa River water use by the vineyards during the
irrigation season
 It utilizes existing storage ponds on the future recycled water users’ property
 It results in compliance with the Joint Wastewater Treatment Plant discharge flow limitations

 It provides for an effective cost per acre foot of recycled water compared to other alternatives
evaluated
 It provides a benefit to all water users
 It minimizes environmental impacts.


2. INTRODUCTION
This report, prepared in coordination with the Bay Area Recycled Water Coalition, presents an
engineering evaluation and an economic and financial analysis of a proposed expansion of the Town of
Yountville’s (Town’s) recycled water system.
The report is intended to fulfill the requirements of the U. S. Department of the Interior’s Bureau of
Reclamation Public Law 102-575, Title XVI (the Reclamation Wastewater and Groundwater Study and
Facilities Act of 1992, as amended) and the requirements of the State Water Resources Control Board’s
Planning Grant Program. Title XVI provides a mechanism for Federal participation and cost-sharing in
approved recycled water projects and provides general authority for appraisal and feasibility studies. The
State Water Board’s planning grant program also funds feasibility level studies and assists applicants in
developing the application materials necessary to qualify for other financial assistance programs
administered by the State Water Board.

2.1 BACKGROUND AND PROJECT PURPOSE
The Town currently delivers tertiary treated recycled water to a golf course and 770 acres of vineyards.
The Town produces approximately 450 acre-feet (AF) of recycled water annually and delivers
approximately 275 AF to customers. In an effort to balance both demands on the local water supplies and
to reduce seasonal discharges to the Napa River, the Town is developing a recycled water expansion
project that will reuse more of its high quality effluent.
Funded by planning grants from the U. S. Bureau of Reclamation (Bureau) and the State Water
Resources Control Board (State Board), the Town’s work includes developing a range of project
alternatives which have the potential to contribute to the resolution of several regionally-based, watershed
specific management problems.

The project area is tributary to the Napa River which supports a number of endangered species and is on
the State Board’s list of “impaired water bodies” for sediment, pathogens and nutrients. Restoration of the
Napa River is the subject of the award-winning Napa River Plan. Both wastewater discharges and
agricultural diversions can negatively impact the habitat of the Napa River. Pumping irrigation water from
groundwater aquifers also reduces the flow of water in the Napa River. An expanded recycled water
system will reduce discharge and provide an alternative water supply. This is consistent with the Napa
River Plan and the Regional Water Quality Control Board’s Basin Plan.
While the Town draws its primary water supply from local, state-operated Rector Reservoir, it can
supplement this supply with State Water Project (SWP) water. The operation of the SWP and its impact
on the Sacramento-San Joaquin Delta is arguably the largest regional water management problem facing
California today. An expanded recycled water project could lessen dependence on imported water.
Finally, the groundwater in the Napa Valley is a very valuable and increasingly taxed resource. Some of
the Town’s recycled water customers do not have any irrigation water source besides the recycled water.
The 2050 Napa Valley Water Resources Study (Napa 2050 Study) recognizes that expanded water
recycling within the Napa Valley would provide an alternative water supply and reduce demands on the
local groundwater basin. Recycled water is also a more sustainable and reliable source of water than the
local surface water, which is affected by droughts.


The Town operates a small utility system with a limited rate base of 800 customers and its efforts to
responsibly contribute to regionally-based watershed management problems must be developed in the
context of being affordable and manageable in the rural context. Specifically the Town has analyzed
alternatives for expanding the recycled water system in order to:
 Maximize the recycled water supply delivered to current/future customers
 Minimize discharges to the Napa River
 Establish a flexible system for connecting new customers.

2.2 STUDY AREA
The project study area, illustrated in Figure 2-1, was developed to evaluate opportunities for expanding
recycled water use within the Town and portions of Napa County which adjoin the Town. The study area
includes properties that are reasonably proximate to the Town’s existing infrastructure and includes a
number of properties that have existing, onsite seasonal water storage ponds, which can be used to
balance recycled water supplies with potential demands.

2.3 PLANNING PROCESS

2.3.1 WORKSHOPS AND PUBLIC OUTREACH
On August 26, 2011 the Town conducted a workshop with existing and potential recycled water users. At
the workshop, the Town provided an overview of:
 The recycled water program including drivers for the program and current customers
 Recycled water quality and allowable uses
 The proposed expansion project including the need for storage and benefits of offsetting
groundwater use
Customers expressed a general understanding of the benefits of an expanded program and requested
additional information on costs.
On March 23, 2012 the Town conducted a second workshop describing alternatives, financing methods
and potential costs shares. The Town provided and overview of:
 The history and purpose of the recycled water system
 The recommended project scope and benefits
 The existing rate structure
 The proposed future rate structure
The new customers mentioned they would only realize the benefit of a reliable water supply from the
project for water during the period from June 1 through October 31. Based on this feedback, the Town
recognizes the need to structure future recycled water contracts, for existing and new customers, to
provide the opportunity for all customers to receive some water during the summer months while still
maximizing the use of existing seasonal storage ponds.
The existing and potential customers seemed agreeable to the project.


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Legend

Study Area

Town Limits

Parcel Boundary

Existing Customers
Figure 2-1 Study Area

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2.4 DOCUMENT ORGANIZATION
This document has been organized to facilitate review under both the Bureau and the State Board’s
planning grant programs. Table 2-1 outlines those requirements and illustrates where they can be found
in this document.

Table 2-1: Document Outline Requirements and Location of Information

Reports Table of Contents Feasibility Report (Bureau) Facilities Plan/Project Report
(State Board)
1. Executive Summary Executive Summary
2. Introduction Introduction
3. Problem and Needs Problems and Needs Study Area Characteristics
Research Needs Water Supply Characteristics and
Facilities
Wastewater Characteristics and
Facilities
Treatment Requirements for
Discharged and Reuse
4. Water Reuse Opportunities Water Reuse Opportunities Recycled Water Market
(Market Assessment)
5. Project Alternatives Description of Alternatives Project Alternative Analysis
6. Economic Analysis Economic Analysis of Project Alternative Analysis
Alternatives

7. Recommended Project Legal and Institutional Recommended Facilities Project
Requirements Plan
Construction Financing Plan and
Revenue Program
Appendix A – Water Balances

Appendix B – Cost Estimates
Appendix C – Environmental Environmental Analysis of
Document Alternatives
Appendix D – Rate Study Financial Capability of the Rate Study
Sponsor Construction Financing Plan and
Revenue Program
Appendix E – Recycled Water Recycled Water Use Ordinance
Use Ordinance

Appendix F –Existing User Existing User Agreements
Agreements


3. PROBLEMS AND NEEDS
The Town has undertaken this study because it recognizes the need to optimize the use of its water
resources. The first part of this section provides a general overview of the study area including the local
hydrologic characteristics and water quality and land use and population trends. The second part of this
section provides detail on water supplies and demands and future water supply projects that may be
necessary to meet these demands. The third part provides a similar detail on the wastewater treatment
and disposal systems. An expanded recycled water system has the potential to meet water demands,
resolve disposal challenges and support both the economy and the ecology of the study area.

Like many agencies, the Town describes its water supply and water demands in terms of acre-feet (AF)
and its wastewater flows and wastewater capacity in terms of million gallons (MG). There are
approximately 3 AF in 1 MG.

3.1 STUDY AREA CHARACTERISTICS
The project study area, shown in Figure 3-1 is in the central part of the Napa Valley and includes the
Town’s incorporated area, the California Veterans Home, and unincorporated vineyards proximate to the
Town’s existing recycled water infrastructure. The study area is located in one of the most renowned
vinticultural regions in the world and the study area includes significant agricultural land along with urban
uses that support a tourist industry.
The study area is 8 miles north of the City of Napa, 9.5 miles south of the City of St. Helena and straddles
both sides of the Napa River.

3.1.1 HYDROLOGIC CHARACTERISTICS AND AMBIENT WATER QUALITY
As illustrated in Figure 3-1, the study area is located in the watershed of the Napa River, over the Napa
Valley groundwater basin and in the North Bay portion of the San Francisco Bay Hydrologic Region. The
study area is characterized by a Mediterranean climate with warm dry summers and wet cool winters.
Rain generally occurs between October and May. January and February are usually the wettest months.
The Town’s primary water supply is drawn from Rector Reservoir on Rector Creek, a tributary to the Napa
River. The Napa River is tributary to the San Pablo Bay estuary, whose remaining tidal wetlands serve in
a vital ecological role as nurseries for fisheries and wintering areas for migratory waterbirds. The Basin
Plan for the San Francisco Bay Region lists the beneficial uses of the Napa River as:
 Agricultural & municipal water supply
 Habitat for cold and warm water species
 Habitat for rare species
 Spawning habitat
 Wildlife use
 Recreation use
 Navigation use
The Napa River is listed on the State Water Board’s 2006 303(d) impaired water bodies list as impaired
for nutrients, pathogens and sedimentation and siltation. The Napa County Flood Control and Water


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Town Limits Tier 1 Service Area Existing 6-inch Pipe 0 900 1,800 ft Figure 3-1
www.ghd.com Study Area
Parcel Boundary Tier 2 Service Area 1 inch = 1,800 feet printed at 8.5x11
Recycled Water
Ponds Tier 3 Service Area Sources: ESRI Basemap: Aerial; Napa
County GIS: Parcels, City Limits,
Project
Cartography Date Project #
Roads; Winzler and Kelly GIS: Study
Streams and Rivers Area, RW Pipes, Tiers. AF 5/31/2012 1202711001 Town of Yountville

Conservation District has partnered with the Army Corps of Engineers on an ambitious multi-year
restoration program that intended to enhance beneficial uses, improve water quality and reduce flooding.
The Town’s recycled water program generally supports beneficial uses of the river and restoration of
ecological function through the reduction of discharges to the River.

3.1.2 LAND USE TRENDS AND POPULATION PROJECTIONS
As illustrated in Figure 3-1 the study area includes significant agricultural development surrounding the
compact urban development within the Town and the Veterans Home. There is very little “undeveloped”
property within the study area.
Existing agricultural uses are protected as Agricultural Resource lands in the Napa County Land Use
Plan. The Town, which was incorporated in 1965, is generally described as “built out”. The Town has a
population of 2,900, of which 1,000 reside in the Veterans Home of California. Because of its reputation
as a high quality visitor’s destination, the Town has experienced pressure for expansion but has adopted
policies to restrict development to modest expansion of local-serving businesses.

3.2 WATER SUPPLY
The Town has defined a study area that includes its municipal boundaries, the California Department of
Veterans Affairs Yountville Veteran’s Home and approximately 4,000 acres of vineyards within a five mile
radius of its existing recycled water pipelines. The study area has four principal sources of water, besides
recycled water. These include:
 Rector Reservoir which provides primary water supply to the Town and the Veteran’s Home and
which is owned and operated by the State of California
 Groundwater which provides backup municipal water supply, irrigation water supply and frost
protection of planted vines
 Napa River which provides irrigation water supply and frost protection of planted vines
 The North Bay Aqueduct, which is owned and operated by the California Department of Water
Resources, and can deliver State Water Project (SWP) supplies through an agreement with Napa
County Flood Control and Water Conservation District (District) to the Town under certain types
of emergency conditions

3.2.1 RECTOR RESERVOIR
The Town’s principal water supply is Rector Reservoir on Rector Creek, This facility, which is owned and
operated by the State of California, delivers local surface water to the California Veteran’s Home and the
Town for municipal supply and to the Department of Fish & Game (DFG) for environmental uses and a
fish hatchery.
There have been several studies of Rector Reservoir’s capacity and safe yield. The most recent technical
study by the California Department of Water Resources (DWR) in 2000 calculated the reservoir capacity
to be 4,535 acre-feet. The safe yield was estimated to be 1,670 acre feet annually (AFA) based on actual
deliveries during the 1992 drought including 1,190 AFA in flow releases needed to meet DFG’s in-stream
flow requirements. The Town’s contractual capacity allowance in Rector Reservoir is 500 AF per year.


Based on safe yield reliability analyses developed by the California Department of Water Resources
(DWR), this supply is estimated to be reduced to 125 AF per year in dry years.

3.2.2 STATE WATER PROJECT WATER SUPPLY
The Napa County Flood Control and Water Conservations District (District) administers the SWP contract
for municipalities in Napa County. Surface water is delivered by the SWP through the North Bay Aqueduct
(NBA), treated at the City of Napa’s Jameson Canyon water treatment plant and delivered to Yountville
through the Conn transmission main.
The Town had historically held an entitlement for a total SWP contractual amount of 1,100 AF per year.
Upon completion of its municipal well, the Town entered into an agreement with the District to sell this
entitlement but retain an emergency supply of 25 AF per year (intended to provide fire or short-term
supply) and the right to be included in the District’s dry-year water bank negotiations for an amount up to
200 AF. The Town is not guaranteed that it will receive the 200 AF and is obligated to pay market price for
the water at the time it is secured.

3.2.3 GROUNDWATER
The Town overlies the Napa Valley groundwater subbasin, which provides municipal and agricultural
water supply in the area. The groundwater level data illustrates generally stable long term trends in the
St. Helena, Yountville, and Napa areas. Groundwater quality is generally good, with some selected areas
of elevated constituents, along the Napa valley floor of elevated nitrates. The Town has developed a
groundwater supply system which is anticipated to yield 300 AF annually and which is generally used as a
backup to the Rector Reservoir supply.
In 2005 the District, as part of its water supply functions, developed the 2050 Napa Valley Water
Resources Study (Napa 2050 Study) which reviewed the water supply and demand balances for
municipal and agricultural uses in Napa County. The Napa 2050 Study projected that the safe yield of
Napa Valley groundwater sub-basin is 28,000 AF. The Napa 2050 Study indicates that basin demands
could exceed supply during dry years by 6,000 AF in 2020 and 10,000 AF in 2050.

For preliminary planning purposes, the Town estimated that the study area, which covers approximately
10-percent of the groundwater basin area, could experience shortages of 600 to 1,000 AF (10-percent of
the total basin shortages). Complicating this simple estimate of potential shortage is the fact that the
groundwater supply is subject to geographic variability. Generally, groundwater is available west of the
Napa River but much scarcer east of the Napa River.
Importantly for the Town and agricultural water users around the Town, the Napa 2050 Study highlights
that the groundwater resource may be unable to meet the full range of demands placed upon it, during
dry periods in the relatively near future.

3.2.3.1 Groundwater Management
There are three basic methods available for managing groundwater resources in California:
 management by local agencies under authority granted in the California Water Code or other
applicable State statutes,
 local government groundwater ordinances or joint powers agreements, and
 court adjudications.


2012 06-13 draft facilities planning report

2012 06-13 draft facilities planning report

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