11.a. NCMA Annual ReportMEMORANDUM
TO: CITY COUNCIL
FROM: 4' TERESA McCLISH, COMMUNITY DEVELOPMENT DIRECTOR
SUBJECT: PRESENTATION OF THE 201 1 NORTHERN CITIES MANAGEMENT AREA
(NCMA) ANNUAL REPORT
DATE: MAY 22,201 2
RECOMMENDATION:
It is recommended that the City Council receive a presentation of the 201 1 Northern Cities
Management Area (NCMA) Annual Report.
IMPACT ON FINANCIAL AND STAFFING RESOURCES:
The cost to produce the 201 1 annual groundwater monitoring report was $1 19,922. The
cost is shared among several agencies, of which the City is responsible for 30.05%, or
$36,641. The contract was approved August 23,201 1 and the cost is paid from the Water
Fund. The work for the 201 1 report is complete. There is no fiscal impact for filing the
report with the court. Staff time is required for participating on the NCMA technical group.
Water resources are a priority in the Critical Needs Action Plan.
BACKGROUND:
The City, as a member of the NCMA Technical Group, has continued to participate with
neighboring jurisdictions on required reports and studies concerning the management of
the Santa Maria Groundwater Basin. Members of the NCMA include representatives from
jurisdictions that were part of the Santa Maria groundwater litigation (the City, Pismo
Beach, Grover Beach, and the Oceano Community Services District.) The 201 1 annual
report is the fourth such report that was submitted to the court in early May. For the last two
years, the City and other NCMA member agencies have contracted with Water Systems
Consultirrg (WSC) and GEI consultants to assist in the coordination and analysis of data
and joint management, and for the preparation of the annual report that is required in
accordance with the Santa Maria Groundwater Basin Adjudication.
ANALYSIS OF ISSUES:
In 2008, a water balance study of the groundwater basin indicated a need to implement a
monitoring and reporting program. The NCMA Technical Group meets monthly, working
together on data collection and operation needs in order to maintain the health of the
groundwater basin. The annual report outlines this progress and provides an evaluation on
the status of the groundwater basin that continues to be a healthy and sustainable water
supply for the City. WSC will present report findings and answer questions concerning the
condition of the groundwater basin.
Agenda Item 11.a.
Page 1
CITY COLlNClL
PRESENTATION OF THE 201 1 'THE NCMA ANNUAL MONITORING REPORT
MAY 22,2012
PAGE 2
ALTERNATIVES:
The following alternatives are provided for the Council's consideration:
Receive presentation of the 201 1 annual report;
ADVANTAGES:
Continuing to prepare and submit annual reports as required also helps to ensure the
implementation of the monitoring and reporting that provides a mechanism allowing all
parties to be better informed and efficiently react as necessary with regard to the changirlg
condition of the groundwater basin.
DISADVANTAGES:
No disadvantages have been identified.
ENVIRONMENTAL REVIEW:
No environmental review is required for this item.
PUBLIC NOTIFICATION AND COMMENTS:
The Agenda was posted in front of City Hall on Thursday, May 17,2012. The Agenda and
staff report were posted on the City's website on Friday, May 18, 2012. No public
comments were received.
~ttachment:
1. 201 1 Northern Cities Management Area Annual Report
Agenda Item 11.a.
Page 2
Final
2011 Annual Monitoring Report
Northern Cities
Management Area
Submitted to: The Northern Cities
hrlanagernent Area Technical Group
City ofhroyo Grande, City of Grover Beach, City of
Pismo Beach, and the Oceano Community Services
District, San Luis Obispo County, Cahfornia
Date: May 4,2012
Project No: 116660
Robert Amy, PG
Project Director
Agenda Item 11.a.
Page 3
ATTACHMENT 1
201 1 Annual Monitoring Report
for the
Northern Cities Management Area
May 201 2
'This report was prepared by the staff of GEI ConsulUits, Inc. under the supervision of professionals whose signatures appear hereon.
The findings or professional opinions were prepared in accordance with generally accepted professional engineering and geologic practice.
Robert Almy, PG /
Project Director
Samuel W. Schaefer, PE
Senior Engineer
Agenda Item 11.a.
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Table of Contents
1 - Introduction 1
2 - Climate Conditions 3
2.1 Precipitation 3
2.2 Evapotranspiration 4
3 - Water Demand 5
3.1 Urban Demand 5
3.2 Applied Irrigation Demand 6
3.3 Rural Demand 8
3.4 Changes in Water Demand 8
4 - Water Supplv Sources 9
4.1 Sources of Supply 9
4.1.1 Lopez Lake Supply 9
4.1.2 State Water Project 10
4.1.3 Groundwater 10
4.1.4 Developed Water I I
4.1.5 Water Use by Supply Source 12
4.2 Groundwater Conditions 13
4.2.1 Groundwater Monitoring Network 13
4.2.2 Groundwater Levels 14
4.2.3 Water Quality 16
4.3 Threats to Water Supply 30
4.3.1 Threats to State Water Project Supply 3 0
4.3.2 Seawater Intrusion 3 1
4.3.3 Measures to Avoid Seawater Intrusion 3 2
4.3.4 Change in Groundwater Recharge 3 2
5 - SupplyIDemand Comparison 34
6 - Mananement Activities
6.1 Management Objectives
6.1.1 Share Groundwater Resources and Manage Pumping.
6.1.2 Monitor Supply and Demand and Share Information
6.1.3 Manage Groundwater Levels and Prevent Seawater Intrusion
6.1.4 Protect Groundwater Quality
6.1.5 Encourage Water Conservation
6.1.6 Manage Cooperatively
6.1.7 Other Potential Management Objectives
6.2 Update on Management Activities
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6.2.1 Expansion of Groundwater Monitoring 42
6.2.2 Control of Groundwater Levels and Seawater Intrusion 42
6.2.3 Cooperative Water Supply Planning and Management 42
6.2.4 Water Conservation 43
6.2.5 Alternative Water Supply Studies 46
7 - References Cited 48
Table 1
Table 2
Table 3
Table 4
Table 5
Table 6a
Table 6b
Table 7
Total Demand for Groundwater and Surface Water, AFY
Gross lrrigation Requirement for WPA 5 by Crop Group
Estimated Rural Water Demand
Zone 3 Contractor Water Entitlement (AFY)
Available Urban Water Supplies, AFY
Northern Cities Sentry Well Water Quality Data Summary
Northern Cities Sentry Well Water Quality Data Summary
201 1 Water Demand by Source (AF)
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9A
Figure 9B
Figure 10
Figure 11
Figure 12A
Figure 12B
Figure 12C
Figure 12D
Figure 12E
Figure 13
Figure 14
Figure 15
Santa Maria River Valley Groundwater Basin
Northern Cities Management Area
Annual Precipitation 1950 to 20 1 1
Monthly 201 1 and Average Precipitation and Evapotranspiration
Municipal Water Use by Source
Total Water Use by Source
Location of Sentry Wells
Depths of Sentry Wells
Groundwater Elevation Contours Spring 20 1 1
Groundwater Elevation Contours Fall 201 1
Selected Well Hydrographs
Sentry Well Hydrographs
Hydrograph of Average Deep Sentry Well Elevations
Water Elevation, Conductivity, and Temperature, Well 24B01
Water Elevation, Conductivity, and Temperature, Well 24B03
Water Elevation, Conductivity, and Temperature, Well 30F03
Water Elevation, Conductivity, and Temperature, Well 30N02
Chloride Concentrations over Time in Sentry Wells
Total Dissolved Solids Concentrations over Time in Sentry Wells
Schoeller Diagram for Sentry Well 30N02, 2010-2012
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1 Introduction
This report summarizes hydrologic conditions in the Northern Cities Management Area
(NCMA) of the Santa Maria Groundwater Basin in San Luis Obispo County (County),
California on behalf of four public agencies, specifically the City of Arroyo Grande (Arroyo
Grande), City of Grover Beach (Grover Beach), City of Pismo Beach (Pismo Beach) and the
Oceano Community Services District (Oceano CSD), (Northern Cities). These agencies,
along with local land owners, the County of San Luis Obispo (County), and the San Luis
Obispo County Flood Control & Water Conservation District (FC&WCD) have managed
local surface water and groundwater resources since the late 1970s to preserve the long-term
integrity of water supplies.
This longstanding approach was formalized in the 2002 Settlement Agreement among the
Northern Cities, Northern Landowners, and Other Parties, and incorporated in the 2005
Settlement Stipulation for the Santa Maria Groundwater Basin Adjudication (Stipulation).
The June 30,2005 Stipulation was agreed upon by numerous parties, including the Northern
Cities. The approach was then adopted by the Superior Court of California, County of Santa
Clara, in its Judgment Afer Trial, entered January 25,2008 (Judgment). Figure 1 shows the
four Northern Cities relative to the Santa Maria Valley groundwater basin, as defined in the
adjudication and the Santa Maria River Valley groundwater basin (Basin 3-12) as defined by
the Department of Water Resources @WR).
The Judgment orders the stipulating parties to comply with all terms of the Stipulation. The
2002 Settlement Agreement is generally affirmed as part of the Judgment and its terms
incorporated into the Stipulation. However provisions of the Stipulation supersede the 2002
settlement agreement in the areas of continuing jurisdiction and groundwater monitoring,
reporting.
As specified in the Judgment, the Northern Cities agencies conduct groundwater monitoring
in the Northern Cities Management Area. As shown in Figure 2, the Northern Cities
Management Area (NCMA) represents the northernmost portion of the Santa Maria
Groundwater Basin. Adjoining the NCMA to the southeast is the Nipomo Mesa
Management Area (NMMA), while the Santa Maria Valley Management Area encompasses
the remainder of the groundwater basin.
Agenda Item 11.a.
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2011 ANNUAL MONITORING REPORT
NORTHERN CITIES MANAGEMENT AREA
In accordance with requirements of the Judgment, the agencies comprising the NCMA group
collect and analyze data pertinent to water supply and demand, including:
Land and water uses in the basin
Sources of supply to meet those uses
Groundwater conditions (including water levels and water quality)
The Monitoring Program gathers and compiles pertinent information on a calendar year basis
through requests to public agencies, necessary field work, and from online sources. Periodic
reports such as Urban Water Management Plans (UWMP) prepared by the Cities of Arroyo
Grande, Grover Beach and Pismo Beach provide information on planning to meet future
demand. Annual data are added to the comprehensive Northern Cities Management Area
Database (NCMA DB) and analyzed. Results of the data compilation and analysis for
calendar year 201 1 are documented and discussed in this Annual Report.
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Climate Conditions
Figure 4 shows monthly rainfall and evapotranspiration for 201 1, and for comparison,
average monthly historical rainfall and evapotranspiration. Each year climatalogic (weather)
and hydrologic (stream flow) data for the NCMA are added to the NCMA DB. These data
are discussed below.
2.1 Precipitation
Historical rainfall data have been compiled on a monthly basis for the National Oceanic and
Atmospheric Administration (NOAA) Pismo Beach station for 1949 to 2005, while
precipitation data from 2005 to present are available from a County-operated rain gage in
Oceano. Figure 3 is a composite graph combining data from the two stations and illustrating
annual rainfall totals from 1950 through 201 1 (on a calendar year basis). Annual average
rainfall for the NCMA is approximately 16 inches.
Above average rainfall occurred during the months of March, May, and June of 20 1 1,
however the total rainfall for 201 1 was only 78.8 percent of the average annual rainfall. This
follows the period from 2007 through 2009, during which the precipitation conditions within
the NCMA were the second driest on record, and 2010, during which the precipitation totals
within NCMA were the seventh highest on record, going back to 1950. The average three
year precipitation for the period from 2007 through 2009 was only slightly higher than the
average precipitation for the driest three year period on record, which ended in 1990. In
201 0, the total precipitation was 163 percent of the average annual rainfall. Inspection of
Figure 3 plots annual rainfall and shows several multi-year drought cycles followed by cycles
of above average rainfa11 (such as occurred from March 1991 to March 1998).
Figure 4 shows monthly rainfall and evapotranspiration data on a calendar year basis for
201 1 and, for comparison, the average monthly rainfall. Most rainfall typically occurs from
November through April. The year 201 1 was marked by substantially lower than average
rainfall in January, February, April, and December, while rainfall in the months of March,
May and June were above average. The remaining months, most of which were in the dry
season, experienced slightly below average rainfall. Rainfall only exceeded
evapotranspiration in March, 201 1. Deep percolation, thus groundwater recharge, would
have occurred during March, given that rainfall penetrated below the vegetation's root zone.
Agenda Item 11.a.
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2.2 Evapotranspiration
The California Irrigation Management Information System (CIMIS) maintains weather
stations in locations throughout the state in order to provide real time wind speed, humidity
and evapotranspiration data. Nipomo and San Luis Obispo stations have gathered data since
2006 and 1986, respectively. Monthly ET data from the two stations is shown in Figure 4 for
201 1 and average conditions. Evapotranspiration rate affects recharge potential of rainfall
and the amount of outdoor water use (irrigation).
Agenda Item 11.a.
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3 Water Demand
2011 ANNUAL MONITORING REPORT
NORTHERN CITIES MANAGEMENT AREA
Water demand refers to the total amount of water used to satisfy various needs. In the
NCMA, water is primarily used to satisfy urban demand and applied irrigation demand. The
third category, rural demand includes small community water systems, domestic, recreational
and agriculture-related businesses and is relatively minor. Table 1 presents water demands
for urban uses, applied irrigation, and rural uses. The values shown in Table 1 represent
water demand in acre-feet per year (AFY). Comparing demand to available supply (Section
4) allows development and comparison of water source options under a given set of
conditions.
Table 1 Total Demand for Groundwater and Surface Water, AFY
3.1 Urban Demand
Actual urban water demands are presented in Table 1 for each of the Northern Cities from
2005 through 201 1. These demand values reflect reported Lopez Lake and State Water
Project (SWP) purchases and groundwater production data, which are incorporated in the
NCMA database. These water demand values represent all water used within the entire
service areas of the four agencies comprising Northern Cities, including the portions of
Arroyo Grande and Pismo Beach that extend outside the NCMA (Figure 2). Urban demand
amounts reported include water delivered to municipal customers and all other water used by
the respective municipal agency as well as system losses.
Rural
Water
36
36
36
36
36
38
38
Total
Demand
10,707
10,545
11,760
11,549
10,958
9,636
10,253
Total
Urban
8.61 5
8,453
8,982
8,771
8,180
7,542
7,473
Year
2005
2006
2007
2008
2009
201 0
201 1
Applied
Irrigation
2,056
2,056
2.742
2,742
2,742
2,056
2,742
Pismo
Beach
2,142
2,121
2,261
2,208
2,039
1,944
1,912
Oceano
CSD
93 1
882
944
933
885
855
852
Arroyo
Grande
3,460
3,425
3,690
3,579
3,315
2,956
2,922
Grover
Beach
2,082
2,025
2,087
2,051
1.941
1,787
1,787
Agenda Item 11.a.
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3.2 Applied Irrigation Demand
Applied Irrigation Demand is an in-direct measurement that requires a method for estimating
Annual Gross Irrigation Water Requirement (AGIR). The San Luis Obispo County Water
Master Plan uses a crop-specific method for calculating AGIR in acre-feet per year per acre
(AFYIacre), based on crop evapotranspiration, effective rainfall, leaching requirements,
irrigation efficiency, and frost protection. Calculation of the AGIR, which is then used to
estimate the applied water for irrigation for an aggregated area, is described in the following
equation:
AGIR (Ft) = [(Crop ET - Effective Rainfall) I ((l-Leaching Requirement) x Irrigation
Efficiency)] + Frost Protection Water
The calculated crop-specific applied water is multiplied by specific crop acres to obtain the
irrigation demand for a given crop type. The individual crop demands are then summed for
the agricultural area of interest. The San Luis Obispo County Water Master Plan is currently
being completed and will contain a determination of irrigated acres by a GIs method for
areas in the county, with the exception of the NCMA, NMMA, and the SMVMA areas, since
these areas had completed their own land use determinations.
In the NCMA, annual crop statistics are aggregated into crop categories and the specific farm
field location is not published or readily available; thus, the necessary land use data with
crop-specific surveys are not available at this time to be used to calculate the annual
irrigation demand based on the crop survey information. The representative land use survey
information provides an estimate of crop-specific acres that are aggregated into larger
categories, such as, truck crops. In order to estimate the anriual irrigation demand for the
NCMA, the crop acres represented by an aggregated category are multiplied by the estimated
gross irrigation requirements per acre from the San Luis Obispo County Water Master Plan.
The 201 1 annual report estimates the applied irrigation demand based on the method
established in the previous annual reports completed by Todd Engineers. The estimate of
gross irrigation requirements is based on the San Luis Obispo County Water Master Plan
Update which includes low, average, and high estimates of irrigation demand by crop type
for each of the Water Planning Areas WAS) in the County. The range in estimated
irrigation demands is based upon climactic conditions and average irrigation efficiency, and
includes double cropping for the category truck crops. Since the Water Master Plan Update
does not include gross irrigation requirements for turf grass, the values for pasture grass were
applied to turf grass areas in the NCMA to estimate their applied irrigation demand,
recognizing that pasture grass is the most similar to turf grass. The representative gross
irrigation requirements for crop groups are presented in Table 2.
As stated in the previous Annual Report, the areal extent of cultivated agricultural areas in
the NCMA has been quantified using a past land use survey by the San Luis Obispo County
Agricultural Commission. Communication with the San Luis Obispo Agricultural
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Commission Office conferred the observation that agriculture land use in the NCh4A for
201 1 has remained consistent for the past several years. Given this observation, the
estimated agriculture acreage remained based on agriculture land use survey data and the
methods used by Todd Engineers. The San Luis Obispo Agriculture Office indicated
agriculture land use data, updated by their GIs staff, may become available in future years.
For the 201 1 estimate, the same land use acres were used to calculate the applied irrigation
demand as identified in the previous annual report. The areas with irrigated turf' grass have
been previously identified by public works personnel within the Northern Cities. The
acreages of these areas have been measured from publically available aerial photographs
using GIs software tools.
Table 2 Gross Irrigation Requirement for WPA 5 by Crop Group
Crop Type
Low Annual
Demand
( AFYlacre)
Alfalfa
Nursew
Average Annual
Demand
(AFYlacre)
Pasture
Turf Grass
Citrus
The 201 1 agricultural water demand in NCh4A is based on previous year estimates for land
use and since the acres of land use have no indication they have changed. There are about
1,600 acres of irrigated agriculture within the NCh4A of which approximately four acres are
in nursery crops, and the remainder is truck crops such as broccoli, onions, and strawberries,
the total acres for irrigated crops in the NCh4A. There is a combined total of 44 acres of
irrigated turf' grass at the Oceano Elementary School, Arroyo Grande High School, Harloe
Elementary School, and the Le Sage Riviera Golf Course. For 201 1, the annual precipitation
and evapotranspiration have been compared to average conditions to determine if the year in
question had a low, average, or high irrigation water demand.
High Annual
Demand
( AFYlacre)
2.5
1.4
Deciduous
Truck (vegetable)
Vinevard
For this evaluation, average irrigation efficiencies are assumed for the NCh4A. Therefore, the
annual irrigation demand for each crop type is assumed to be dependant only on that year's
precipitation and evapotranspiration. The range of demand estimates for all applied
irrigation uses are as follows:
Wet years: 2,056 AFY (2005,2006, and 2010)
2.6
2.6
1.3
Average years: 2,397 AFY (2004)
Dry years: 2,742 AFY (2007,2008,2009, and 201 1)
2.9
1.7
2.6
1.2
0 9
3.3
2.1
3.0
3.0
1.6
3.5
3.5
1.9
2.9
1.4
1.1
3.2
1.6
1.4
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3.3 Rural Demand
In the NCMA rural water demand refers to uses not designated as urban demand or applied
irrigation demand and includes small community water systems, individual domestic system,
recreational uses and agriculture-related business systems. Small community water systems
using groundwater in the NCMA were identified initially through review of a list of water
purveyors compiled in the 2007 San Luis Obispo County Integrated Regional Water
Management Plan. These include the Halcyon Water System, Ken Mar Gardens, and Pacific
Dunes RV Resort. 'The Halcyon Water System serves 35 homes in the community of
Halcyon, while Ken Mar Gardens provides water supply to 48 mobile homes on South
Halcyon Road. The Pacific Dunes RV Resort, with 2 I5 RV sites, provides water supply to a
largely transitory population and nearby riding stable. In addition, about 25 homes and
businesses have been identified through inspection of aerial photographs of rural areas within
NCMA. Irrigation of schools and parks from privately operated wells is included in the
applied irrigation demand section. Two mobile home communities, Grande Mobile and
Halcyon Estates, are served by Oceano CSD through the distribution system of Arroyo
Grande. The demand summary of Oceano CSD includes these two communities. Based on
prior reports, it is assumed that the number of private wells is negligible within the service
areas of the four Northern Cities. 'The estimated rural water demand is shown in Table 3.
Table 3 Estimated Rural Water Demand
1 -Water demandlunit based on 2000 and 2005 Grover Beach water use per connection, 2005 UWMP.
2 - Demand based on metered water usage.
3 -Water demandlunit assumes 50 percent annual occupancy and 0.06 AFY per occupied site.
3.4 Changes in Water Demand
Notes
1
2
3
1
In general, urban water demand has varied, with a slight decrease during the past couple
years (Table 1). This change is attributed primarily to the relatively slower economy and the
conservation activities implemented by the Northern Cities in response to the prolonged
drought and potential threat of seawater intrusion. In the applied irrigation category,
agricultural acreage has remained fairly constant. Thus annual water demand for applied
irrigation varies mostly with weather conditions. Acknowledging the variability due to
weather conditions (see Table l), applied irrigation water demand is not expected to change
significantly, given the relative stability of applied irrigation acreage and cropping patterns in
the NCMA south of Arroyo Grande Creek. Changes in rural demand have not been
significant.
Groundwater User
Halcyon Water System
Ken Mar Gardens
Pacific Dunes RV Resort
Rural Users
8
GEI cat-
w-8 r-, at-
Current Estimated Rural Use
Estimated Water
Demand, AFY per Unit
0.40
0.18
0.03
0.40
No.
O! Unlts
35
48
215
25
38
Estimated Water
Demand, AFY
14
8.7
6
10
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4 Water Sur>r>lv Sources
Section 4 provides an overview of NCMA water supply sources, presents groundwater
conditions that occurred in 201 1, and discusses threats to water supply.
4.1 Sources of Supply
There are three major sources of water that supply the NCMA. These are the Lopez Lake,
the State Water Project Coastal Branch, and groundwater pumping. Each source of supply
has a defined delivery volume which varies from year to year based on a number of factors.
Both supply and demand are discussed below; demand is discussed in further detail in
Section 5.
4.1.1 Lopez Lake Supply
Lopez Lake and Water Treatment Plant is operated by FC&WCD Zone 3 and serves water to
all four agencies in the NCMA as well as making releases for habitat conservation and
agricultural purposes. The safe yield of Lopez Lake is 8,730 AFY, which reflects the amount
of sustainable water supply during a drought of defined severity. Of this yield, 4,530 AFY
have been apportioned by agreements to contractors, including each of the Northern Cities
plus County Service Area (CSA) 12 (in the Avila Beach area). Zone 3 entitlements are
summarized in Table 4. Of the safe yield, 4,200 AFY is available for release downstream to
maintain flows in Arroyo Grande Creek and provide groundwater recharge.
Table 4 Zone 3 Contractor Water Entitlement (AFY)
Contractor I Water ;;:ti;ment,
City of Arroyo Grande I 2,290
City of Grover Beach I 800
City of Pisrno Beach
Oceano CSD
Downstream Releases 4,200
896
303
CSA 12 (not in NCMA)
Total
Safe Yield of Lopez Lake 8,730
24 1
4,530
Source: SLO County FCBWCD. Zone 3 UWMP 2005 Update
During 201 1 the total discharge from Lopez Lake was 74 18.4 AF, of which 4,606.8 AF was
delivered to contractors and 2,811.6 AF was released downstream to maintain flow in Arroyo
Grande Creek (actual deliveries are shown in Table 7). In the past, when management of
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releases resulted in a portion of the 4,200 AFY remaining in the reservoir, the water was
offered to the contractors as surplus water. Surplus water was available in 201 1; the NCMA
agencies took 2,226.5 AF of delivery.
4.1.2 State Water Project
Pismo Beach and Oceano CSD have contracts with the FC&WCD to receive water from the
SWP. The FC&WCD serves as the SWP contractor, providing the imported water to local
retailers through the Coastal Branch pipeline. Pismo Beach has a contractual allocation of
1,240 AFY while Oceano CSD has a contractual allocation of 750 AFY. The FC&WCD
holds SWP allocation in excess of the amount contracted for delivery to local agencies. This
allocation (sometimes referred to as a "drought buffer") is available to augment requests
when the state wide SWP allocations are insufficient to meet local needs.
In response to drought in SWP source areas, the initial allocation to SWP contractors for
201 1 was 25 percent of contractual allocation amounts, which was subsequently increased to
70 percent in March, and ultimately 80 percent in May due to above average precipitation in
late 2010 and spring 201 1. However, due to the nature of its contractual arrangements,
FC&WCD needed to request only a fraction of its entire 25,000 AF allocation in 201 1 to
satisfy local contractors. The requested amount met all of the local purveyors' requests.
Unlike many water agencies in California that have experienced substantial restrictions in
SWP deliveries, Pismo Beach and Oceano CSD (the only SWP participants in the NCMA)
were both able to receive 100 percent of their requested 201 1 SWP allocation. Pismo Beach
actually took delivery of 809.4 AF, while Oceano CSD took delivery of 750.0 AF, for a total
of 1,559.4 AF of SWP water (Shown in Table 7, rounded to the nearest AF).
4.1.3 Groundwater
Each of the NCMA agencies have established groundwater supplies using wells which draw
from developed aquifers in the northern portion of the NCMA. Groundwater also supplies
applied irrigation and rural uses in the NCMA. Groundwater use in the NCMA is governed
by the Judgment and the 2002 Settlement Agreement which establishes that groundwater will
continue to be allotted and independently managed by the 'Worthern Parties" (Northern
Cities, NCMA overlying owners, and the FC&WCD). The Settlement Agreement initially
allots 57 percent of groundwater safe yield to agriculture and 43 percent to the cities and
stipulates that any increase or decrease in groundwater yield will be shared by the cities and
landowners on a pro rata basis. However the Judgment after Trial, filed January 25,2008
states:
4. (a) The Northern Cities have a prior and paramount right to produce 7,300
acre-feet of water per yearjom the Northern Cities Area of the Basin; and (b) the
Non-Stipulating parties have no overlying, appropriative, or other right to
produce any water supplies in the Northern Cities Area of the Basin.
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A safe yield value of 9,500 AFY for the NCMA groundwater basin was cited in the 2002
Groundwater Management Agreement among the Northern Cities with allotments for applied
irrigation (5,300 AFY), subsurface outflow to the ocean (200 AFY), and urban use (4,000
AFY). The Management Agreement's safe yield allotment for urban use was subdivided as
follows:
City of Arroyo Grande 1,202 AFY
City of Grover Beach 1,198 AFY
City of Pismo Beach 700 AFY
Oceano Community Services District 900 AFY
According to the "Water Balance Report" prepared for NCMA in 2007 (Todd Engineers,
2007), the Groundwater Management Agreement's subdivision for applied irrigation is
higher than the actual applied irrigation groundwater use and the amount designated for
subsurface outflow is unreasonably low. Since the amount of agriculture expansion is not
significant and the long term increased use is unlikely, the current balance of water use
between agriculture and municipal uses has been sustainable for the last 40 years.
Maintenance of subsurface outflow along the coast is essential to preventing seawater
intrusion. While the minimum subsurface outflow needed to prevent seawater intrusion is
unknown, a regional outflow on the order of 3,000 AFY has been estimated as a reasonable
approximation (Todd Engineers, 2007).
The 2002 Settlement Agreement provides that the various urban parties' allotments can be
increased when land within the corporate boundaries is converted from agricultural uses to
urban uses, referred to as an agricultural conversion credit Agricultural credits for the Cities
of Arroyo Grande and Grover Beach changed slightly from 2010. The agricultural credit for
201 1 for Arroyo Grande and Grover Beach and are 121 AFY and 209 AFY, respectively, for
a total of 330 AFY.
4.1.4 Developed Water
As defined in the Stipulation, "developed water" is "Groundwater derived from human
intervention" and includes "Lopez Lake Water, Return Flow, and recharge resulting from
storm water percolation ponds." Return flows result from deep percolation of water used in
irrigation that is in excess of plant needs. Return flows result from outdoor uses of Lopez
Lake and SWP deliveries. These return flows have not been recently estimated, but would be
considered part of the groundwater basin yield.
In 2008, the Cities of Arroyo Grande, Grover Beach, and Pismo Beach prepared storm water
management plans; the cities currently are working with the Central Coast Regional Water
Quality Control Board to address local storm water quality issues. In order to control storm
water runoff, each City anticipates development of retention or detention ponds associated
with new development that may provide groundwater recharge. No new ponds were installed
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in the NCMA and no new data were available for 201 1 so previous estimates of recharge
were used in this report. Estimated recharge values should be updated and refined as new
recharge facilities are installed and as additional information on flow rates, pond size,
infiltration rates, and tributary watershed area becomes available.
Construction of recharge basins or other means to increase groundwater recharge could
substantially augment the yield of the groundwater basin and thus warrant provision of
recharge credits to one of more of the Northern Cities. Pursuant to the Settlement agreement,
recharge credits would be based on a mutually-accepted methodology to evaluate the amount
of recharge. This would involve quantification of such factors as Lopez Lake and State
Water Recharge, storm water runoff amounts, determination of effective recharge under
various conditions, and methods to document actual recharge to developed aquifers.
4.1.5 Water Use by Supply Source
Table 5 summarizes the water supplies currently available to the Northern Cities in terms of
Lopez Lake entitlements, SWP allocations, groundwater allotments, and agricultural credits.
In addition to directly available supplies, 201 1 was the 3rd year of a 5 year agreement
between Arroyo Grande and Oceano CSD for the temporary purchase of groundwater or
Lopez Lake supplies. The category of "Other Supplies" includes groundwater pumped
outside the NCMA boundaries.
Table 5 Available Urban Water Supplies, AFY
Figure 5 illustrates the water use by supply source for each NCMA city since 1999. The
graphs reveal changes in water supply availability and use over time, including the increased
use of SWP water (to a maximum in 2001) and reduced and less variable Lopez Lake water
use due to the unavailability of Lopez Lake surplus flows from 2002 to 2008. No recycled
water was available in 201 1. Plans have been developed to provide recycled water facilities.
See Section 6.2.5.
Figure 6 shows total NCMA water use for each supply source: Lopez Lake, SWP, and
groundwater. As shown, the full amount of Lopez Lake supply (4,289 MY) is currently
used. In 2001 through 2003, SWP supplies (1,850 MY) were used to the maximum extent.
From 2004 to 2008, S WP use decreased to just over 1,100 MY, mostly reflecting a partial
Temporarily
Purchased
100
0
0
-1 00
0
Urban
Area
Arroyo
Grande
Grover
Beach
Pismo
Beach
Oceano
CSD
Total
Groundwater
Allotment
1,202
1,198
700
900
4,000
Other
Supplies
160
0
0
0
160
Ag
Credit
121
209
0
0
330
Lopez Lake
Entitlement
2,290
800
896
303
4,289
Total
3,873
2,207
2,836
1,853
10,769
SWP
Allocation
0
0
1,240
750
1,990
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shift by Pismo Beach from SWP to groundwater supply. This changed in 2009 and 20 I0
when Pismo Beach increased SWP use and significantly decreased groundwater use to
provide a more economical water supply and to ease the burden on the groundwater basin
during the drought (see Figure 5). In 201 1 Pismo Beach took delivery of 809.40 AF of SWP
water and pumped 47.1 1 AF from the groundwater basin. In 20 1 1 Oceano CSD took
delivery of 750.00 AF of SWP water and pumped 44.28 AF from the groundwater basin.
Total NCMA groundwater use is shown in Figure 6. Estimated applied irrigation and rural
uses are added to the urban uses detailed in Figure 5. From 1999 through 20 1 1, total
estimated groundwater use averaged approximately 5,165 AFY and exceeded 6,000 AFY in
2007 and 2008. With an estimated safe yield of 9,500 AFY, the remaining groundwater
represents storage and outflow to the ocean, an unknown but major portion of which is
needed to repel seawater intrusion. The overall groundwater use in 2009 was slightly above
average, though in 2010 and 201 1 overall groundwater use was significantly reduced and
remained below average.
4.2 Groundwater Conditions
The NCMA groundwater monitoring program comprises: I) compilation of groundwater
elevation data from San Luis Obispo County, 2) water quality and groundwater elevation
monitoring data from the network of sentry wells in the NCMA, 3) water quality data from
the California Department of Public Health @pH), and 4) groundwater elevation data from
municipal pumping wells. Analysis of these data is summarized below in accordance with
the July 2008 Northern Cities Monitoring Program.
4.2.1 Groundwater Monitoring Network
Approximately 145 wells within the NCMA were monitored by the County at some time
during the past few decades. The County currently monitors 38 wells on a semi-annual basis
(April and October), including five "sentry well" clusters (piezometers) located along the
coast. The County monitors more than 70 additional wells in southern San Luis Obispo
County. Following the findings of the 2008 Amual Report, the Northern Cities initiated a
quarterly sentry well monitoring program to supplement the County's semi-annual schedule.
To monitor overall changes in groundwater conditions, representative wells within the
NCMA were selected for preparation of hydrographs and evaluation of water level changes.
Wells were selected based on the following criteria:
Part of the County's current monitoring program
Detailed location information available
Geographically well distributed
Long and relatively complete record
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It should be noted that many of the wells that have been measured are production wells that
were not designed for monitoring purposes and may be screened in various producing zones.
Moreover, many of the wells are active production wells or located near active wells and thus
are subject localized pumping effects that result in measurements that are lower than the
"static" or more broadly representative water level. These effects are not always apparent at
the time of measurement. As a result, the data cannot easily be identified as representing
static groundwater levels in specific zones (e.g., unconfined or deep confined). Hence, the
data should be considered as a whole in developing a general representation of groundwater
conditions.
The "sentry wells", shown on Figure 7, are a critical element of the groundwater monitoring
network; they provide an early warning system to identify and quantify potential seawater
intrusion episodes in the basin. Each sentry well comprises a cluster of multiple wells
allowing for the measurement of groundwater elevation and quality from discrete depths.
Also shown on Figure 7 is the Oceano CSD Observation well, a dedicated monitor well
cluster located just seaward of Oceano CSD production wells 7 and 8. Figure 8 shows the
depth and well names of the sentry well clusters and the Oceano CSD observation well
cluster. The wells are divided into three basic depth categories: shallow, intermediate, and
deep. Since the initiation of the sentry well monitoring program 12 quarterly events have
been completed; with one each in May, August, and October 2009 and winter, spring,
summer and fall 20 10 and 20 1 1 and one in January 201 2. These monitoring events include
collection of synoptic groundwater elevation data and water quality samples for laboratory
analysis.
4.2.2 Groundwater Levels
Groundwater elevation data is gathered from the network of wells listed in Table 6a and 6b.
Water level measurements in these wells were used to monitor effects of groundwater use,
groundwater recharge, and as an indicator of risk of seawater intrusion. Analysis of these
groundwater elevation data has included development of groundwater surface contour maps,
hydrographs, and an index of key sentry well levels over time (Figures 9 through 12).
Contoured groundwater elevations for the April (Spring 20 11) and November (Fall 201 1)
monitoring events, including data from the County of San Luis Obispo, are shown on Figures
9A and 9B. Figure 9A shows groundwater elevations for Spring 20 1 1 highest in the eastern
portion of the NCMA and approximately 10 feet above sea level along the shore line. No
comparison with prior years is possible since this is the first year Spring contours were
prepared.
Groundwater elevations in November 201 1 (Figure 9B) were highest in the eastern portion of
the NCMA near Arroyo Grande and Highway 101. Groundwater elevations were above mean
sea level (msl) throughout the NCMA during the November monitoring event. Significantly,
water level elevations were approximately 5 feet above sea level along the shoreline. 'This
represents a significant recovery of groundwater elevations as compared to October 2008 and
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above levels measured in October 2009. The water levels are similar to those measured in
20 10. This recovery is important because in October 2008 water level elevations were as
much as 10 feet below sea level in the north-central portion of the NCMA (Todd Engineers,
2009). Because the area below mean sea level appeared to extend to the coast there was
potential for seawater intrusion (Todd Engineers, 2008). However, there remains an apparent
depression in the water table in the so-called "pumping trough" which is located well south
of the municipal well fields.
Figure 10 shows the locations of selected wells. Hydrographs shown on Figure 10 illustrate
long-term changes in groundwater levels in the NCMA. To provide geographic context,
hydrographs from wells located just east of the NCMA in the Nipomo Mesa Management
Area as presented as well. Noting that these hydrographs represent localized conditions at
each well, most of the hydrographs indicate that groundwater elevations have historically
varied over a range of about 20 feet above mean sea level and in the case of two inland wells,
40 feet.
The upper left and middle left portions of Figure 10 shows paired hydrographs for four wells
located near a persistent pumping trough. (It should be noted that these wells are near
municipal well fields and, depending on duration of pumping, water levels may remain
below levels in other areas of the basin for prolonged periods of time.) Although the data sets
are incomplete, the hydrographs show that, throughout the record, groundwater elevations in
these wells have generally been above mean sea level. However, an area of lower
groundwater elevations ("trough") beneath the active well field became more pronounced
during the period of reduced rainfall in 2007 and 2008. These wells remained above sea
level in 20 1 1.
Most of the hydrographs in Figure 10 show that groundwater elevations have recovered and
remained at levels similar to 2006 (a wet year); this cycle shows the result of drought and
increased pumping followed by recovery caused by increased rainfall and decreased pumping
(see Figure 6). Although somewhat above sea level, a depression in groundwater levels
persists in the area of the trough suggesting that the recharge and withdrawals are near
balance in the area. Changes in groundwater elevations within the NCMA that occurred
from October 2008 to October 201 1 have been evaluated in the preparation of this report.
Overall, water elevations within the NCMA remained constant during water year 201 1
compared to similar periods in 2010 with relatively insignificant increases or decreases in
elevation is some areas.
The sentry well clusters are the essential tool for tracking critical groundwater elevation
changes at the coast. As shown by the hydrographs for the five sentry well clusters in Figure
1 I, the sentry wells provide a long history of groundwater elevations. In addition,
groundwater elevations in these wells are monitored quarterly as part of the sentry well
monitoring program. The deepest wells in the clusters adjacent to the NCMA urban area
(wells 24803,30F03, and 30N02) are also screened at depths closely matching the screened
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depths of most local pumping wells. Hence, measured water elevations in these deepest wells
reflect the net effect of changing groundwater recharge and discharge conditions in the most-
used aquifer zone.
Averaging the groundwater elevations from these three wells provides a single,
representative index for tracking the status of the basin. Historical variation of this index is
shown as the average deep sentry well elevations on Figure 12A. Figure 12A clearly shows
three years of drought followed by recovery in this highly-developed aquifer zone.
Specifically, the graph shows that this index has improved significantly since the 2008
Annual Report.
In order to measure potential short term water level fluctuations due to pumping, tidal
fluctuation or other factors the NCMA group approved installation of pressure and electrical
conductivity transducers in deepest wells at three of the sentry well locations (32Sl12E-
24803; 32Sl13E-30F03; and 32Sl13E-30N02). In addition, a transducer was placed in well
32Sl12E-24BO1 to measure changes in water levels and salinity in the shallow groundwater
that may be influenced by storms and other coastal processes. Since April 20,201 1 the
measurement interval has been 30 minutes (Figures 12B through 12E).
Data from the continuous monitoring sensors shows water level changes of 0.2 to 1.6 ft in 6
hours with larger changes occurring in multi-day time frames. Water level changes exhibit
timing that is similar to ocean tides measured in nearby Port San Luis. In the cases of
32S/12E-24B01,32S/12E-24B03, and 32Sl13E-30N02, fluctuations also reflect longer term
variation in the tidal range.
Direct influence of the rainfall event of mid-March is apparent in the deeper sentry wells -
32Sl12E-24B03, 32Sl13E-30N02 and 32Sl13E-30F03. Well 32Sl13E-30F03 shows two
periods of water level increases beginning in mid-August and early September. Wells
32Sl12E-24B03 and 32Sl13E-30N02 shows increases at the same time but with significantly
less magnitude. Data from continuous monitors also shows three distinct periods of decline
and recovery in wells 32S/12E-24B03,32S/13E-30N02 and 32Sl13E-30F03. Daily pumping
records from the municipal water suppliers show a correlation between increased
groundwater extraction and these changes. Detailed evaluation of the data may provide
insight regarding general aquifer characteristics and response to variation in pumping rate at
locations along the shoreline. Additional well data may allow more detailed analysis of this
response in the future.
4.2.3 Water Quality
Water is used in several ways in the NCMA; each use requires a certain minimum water
quality. Since contaminants from seawater intrusion or anthropogenic sources can
potentially lower the quality of water in the basin, water quality is monitored at several
locations in the NCMA. In the NCMA area, water quality data are available from dedicated
monitoring wells, from water supply wells and from surface water. Four well clusters
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located along the coast were originally installed by the California Department of Water
Resources to monitor for seawater intrusion. Each of these "sentry wells" has two or three
individual wells (piezometers) completed at different depths. In addition, the Oceano CSD
observation well cluster (located near Highway 1 in Oceano) includes four individual
piezometers. Water quality information from each of the sentry wells and the Oceano CSD
monitoring wells is gathered quarterly. In addition to the monitoring wells, consolidated
water quality information from the DPH for local municipal wells was reviewed.
4.2.3.1 Sentry Wells
Four separate monitoring events occurred in 201 1, with each piezometer in the sentry wells
and in the Oceano CSD well measured in January, April, July, and November 201 1. During
each event, the wells were all sampled in accordance with ASTM International Standard
D4448-01. Water quality data from these events and available historical data from these
wells are presented on Tables 6A and 6B. Beginning in October 201 1, water quality samples
were obtained directly from the pump used to evacuate each well. Since water quality trends
are used to monitor for seawater intrusion, data collected in 201 1 were added to previous data
and the variation of selected constituents have been plotted against time. (Other
geochemical plots are discussed below.) Figure 13 and Figure 14 are meant to show
variation of chloride and TDS concentration, respectively, in 201 1. Data contained in Table
6A shows a wide variation in water quality during the years 2009 through 20 1 1. However,
samples obtained in 201 1 show less variation and general improvement in overall quality
compared to 2009. Todd Engineers (201 0) suggested the observed variation in water quality
data could be due to a number of factors including: variable permeability of geologic
materials, potential mixing with seawater, ion exchange in clay-rich units, and variability in
surface recharge sources, such as Arroyo Grande and Meadow Creeks. Changes in
groundwater demand and abundant rainfall may have contributed to the general improvement
of groundwater quality in 201 1. These factors are discussed in more detail in Section 5.
Most wells showed similar chemical quality to results from 2010. With the exception of
shallow well 32SI12E-24B01, no wells showed evidence of higher TDS or Chloride which
may be indicators of seawater intrusion. Several wells showed continued improvement of
water quality compared to 2008,2009 and 2010 monitoring results. Key observations are
discussed below.
Agenda Item 11.a.
Page 23
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Table 6b: Northern Cities Sentry Well Water Quality Data Summary
Production Interval
Des. by: CNT
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Agenda Item 11.a.
Page 29
2 of
Table 6b: Northern Cities Sentry Well Water Quality Data Summary
Production Interval
Des. by: CNT
Ckd. by: MKR 08.09.10
Agenda Item 11.a.
Page 30
3 of
Table 6b: Northern Cities Sentry Well Water Quality Data Summary
Production Interval
Des. by: CNT
Ckd. by: MKR 08.09.10
Agenda Item 11.a.
Page 31
4 of
Table 6b: Northern Cities Sentry Well Water Quality Data Summary
Des. by: CNT
Ckd. by: MKR 08.09.10
Agenda Item 11.a.
Page 32
5 of
Table 6b: Northern Cities Sentry Well Water Quality Data Summary
Production Interval
Des. by: CNT
Ckd. by: MKR 08.09.10
Agenda Item 11.a.
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Sentry well cluster 32Sl13E 30N is located west of Highway 1 in Oceano and includes three
piezometers. The sentry well cluster is also in an area of sufficient groundwater production to
cause a broad lowering of the water table (called a pumping trough by Todd Engineers 2010).
The deep and intermediate level piezometers at this location showed low groundwater levels
in 2008 and 2009. Data from this sentry well cluster was interpreted to indicate localized
seawater intrusion affecting the deep zone (30N02) and, to a lesser extent, the middle zone
(30N03) in 2009.
Data collected in 2010 from piezometers 30N02 and 30N03 show geochemical signatures of
seawater intrusion on Schoeller geochemical plots (Figure 15). (A Schoeller diagram is a
graphical representation of common cation and anion concentrations in water expressed in
milliequivalents per liter (meqll). Because several samples may be plotted on the same
graph, variation in hydrogeochemical water characteristics may be easily recognized.) The
most recent water quality data from this well cluster (January, April, July and October 201 1)
show significant improvement in water quality in 30N02, including a reduction in the
concentrations of seawater indicators and a signature similar to the historical signature of
groundwater in 30N02.
These water quality changes indicate that the local interfacelmixing zone between seawater
and fresh groundwater has shifted in the seaward direction. The location of the seawater
interface is not known due to the heterogeneity of the aquifer; the only indication is when one
or more monitored wells show an increase in TDS and a geochemical signature resembling
seawater. Based on experience in the NCMA, retreat of the interface may be reversed, and
again become shoreward, if seaward gradients are reduced or reversed. These changes may
be brought on by reduced recharge (e.g. drought conditions) or if pumping exceeds available
groundwater supply, or both. Ongoing sentry well monitoring is necessary to provide an
early warning of future migration of the interface.
The shallow well in sentry well cluster 32Sl12E 24B has historically contained brackish
water. This sentry well is located in the northwestern comer of the basin in Pismo Beach. The
shallow well (24BO1) shows a similar geochemical signature to that of seawater. Water
samples from this well historically have shown high sodium and chloride concentrations.
While these data have been interpreted by the California Department of Water Resources to
be the result of solution of residual marine and evaporative salts indigenous to the geologic
environment in this part of the basin, there may be another source. The location of 32Sl12E
24B is near the lagoon at the mouth of Pismo Creek. This area is subject to storm surge and
local flooding during storm and high sea conditions. The water sample from the shallow
piezometer (24B01) showed elevated CI and Na in October 2010 and all quarterly samples
taken in 201 1 while samples from the two deeper piezometers showed no such effect.
Occasional downward percolation of seawater or brackish lagoon water may influence the
quality of sample from the shallow piezometer (24BO I). A sensor has been installed to
measure short term fluctuations in water level and TDS to provide additional insight as to the
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source of Cl and Na fluctuations. However, no correlation has been established between
exceptionally high tides or storm surges and increases in electrical conductivity.
Schoeller diagrams are geochemical representations that show the relative portions of major
water quality constituents based on ionic charge (in milliequivalents per liter or meq/L). This
approach allows graphical, or visual, means to evaluate measured water quality against
potential water sources. Figure 15 is a Schoeller diagram illustrating the water quality in the
DWR sentry wells for all of the 201 1 quarterly monitoring events. Each line of connected
points illustrates the water quality signature from a specific well (e.g., 30N02) for a given
sample period. For comparison, Figure 15 (the Schoeller diagram) also shows the typical
geochemical signature for seawater (in black) and the typical signature for a groundwater
basin water supply well (Grover Beach Well#l, labeled as "GW Base", in blue). Most of the
water quality samples plotted on the lower portion of the diagram are similar in shape to the
groundwater basin sample and are combined within the shaded area.
The Oceano CSD Observation well cluster has four wells; from shallow to deep, they are
identified as green, blue, silver, and yellow (see Figures 7 and 8). As documented in Table
6A, the Oceano CSD observation wells have been sampled in each quarterly monitoring
event since August 2009, but have not shown consistent water quality chemistry. In general,
the two deeper Oceano CSD Observation wells show similar water quality to the rest of the
groundwater basin with the exception of low sulfate values reported in August 2008.
Chloride concentrations have been slightly elevated and peaked in August 2009; however,
the overall water quality character does not appear to indicate seawater intrusion.
In the past few years the two shallow Oceano CSD Observation wells have shown significant
variation in several water quality parameters. In addition the wells recovered slowly after
purging done as part of sampling. This suggested some disconnect from the screened zone
and may indicate scaling or other chemical process is occurring. In order to restore function
of the Oceano CSD wells, high pressure flushing "jetting" of the screened interval in each
well was attempted.
Jetting to clear obstructions in the Oceano CSD "Green" and" Blue" wells were successful
and water levels were found to recover quickly after purging during sampling.
Rehabilitation of Oceano CSD Silver well found the casing blocked above the screened
interval suggestinga portion of the casing had failed. The screened interval in the Yellow
well was not jetted since the available equipment was not able to reach to the screened depth
of 625 fi. Because the Silver well appears to be damaged, water level measurements and
water quality samples were obtained from Oceano CSD production well #8 which has a
similar screened interval.
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As documented in Table 6A, chloride concentrations from the blue well were elevated in
October 2009 but have fallen since January 2010 and are now in a range similar to other
sentry wells. However, the water quality from this well suggests a signature close to
groundwater not seawater.
Public water supply systems are required to provide water quality information to the DPH.
Data submitted from the NCMA area was reviewed and most recent data added to the
NCMA data base. Although the data supplied by DPH does not include specific well
locations, individual public supply wells are identified and their location determined.
Although there is variation among wells, data from 201 1 suggest that water quality in
individual wells has remained generally consistent from year to year. High levels of Nitrate,
Selenium and Manganese are present is some wells. These wells are subject to more frequent
sampling and water produced is subject to treatment or blending. Treatment to remove
selenium and manganese and blending result in the water delivered through the municipal
systems meeting State and Federal water quality standards.
4.3 Threats to Water Supply
Both state-wide and local impacts to the NCMA water supply exist. Because the water
supply contains sources imported from other areas of the state, threats include State-wide
drought, effects of climate change in the SWP source area, management and environmental
protection issues in the Sacramento-San Joaquin Delta that affect the amount and reliability
of SWP deliveries and seismic risk to the SWP delivery system. Local potential impacts to
NCMA water supply similarly include extended drought and climate change that may affect
the yield from Lopez Lake as well as reduced recharge to the NCMA. There is a potential
impact from seawater intrusion if the groundwater system is not adequately monitored (as
discussed in the above section).
4.3.1 Threats to State Water Project Supply
Both extended drought and long term reduction in snowpack due to climate change can affect
deliveries from the State Water Project. California experienced a relatively short (2 year)
drought that resulted in below-average precipitation and runoff in the SWP source area;
runoff in 2007 and 2008 amounted to only 53 and 60 percent of average, respectively, and
runoff in 2009 was only slightly better at 85 percent. As a result, storage in SWP reservoirs
was reduced. In addition to drought conditions, SWP pumping capacity was reduced as the
result of a May 2007 federal court ruling to protect Delta smelt.
However, the threat of reduced delivery to local SWP users-Oceano CSD and Pismo
Beach-has not materialized to date, as San Luis Obispo County's allocation continues to be
approved in full because the FC&WCD is able to use some of its unallocated Table A
amount to augment deliveries. The FC&WCD hold SWP allocation in addition to the
amount needed to meet contracts with local agencies. In addition, the City of Pismo Beach
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acquired additional allocation form FC&WCD in 2012. Both sources of extra allocation may
be used as a drought buffer to provide additional deliveries during years when full deliveries
are not available. Nonetheless, in the future, the Delta's fragile ecosystem, uncertain
precipitation patterns and reduced snowrnelt may further reduce California's water supply
reliability with potential ramifications for Oceano CSD and Pismo Beach.
4.3.2 Sea water Intrusion
The NCMA is underlain by an accumulation of alluvial materials that slope gently offshore
and extend for many miles under the ocean (DWR 1985). Coarser materials within the
alluvial materials comprise aquifer zones that receive freshwater recharge in areas above sea
level. The elevation difference causes fresh water in the aquifers to flow toward the ocean
and form an interface between freshwater and seawater. Under natural and historical
conditions the differential pressure between the aquifer and seawater induces net outflow of
freshwater and establishes a dynamic interface between fresh water and salt water at depth.
Sufficient outflow prevents the dynamic interface from moving onshore. Sufficient
differential pressure to maintain a net outflow is indicated by onshore groundwater elevations
that are above mean sea level.
The Annual Report for CY 2008 documented that a portion of the NCMA groundwater basin
exhibited water surface elevations below sea level (Todd Engineers 2009). Hydrographs for
NCMA sentry wells (Figures I0 and 11) show coastal groundwater elevations that were at
relatively low levels for as long as two years. Such sustained low levels had not occurred
previously in the historical record and reflected the impact of drought on groundwater levels.
The low coastal groundwater levels indicated a potential for seawater intrusion. Increased
TDS, Na and CI concentrations were found in sentry well 32S/13E NO3 in August 2009 and
in 32S/13E NO2 in August and October 2009.
As documented in Section 4.2.2 of this report, groundwater elevations in October 201 1
showed a significant recovery of groundwater elevations relative to October 2008 and
October 2009. In addition, groundwater quality in the sentry wells NO2 and NO3 showed
improvement beginning in January 2010, including a reduction in the concentrations of
seawater indicators. Water elevation and quality measurements in 2009 through October
201 1 indicate the following:
The monitoring of the sentry wells, notably 32S/13E 30N, provides an early warning
of seawater intrusion. This well cluster may be relatively sensitive to seawater
intrusion because of its location near Arroyo Grande Creek and the more permeable
sediments deposited by the ancestral creek (Todd Engineers 201 0).
= The initial portions of the seawater/groundwater interface were detected onshore at
one site beginning with elevated Chloride levels in May 2009; by October 2009 the
interface had manifested in the middle and deep aquifer zones monitored by sentry
wells 30-NO2 and 30-N03. The extent to which seawater may have intruded other
localized aquifer zones along the coast without being detected in the NCMA sentry
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wells is unknown due to heterogeneity of the aquifer and spacing of sentry wells. This
uncertainty may be reduced by the ongoing collection of coastal groundwater
elevations in all sentry wells which are above mean sea level.
Above average precipitation and decreased groundwater withdrawal in 201 0 resulted
in increased water levels in the sentry wells on a comparative seasonal basis and an
apparent decrease in water table depression immediately south of lower Arroyo
Grande Creek. Average rainfall and groundwater withdrawals in 201 1 have
maintained this condition. (Figures 9A and 9B).
Water quality in most wells remains similar to historic measurements thus indicating
no effects of seawater intrusion.
4.3.3 Measures to Avoid Seawater Intrusion
In response to the early warning of seawater intrusion, the Northern Cities have developed
and implemented a water quality monitoring program for the sentry wells and Oceano CSD
Observation wells, as described above in Section 4.2.3. The Northern Cities, County
FC&WCD, and State of California have also worked cooperatively toward the protection of
the sentry wells as long-term monitoring sites. To address the impacts of potential seawater
intrusion, the Northern Cities have voluntarily reduced coastal groundwater pumping,
decreased overall water use via conservation, and initiated plans, studies and institutional
arrangements to secure additional surface water supplies. As a result, each of the 4 major
municipal water users reduced groundwater use between 25 and 90 percent between 2007
and 20 10. In 20 1 1, groundwater use ranged between 7 and 67 percent compared to 2007.
Pismo Beach and Oceano CSD reduced their groundwater demand between 90 and 50
percent respectively, in part by importing SWP supplies. A summary of the Northern Cities
Management Area objectives and activities is presented below in Section 6.
4.3.4 Change in Groundwater Recharge
Groundwater recharge includes subsurface flow from adjacent areas into aquifers serving as
water sources in the NCMA. An important source of subsurface recharge is flow from the
NMMA along the southeast boundary of the NCMA, estimated to be 1,300 AFY (DWR
2002). Contour maps prepared by DWR for spring 1975, 1985, 1995 and 2000 indicate a
growing depression in the NMMA associated with increased pumping during the same time
period @WR 2002).
More recently the NMMA Annual Report for 2009, (Figures 6-5 and 6-6) confirm
persistence of a WISE trending depression in the water level contours. Despite above
average rainfall in 2010, this zone of lower water levels appears to have persisted through fall
20 10 based on Figure 6-6 of the NMMA 201 0 Annual Report and into fall 20 1 I, as shown in
Figure 9B of this report.
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The NMMA 2010 Annual Report projects increasing water demand, thus extraction from
groundwater, in the NMMA. Although the NMMA may receive supplemental sources in the
future, ongoing or increasing amounts of groundwater extraction may continue to lower
ground water levels along the NMMA and NCMA boundary. Lower groundwater levels in
the boundary area will reduce flow to the NCMA or even reverse the flow; either
circumstance would further reduce groundwater available to users in the NCMA.
Some NCMA representatives have expressed their concerns to NMMA representatives
regarding the threats to the groundwater supply of both management areas, threats caused by
the increasing overdraft in the NMMA. The NCMA continues to work together with the
NMMA to better understand and solve these problems.
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This section presents a comparison of the 201 1 water supplies and demands of the Northern
Cities Management Area, applied irrigation, and rural water systems.
Table 5 in Section 4 outlines the Available Urban Water Supplies for each of the Northern
Cities. The total available urban water supply is 10,769 AFY. As discussed in Section 4, the
2002 Settlement Agreement estimated that the historical safe yield from the groundwater
basin was 9,500 AFY. Since all of the irrigation applied water demand is supplied by
groundwater, the total available applied irrigation supply is based on a portion of the
estimated groundwater safe yield, which was allocated as 5,300 AFY for agricultural and
rural use. The agricultural conversion of 330 AFY reduces this allocation to 4,970 AFY. Of
this estimated safe yield of 9,500 AFY, other than what is allocated for applied irrigation and
rural use, the remaining 4,000 AFY is allocated for urban water use and 200 AFY allocated
to subsurface outflow to the ocean.
In 201 1, the total urban water demand, based on production, was 7,473 AF. Based on 201 1
precipitation and ET data, 201 1 applied irrigation water use was estimated at 2,742 AF, while
rural water use was estimated at 38 AF. The total combined demand for the NCMA in 201 1
was 10,253 AF. The following Table 7 displays the water demand, by source, of each city
and agency in 201 1.
Table 7 201 1 Water Demand by Source (AF)
Urban water demand in 201 1 to the NCMA totaled 4,607 AF of Lopez Lake water, 1,559 AF
of State Water Project water, and 1,169 AF of groundwater. Neither Arroyo Grande, nor
Grover Beach, has a State Water Project allocation. Arroyo Grande has a temporary
agreement to purchase 100 AFY of water from Oceano CSD for the next two years. The
agreement is in its 4th year and is set to expire after 201 3. The 138 AF of "Other Supplies"
Total
2,921.7
1,787.2
1,912.4
851.7
7,473
2,742
38
10,253
Urban Area
Arroyo Grande
Grover Beach
Pismo Beach
Oceano CSD
Urban Water Use
Total
Applied Irrigation
Rural Water Users
Total
Lopez
Lake
2,572.37
921.08
1,055.88
57.46
4,606.79
0
0
4,607
State
Water
Project
0
0
809.40
750.00
1,559.40
0
0
1,559
Groundwater
21 1.40
866.13
47.11
44.28
1 ,I 68.92
2,742
38
3,949
Transfers
0
0
0
0
0
0
0
0
Other
Supplies
137.90
0
0
0
137.90
0
0
138
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delivered to Arroyo Grande consists of groundwater pumped from the Pismo Formation,
which is located outside of the shared groundwater basin.
Based on the estimated groundwater safe yield, the total available supply for all uses is
15,748 AFY, which is the sum of 10,769 AFY for urban plus the allocation for applied
irrigation and rural area of 4,979 AFY. Total applied water demand by source was estimated
at 10,253 AFY for 201 1.
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6 Manaaement Activities
Section 6 is divided into two parts: the first section presents the primary NCMA groundwater
management objectives and summarizes major historical management activities relevant to
the objectives. The second section describes management activities in 201 1.
The group of NCMA groundwater users involved in the stipulation, the Northern Parties,
comprises the Northern Cities, the overlying owners, San Luis Obispo County and San Luis
Obispo County FC&WCD have actively managed surface water and groundwater resources
for more than 30 years. Management objectives and responsibilities were first established the
1983 Gentlemen's Agreement and updated in the 2002 Settlement Agreement. The
responsibility and authority of the Northern Parties for NCMA groundwater management
was formally established through the 2002 Settlement Agreement, 2005 Stipulation, and
2008 Judgment. The overall management goal for the Northern Cities is to preserve the
long-term integrity of water supplies in the NCMA portion of the Santa Maria Groundwater
Basin (SMGB).
6.1 Management Objectives
Seven basic objectives have been established for ongoing NCMA groundwater management.
Under each objective, the NCMA technical group has identified a number of strategies to
meet the objectives. These strategies are shown under each of the seven objectives listed
below:
1. Share Groundwater Resources and Manage Pumping
Continued reduction of groundwater pumping, maintain below safe yield.
Coordinated delivery of Lopez Lake surplus water to maximize surface water
supplies.
o Transfer of Lopez Lake surplus water between Oceano CSD and Arroyo
Grande.
o Temporary purchase of 100 AFY of water by Arroyo Grande from Oceano
CSD, which expires after 2013.
Continue to import State Water Project supplies to Oceano CSD and Pismo
Beach.
Performed capacity assessments on the Lopez Lake and Coastal Branch pipelines
to allow maximum current and future surface water imports.
Performed pigging on the Lopez Lake pipeline to increase delivery capacity.
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Maintain surface water delivery infrastructure to maximize capacity.
o 18" Lopez Lake Pipeline Pigging Project
o 33" Lopez Lake Pipeline Pigging Project
2. Monitor Supply and Demand and Share Information
Share monthly groundwater pumping data at NCMA TG meetings.
Evaluate future water demands through comparison to UWMP projections.
o Arroyo Grande 20 10 UWMP
o Pismo Beach 2010 UWMP
o Grover Beach 20 10 UWMP
3. Manage Groundwater Levels and Prevent Seawater Intrusion
Utilize of storm-water ponds to capture storm-water run-off and recharge the
groundwater basin.
Install transducers in key monitoring wells to provide continuous groundwater
elevation data; the following wells have transducers:
o 24B01
o 24B03
o 30F03
o 30N02
o County Monitoring Well #3
Collect and evaluate daily municipal pumping data to determine impact on local
groundwater elevation levels.
= Coordinate with FC&WCD to install a transducer in the new County Monitoring
Well #3 on the NCMAMMA boundary.
Coordinate pursuit of IRWM Planning and LGA grant funding to characterize the
SMGB and develop a groundwater flow model.
4. Protect Groundwater Quality
Perfom additional water quality monitoring at new County Well #.3
Install temperature and electrical conductivity probes in 5 monitoring wells to
continuously track water quality indicators for seawater intrusion.
Characterize groundwater basin in preparation for the development of a Salt and
Nutrient Management Plan.
Investigate using recycled water in a seawater intrusion barrier.
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5. Manage Cooperatively
Include the Santa Maria Valley Management Area (SMVMA) in the Santa Maria
Groundwater Basin Management Areas (SMGB MA) Technical Subcommittee.
Coordinate groundwater monitoring data sharing and annual report preparation
with the NCMA, NMMA and the SMVMA.
6. Encourage Water Conservation
Share updated water conservation information
Implement UWMPs
7. Evaluate alternative sources of new developed water (Stipulation Section IV)
Addressed through importation of additional SWP supplies and expanded use of
recycled water
Analyze capacity of the Lopez Lake and Coastal Branch pipelines to maximize
deliveries of surface water. For example:
o Lopez Lake Pipeline Capacity Evaluation
o Lopez Lake Pipeline Capacity Re-Evaluation
o Coastal Branch Capacity Assessment
The history and rationale are discussed in the sections below. Other potential objectives are
outlined in the final section.
6.1.1 Share Groundwater Resources and Manage Pumping.
A longstanding objective of water users in the NCMA has been to cooperatively share and
manage groundwater resources. In 1983 the Northern Parties mutually agreed on an initial
safe yield estimate (defined by DWR) and an allotment of pumping between the urban users
and applied irrigation users of 57 percent and 43 percent respectively. In this agreement the
Northern Cities also established pumping allotments among themselves. Subsequently the
2002 Settlement Agreement included provisions to account for changes such as land
conversion. The agreements provide that any increase or decrease in the safe yield based on
ongoing assessments would be shared on a pro rata basis. Pursuant to the stipulation the
Northern Cities conducted a water balance study to update the safe yield estimate (Todd
Engineers 2007). Among other results, the parties agreed to maintain the existing pumping
allotment among the urban users and established a consistent methodology to address
agricultural land use conversion.
In addition to cooperatively sharing and managing groundwater resources, the Northern
Cities have coordinated delivery of water from Lopez Lake, and have continued to import
SWP water to maximize use of available surface water supplies. A total of 100 AFY of
Lopez Lake entitlement, or groundwater allotment, is made available for Arroyo Grande to
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purchase from Oceano CSD via a temporary purchase agreement. Oceano CSD and Pismo
Beach continue to import SWP water. These activities have allowed the Northern Cities, as a
whole, to reduce the amount of groundwater that is pumped from the shared basin.
Along with coordination activities to maximize surface water supplies, the Northern Cities
have performed capacity assessments on the Lopez Lake and Coastal Branch pipelines to
maximize current and future surface water imports. A portion of the Lopez Lake pipeline has
been "pigged" (a cleaning and maintenance procedure) to increase delivery capacity as well.
The water balance study also highlighted the threat of seawater intrusion as the most
important potential adverse impact to consider in managing the basin. Seawater intrusion, a
concern since the 1960s, would degrade the quality of water in aquifer and potentially render
portions of the basin unsuitable for groundwater production (DWR 1970).
Another potential adverse impact of localized pumping includes reduction of flow in local
streams, notably Arroyo Grande (Todd Engineers 2007). The Northern Cities (as Zone 3
contractors) have participated with FC&WCD in preparation of the Arroyo Grande Creek
Habitat Conservation Plan (HCP) that addresses reservoir releases to maintain both
groundwater levels and habitat diversity in the creek.
6.1.2 Monitor Supply and Demand and Share Information
Regular monitoring of activities that affect the groundwater basin, and sharing that
information, has occurred for many years. Monitoring includes gathering data on hydrologic
conditions, water supply and demand, and groundwater pumping, levels, and quality. This
was first established in 1983 and then formalized in 2002 to include quarterly meetings. The
current monitoring program is managed by the Northern Cities in accordance with the 2005
Stipulation and 2008 Judgment, guided by the July 2008 Monitoring Program for the NCMA.
The data and its implication to groundwater management are summarized in the Annual
Reports. Arroyo Grande, Grover Beach, and Pismo Beach have each evaluated their future
water demands as part of their respective 2010 UWMP updates. The NCMA has engaged the
two other management areas and now shares information through data exchange and regular
meetings throughout the annual report preparation cycle.
6.1.3 Manage Groundwater Levels and Prevent Seawater Intrusion
Prevention of seawater intrusion through the management of groundwater levels is essential
to protecting the shared resource. While closely related to the objectives to manage
pumping, monitor supply and demand, and share information, this objective specifically
recognizes the proximity of production wells to the coast and the threat of seawater intrusion.
The Northern Cities, County and FC&WCD have long cooperated in the monitoring of
groundwater levels, including quarterly measurement of groundwater levels in the sentry
wells at the coast. Upon assuming responsibility for the coastal monitoring wells, the
NCMA became aware of the need to upgrade their condition. In July 2010 the well-heads
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(surface completions) at four sentry monitoring well clusters within the Northern Cities
Management Area were renovated (Todd Engineers 20 10). The modifications occurred at
well clusters:
32S112E-24B0 I, B02, B03
The renovations included raising the elevations of the top of each individual well casing by
two to three feet in order to reduce the risk of surface water entering the wells. Because the
top of the well casing is used as the reference point for all depth to water measurements, the
new surface completions were surveyed relative to the NAVD 88 standard in late September
2010 (Wallace Group 2010). (Changes in the wellhead elevations are indicated in Tables 6A
and 6B.) 'The individual well casings have been raised above ground surface and protective
locking steel risers now enclose each cluster. As a result of this work, the sentry wells within
the NCMA are now protected from surface contamination and tampering.
While quarterly measurement of groundwater levels aids in assessing the risk of seawater
intrusion along the coast, the NCMA has installed transducers in 5 monitoring wells to
provide continuous groundwater levels at key locations. By combining this with the
collection and evaluation of daily municipal pumping data, the NCMA hopes to be able to
determine the response of local groundwater levels to extractions and therefore better manage
the basin.
As a result of lowering of water levels during 2007 and 2008, the Northern Cities reduced
pumping from the basin and requested increased SWP deliveries. This response has allowed
groundwater levels to rise to a level apparently sufficient to prevent seawater intrusion (see
Section 4.2 of this report).
6.1.4 Protect Groundwater Quality
'The objective to protect groundwater quality is closely linked with the objective for
monitoring and data sharing. To meet this objective all sources of water quality degradation,
including the threat of seawater intrusion, need to be recognized. Water quality problems
could affect the integrity of groundwater supplies, resulting in loss of use or expensive water
treatment processes. Sentry wells are monitored quarterly and data from other NCMA
production wells are assessed annually. The monitoring program includes evaluation of
potential contaminants in addition to those that might indicate seawater intrusion.
Temperature and electrical conductivity probes have been installed in 5 monitoring wells to
provide continuous water quality tracking for early indication of seawater intrusion. For
example, local nitrate and selenium concentrations in excess of primary drinking water
standards have been addressed through actions such as provision of municipal water to
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private domestic users and through nitrate removal or blending to ensure that delivered water
meets all drinking water standards. Additionally, the groundwater basin is being
characterized in preparation for the possible development of a Salt and Nutrient Management
Plan.
6.1.5 Encourage Water Conservation
Water conservation, or water use efficiency, is linked to the monitoring of supply and
demand and the management of pumping. Water conservation would reduce overall demand
on all sources, including groundwater, and support management objectives to manage
groundwater levels and prevent seawater intrusion. In addition water conservation is
consistent with State policies seeking to achieve significant water use reductions by the year
2020. Water conservation activities in the NCMA are summarized in various documents
produced by the Northern Cities, including the 201 0 Urban Water Management Plans of
Arroyo Grande, Grover Beach, and Pismo Beach.
6.1.6 Manage Cooperatively
Since 1983, NCMA management has been based on cooperative efforts of the affected
parties themselves including the four Northern Cities with ongoing collaboration with San
Luis Obispo County, the FC&WCD, and other local and state agencies. Other organizations
participate as appropriate to the issues of the time. In addition to the efforts discussed in the
report, cooperative management occurs through many means including communication by
the Northern Cities in their respective public meetings and participation in the Water
Resources Advisory Council (the County-wide advisory panel on water issues).
The NCMA agencies participated in preparation and adoption of the 2007 San Luis Obispo
County Integrated Regional Water Management Plan (IRWMP). The IRWMP promotes
integrated regional water management to ensure sustainable water uses, reliable water
supplies, better water quality, environmental stewardship, efficient urban development,
protection of agriculture, and a strong economy. The IRWMP integrates all of the programs,
plans, and projects lead by entities within the region into water supply, water quality,
ecosystem preservation and restoration, groundwater monitoring and management, and flood
management programs. The IRWM Plan ,is in the process of being revised and NCMA
agencies are participating.
6.1.7 Other Potential Management Objectives
Based on information developed in preparation of this Annual Report and other management
activities (discussed in Section 6.2), it may be appropriate to develop other management
objectives to address:
Optimizing sources to best provide for prolonged droughts (Todd Engineers 2007)
Optimizing location and rate of groundwater pumping to protect groundwater quality
(Todd Engineers 2007)
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= Calculating target gradient to prevent seawater intrusion (Miller and Evenson 1966)
Assessing basin response to recharge and use based on drought cycle
6.2 Update on Management Activities
The Northern Cities, both individually and jointly, are engaged in water resource
management projects, programs, and planning efforts that address water supply and demand
issues, particularly efforts to assure a long-term sustainable supply. This section discusses
major management activities during 201 1. These management activities, taken as a whole,
address all of the Management Objectives described in Section 5.
6.2.1 Expansion of Groundwater Monitoring
Groundwater monitoring has been expanded in order to address objectives relating to
managing groundwater levels and preventing seawater intrusion, protecting groundwater
quality, and managing pumping. In 2009 the sentry well monitoring program was intensified
to include quarterly water quality sampling and analysis. A project to renovate the sentry
wells also was initiated. In July 201 1 the tops each piezometer casing in the sentry well
locations were raised above land surface to avoid the potential of surface runoff entering the
casing. In addition the protective well casing was modified to prevent tampering. Each
modified well was resurveyed relative to the North American Vertical Datum (NAVD) 88.
In 201 1 continuous monitoring equipment was installed in three deep sentry wells and one
shallow well to gather data on short term water level fluctuations potentially caused by tidal
influences and groundwater extractions. Continuous monitoring equipment will be installed
in a newly constructed well in 2012 to measure water level and electrical conductance
changes on the southern edge of the NCMA.
6.2.2 Control of Groundwater Levels and Seawater Intrusion
The Northern Cities that may accept SWP deliveries have requested a one-time augmentation
of their allocation. Continuing importation of State Water project supplies will allow the
users in NCMA to reduce groundwater demand. This allows the County to store up to 1500
AF of emergency water to reduce coastal seawater intrusion, and also allows the County to
store water in Lopez Lake for future emergency use. In addition, each of the Northern Cities
was able to reduce its groundwater use below its safe yield allotment in 201 1.
6.2.3 Cooperative Water Supply Planning and Management
Water supply planning and management activities in 201 1 included an ongoing water supply
agreement between Arroyo Grande and Oceano CSD, ongoing recharge using storm water
detention ponds, sentry well monitoring, data sharing, regional agreements, implementation
of additional water conservation measures, and ongoing studies to acquire new water supply
sources. Pursuant to State law, three of the NCMA members prepared Urban Water
Management Plans that document current supply and demand as well as project future supply
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and demand. In addition, Oceano CSD is in the process of completing its Water and Sewer
Master Plan that details their water system and provides water shortage contingency plans.
Water Transfer
In January 2009, Arroyo Grande entered into temporary agreement with Oceano CSD to
purchase an additional 100 AFY of supplemental water supply. This agreement will expire
after 2013.
Storm Water Ponds
Arroyo Grande, Grover Beach, and Oceano CSD each maintain storm water retention ponds.
These ponds collect storm water runoff, allowing it to recharge the underlying aquifers.
There are approximately 140 acres and 48 acres of detention ponds in Arroyo Grande and
Grover Beach, respectively. The existing storm water detention pond in Oceano CSD is
approximately half an acre. Grover Beach recently modified its storm water system to direct
additional flow into one of its recharge basins. San Luis Obispo County is currently
evaluating creation of a 50-acre storm water detention pond near the Oceano Airport. This
pond would also create an opportunity for recharge to the groundwater basin. The Oceano
Drainage and Flood Control Study documents the need for such a pond and identifies the
steps required to implement the facility.
Data Sharing
The Northern Cities cooperate with San Luis Obispo County and the Nipomo Mesa
Management Area (Nh4MA) in the improvement of regional groundwater monitoring.
Consistent with state Law, 3 NCMA cities have adopted updated UWMPs to include 2010
data, projections of supply and demand as well as estimates of daily per capita demand.
During preparation of each Annual Report, the Northern Cities and NMMA also share water
quality data and collaborate on the interpretation of groundwater level data and preparation
of water elevation contour maps.
6.2.4 Water Conservation
The Northern Cities implement water conservation activities to reduce water use and thus
reduce groundwater demand. The Cities participate in a wide range of water conservation
activities designed to educate the public on ways to reduce water use.
City of Arroyo Grande
The City of Arroyo Grande supports a part time water conservation coordinator staff position
to manage existing conservation activities, encourage public participation, and create new
conservation programs for the community. In the last eight years, Arroyo Grande spent over
$1,000,000 on water conservation efforts. Arroyo Grande is implementing the following
water Demand Management Measures (DMMs):
Water Survey Programs (Equivalent program elements)
Residential Plumbing Retrofits
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Water System Audits
Metering with Commodity Rates
Large Landscape Irrigation Programs
High-efficiency washing machine rebate programs
Public information programs.
School education programs.
Conservation programs for commercial, industrial, and institutional accounts.
Conservation pricing.
Water conservation coordinator.
Water waste prohibition.
Residential ultra-low-flush toilet replacement programs.
Cash for Grass
The water conservation efforts of Arroyo Grande have been very successful to date; the
DMMs that have been implemented have decreased water use per residential connection
from 190 gpcd to 156 gpcd. The target per capita usage for 201 5 is 167 gpcd, while the target
per capita usage for 2020 is 149 gpcd. Continued implementation of these BMPs will help
Arroyo Grande to reach its per capita water use goals and indicates the commitment Arroyo
Grande has to optimizing use of its water supply. Arroyo Grande is developing a program to
evaluate the effectiveness of the water conservation program pursuant to Water Code Section
10631 (g).
City of Pismo Beach
'The City of Pismo Beach is a member of the California Urban Water Conservation Council,
and as such has developed best management practices (BMPs) to reduce water consumption
and ensure reliable future water supply. Included in BMPs implemented by Pismo Beach are
activities and programs that promote water conservation and sustainable use of water
resources. BMPs that Pismo Beach is implementing or has equivalent coverage are:
Water Survey Programs
Residential Plumbing Retrofit
Water System Audits
Metering with Commodity Rates
Landscape Lrrigation Programs
Conservation Pricing
Water Conservation Coordinator
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Ultra Low Flush Toilet Replacement
The water conservation efforts of Pismo Beach have helped reduce residential water use from
a high of 256 gpcd in 2007, to 226 gpcd in 2010. The 1 O-year baseline average water use is
236 gpcd. Continued implementation of these BMPs and implementation of other BMPs in
the future will help Pismo Beach reach its per capita water use goals and indicates the
commitment of Pismo Beach to optimizing use of its water supply. The target water use for
2015 is 2 14 gpcd, while the target water use for 2020 is 192 gpcd.
City of Grover Beach
As described in their 2010 Urban Water Plan, Grover Beach has developed and implemented
Demand Management Measures to reduce water consumption and ensure reliable future
water supply. Included in the DMMs implemented by the Grover Beach are activities and
programs that promote water conservation and sustainable use of water resources. DMMs
that Grover Beach is implementing or has equivalent coverage are:
Water survey programs for single-family residential and multifamily residential
customers
Residential plumbing retrofit
System water audits, leak detection, and repair
Metering with commodity rates for all new connections and retrofit of existing
connections
Large landscape conservation programs and incentives
High-efficiency washing machine rebate programs
Public information programs
School education programs
Conservation programs for commercial, industrial, and institutional accounts
Conservation pricing
Water conservation coordinator
Water waste prohibition
Residential ultra-low-flush toilet replacement programs
Grover Beach has implemented or is planning to implemeit all applicable demand
management measures as part of the Water Conservation Program. The ongoing water
conservation activities of Grover Beach include a "Cash for Grass" rebate, a water-efficient
washing machine rebate program, and smart irrigation controller and sensor rebate program.
'The 10-year baseline average water use for Grover Beach is 140.7 gpcd. The target water
use for 2015 is 127 gpcd, while the target water use for 2020 is 1 13 gpcd.
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6.2.5 Alternative Water Supply Studies
The Northern Cities continue to evaluate alternative sources of water supply which could
provide a more reliable and sustainable water supply for the NCMA. An expanded portfolio
of water supply sources will support sustainable management of the groundwater resource
and help to reduce the risk of water shortages. These alternative sources include:
State Water Project
As discussed above, the Northern Cities have requested a short-term allocation of 1,500 AF
for the NCMA. Oceano CSD and Pismo Beach are currently SWP customers and could use
additional water immediately. Grover Beach is not a SWP customer; however, Grover Beach
could indirectly benefit from the water assuming that the allocation is granted. If successful,
a longer tern allocation could be evaluated based on the existing FC&WCD allotment from
the SWP.
Water Recycling
In 2010, the South San Luis Obispo County Sanitation District (SSLOCSD) updated their
2001 evaluation of recycled water opportunities. The new evaluation included an evaluation
of using disinfected secondary treated water to irrigate landscaping and the potential use of
recycled water if the SSLOCSD waste water treatment plant were upgraded to provide
tertiary treatment. By providing tertiary treatment up to 189 AFY of potential demand could
be satisfied.
The City of Pismo Beach also has evaluated use of recycled water. As described in their
20 1 0 UWMP, "the City may begin regional planning efforts regarding recycled water within
the nextJve years ". The City of Pismo Beach is considering plans to upgrade its waste water
treatment plant to provide an anticipated recycled water supply of up to an estimated 1,558
AFY in 2015. This estimate provides an idea of the amount of recycled water that could be
available. The City of Pismo Beach UWMP anticipates that the recycled water not used for
irrigation near the WWTP and in the Price Canyon development area "may be applied
towards groundwater recharge operations."
Lopez Lake Expansion
In 2008, San Luis Obispo County sponsored a preliminary assessment of the concept of
installing an inflatable rubber dam at the Lopez Dam spillway. The NCMA is in the process
of completing an assessment of dam safety, evaluation of project benefits (including
identification of participating parties), identifying alternatives, engineering feasibility studies,
environmental review, permitting, design, and construction.
Desalination
In 2006, Arroyo Grande, Grover Beach, and Oceano CSD utilized Prop 50 funds to complete
a feasibility study on desalination as an additional water supply option for the NCMA. This
alternative supply is not considered to be a viable option at this time.
Agenda Item 11.a.
Page 52
FINAL REPORT
2011 ANNUAL MONITORING REPORT
NORTHERN CITIES MANAGEMENT AREA
Nacimiento Pipeline Extension
In 2006, Arroyo Grande, Grover Beach, and Oceano CSD completed a Nacimiento pipeline
extension evaluation to determine the feasibility of delivery water from the Nacimiento
reservoir to the NCMA. This alternative supply is not considered to be a viable option at this
time.
Agenda Item 11.a.
Page 53
FINAL REPORT
2011 ANNUAL MONITORING REPORT
NORTHERN CITIES MANAGEMENT AREA
7 References Cited
California Department of Water Resources. 1970. Sea-Water Intrusion: Pismo-Guadalupe
Area. Bulletin No. 63-3,76 p.
California Department of Water Resources. 2002. Water resources of the Arroyo Grande -
Nipomo Mesa area: Southern District Report, 156 p.
Carollo Engineers. 201 1. City of Pismo Beach 2010 Urban Water Management Plan.
City of Arroyo Grande. 2010. City of Arroyo Grande 201 0 Urban Water Management Plan.
City of Grover Beach. 2010. City of Grover Beach 2010 Urban Water Management Plan
EDAW, Inc. August 1998. San Luis Obispo County Master Water Plan Update.
GEI Consultants. 20 1 1. 20 10 Annual Monitoring Report, Northern Cities Management area.
GEI Consultants. April 201 0.
Miller, G. A. and Evenson, R. E. 1966. Utilization of Groundwater in the Santa Maria Valley
Area, California. USGS Water Supply Paper 18 19-A.
NMMA Technical Group. 201 1. Nipomo Mesa Management Area, 2nd Annual Report,
Calendar Year 2010.
Superior Court of California, County of Santa Clara, in Judgment Afier Trial, entered January
25,2008 incorporating 2002 Settlement Agreement among the Northern Cities, Northern
Landowners, and Other Parties, and 2005 Settlement Stipulation for the Santa Maria
groundwater basin adjudication.
Todd Engineers. 2007. Water Balance Study for the Northern Cities Area. Todd Engineers.
April 2007.
Todd Engineers. 2010.2009 Annual Monitoring Report, Northern Cities Management area.
Todd Engineers April 20 10.
Todd Engineers. 201 0. Summary of Renovations for the Northern Cities Management Area
Sentry Wells, San Luis Obispo County, California
Wallace Group, 2010. Survey Report on the "Sentry" Well Elevation Establishment for
Cities of Arroyo Grande, Grover Beach, Pismo Beach and the Oceano Community Services
District
Agenda Item 11.a.
Page 54
_ _- L a Adjudlcal~on Area Boundary I
I
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4 2 0 4 2011 Annual Mon~lor~ng Report
San Lus Ob~spo and Santa Barbara Counl~es
M~les Northern C~t~es Management Area
1 SANTA MARIA RIVER VALLEY 1 GROUNDWATER BASIN
I APRIL 2012 FIGURE 1
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2011 Annual Monitoring Report
Northern Cities Management Area
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2011 Annual Monitoring Report
Northern Cities Management Area
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Agenda Item 11.a.
Page 58
Arroyo Grande
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Northern C~l~es Managemenl Area
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Northern Cities Management Area
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San LUIS Oblspo. Cal~lorn~a
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Northern C~tres Manaqement Area GEI ' MARCH 2012 FlGUl Agenda Item 11.a.
Page 61
Figure 8 - Depths of Sentry Wells
OCSD Observation
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Northern Cities Management Area
rq G E I .-' '!
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Page 63
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2011 Annual Monitoring Report
Northern C~t~es Manaqement Area
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APRIL 2012 FIGURE 99 Agenda Item 11.a.
Page 64
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LEGEND .I I
4
2011 Annual Moniloring Report Selected Well Hydrographs
Norlhern Cllies Managemenl Area Figure 10
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201 1 ANNUAL MONITORING REPORT
NORTHERN CITIES MANAGEMENT BREA
SENTRY WELL HYDROGRAPHS
MARCH 2012 FIGURE 11
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and 30N (See Flgure 7 for locat~ons
and F~gure 8 for Sentry Well Depths)
2011 Annual Monitoring Report
Northern Cities Management Area GEIc >!
Hydrograph of Average Deep Sentry Well Elevations
May2012 Figure 12A
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2011 ANNUAL MONITORING REPORT WATER ELEVATION, CONDUCTIVITY,
AND TEMPERATURE, WELL 24801
Norlhern Cit~es Manaaement Area FIGURE 12B
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2011 ANNUAL MONITORING REPORT WATER ELEVATION, CONDUCTIVITY,
GEI. AND TEMPERATURE, WELL 30N02
Norlhem C~t~es Manaqernent Area APRIL 2012 FIGURE 12E
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LEGEND
+ Sele d Well
2011 Annual Mon~lonng Report
El
Chlor~de Concenlral~ons Over lime In Senlry Wells
Norlhern C~lles Management Area GEI May 2012 Ftgure 13
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2011 Annual Mon~tonng Report
I
Total Dissolved Sol~ds Concenlrat~ons Over Time In Sentry Wells
Norlhem C~l~es Managemenl Area F~gure 14
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Figure 15 - Schoeller Diagram for Sentry Well 30N02, 2010-2012
201 1 ANNUAL MONITORING REPORT
NORTHERN CITIES MANAGEMENT AREA
rT GEI
SCHOELLER DIAGRAM FOR SENTRY WELL 30N02
2010 - 2012
MAY 201 2 FIGURE 15
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