HomeMy WebLinkAbout; Proposed Revision Basin Plan Objectives; Hydrology Report; 1980-11-02 (2)PROPOSED REVISION BASIN PLAN OBJECTIVES
A PORTION OF THE AGUA HEDIONDA HYDROGRAPHIC SUBAREA
ENGINEERING DEPT. LIBRARY City of Carisbad
2075 Las Palmas Drive
Carlsbad CA 92008-4859
November 2, 1980
ENGINEERING DEPT. LIBRARY City of Carlsbad
2075 Las Palmas Drive Carlsbad, CA 92009-4859
LUKE-DUDEK, Civil Engineers
700 Second Street
Encinitas, California Suite E
7141942-5147
TABLE OF CONTENTS
CHAPTER
1. IDENTIFICATION OF STUDY AREA ................. 1
A. Introduction ............................. 1
2. LAND USE ..................................... 3
A. Introduction ............................. 3 B. 1968 Land Use ............................ C. 1980 Land Use ............................ 6 D. 2000 Land Use ............................ 6
3. DESCRIPTION OF BENEFICIAL USES OF GROUND- WATER IN THE STUDY AREA ..................... 11
A. Past Beneficial Uses .................... 11 B. Present Beneficial Uses ................. 11 C. Future Beneficial Uses .................. 12
4. DESCRIPTION OF GROUND AND SURFACE WATER QUALITY ..................................... 14
A. Historic Groundwater Quality ............ 14 B. Present Groundwater Qualtiy ............. 18 C. Future Groundwater Quality .............. 20 1. Introduction ........................ 20
2. Summary of Geohydrologic Conditions
3. Groundwater Recharge 23 Agua Hedionda Basin 21
5. Effects of a Reclamation Program.. . .30
................. ................ 4. Future Groundwater Quality .......... 29
D. Surface Water Qualtiy ................... 30
5. DESCRIPTION OF REQUESTED CHANGES ............ 33
A. Introduction ............................ 33
6. DEMONSTRATIONS OF CONSISTENCY BETWEEN THE REQUESTED AND THE STATE'S NONDEGRADATION POLICY ...................................... 37
A. Introduction. ........................... 37 B. Summary of State's Nondegradation Policy ................................... 37 C. Implications of the Requested Changes to the Groundwater Objectives for the Study Area .......................... 3 8.
TABLE OF CONTENTS (Cont'd)
CHAPTER
6. CONT ' D
PAGE -
D. Population Group 1 - Existing and Potential Groundwater Users ............ 39 1. Evaluation of Economic Benefit vs Detriments for the Group 1 Population ......................... 40
Detriment for the Group 1 Population 41
Uses of Reclaimed Water ................ 42 1. Economic Benefits vs Detriment for the Group 2 Population ......... 44 2. Social Benefits vs Detriment for the Group 2 Populations 44
2. Evaluation of Social Benefit vs
......................... E. Population Group 2 - Potential
............ F. Population Group 3 Residents Within the Costa Real Water District and City of Oceanside ...................... 45 1. Economic Benefit vs Detriment
2. Social Benefits vs Detriment for Group 3 Population ............. 46
for the Group 3 Population ......... 46 G. Administrative Considerations .......... 47 H. Summary ................................ 49
LIST OF TABLES
TABLE
2- 1
-
2-2
4- 1
4- 2
4- 3
4- 4
5- 1
5-2
6- 1
6- 2
6- 4
PAGE -
Land Use Acreage Estimates for the Study Area .................................. 5
Population Estimates for the Study Area ........................................ 5
Agua Hedionda Hydrologic Subarea (4.31) Historical Well Sampling Data ....... 15
Agua Hedionda Subarea (4.31) Recent Well Sampling Data ......................... 19
Estimated Underdrainage to the Agua Hedionda Groundwater Basin 1980 Conditions ................................. 28
Agua Hedionda Hydrographic Subarea (4.31) Surface Water Sampling Data ......... 32
Agua Hedionda Hydrographic Subunit 34 Groundwater Quality Objectives for the
Proposed Groundwater Quality Objectives for the Study Area (Lower Agua Hedionda Hydrographic Subarea) ...................... 36
Economic Benefit vs Detriment for Group 1 Population Caused by Easing Groundwater Objectives ................................. 41
Potential Users of Reclaimed Water ......... 43
.Energy Saving of Reclaimed Water Progr am... 48
.........
LIST OF FIGURES
FIGURES PAGE -
1- 1 Study Area ..................... 2
2-1 Past Land Use (1968) ........... 8
2-2 Present Land Use (1980) ........ 9
2- 3 Future Land Use (2000) ........ 10
4- 1 Sampling Locations ............ 16
4- 2 Hydrogeologic Representation Lower Agua Hedionda Drainage Basin ......................... 22
CHAPTER 1
IDENTIFICATION OF STUDY AREA
A. Introduction
The study area boundary is shown in Figure 1-1.
It lies within the lower portion of Agua Hedionda Subarea
(4.31) of the Agua Hedionda Subunit of the Carlsbad Hydro-
graphic Unit, as defined by the "Comprehensive Water
Quality Control Plan Report San Diego Basin 9," (Basin
Plan), prepared for the State Water Resource Control Board
and the San Diego Regional Water Quality Control Board
in 1975. Drainage within Subarea 4.31 flows to Agua Hedionda
Creek which then empties into Agua Hedionda Lagoon. The
portion of Subarea 4.31 for which groundwater objectives
revision is proposed would encompass those areas tributary
to Agua Hedionda Creek downstream from its intersection with
El Camino Real. Not included are those areas tributary
to Macario Canyon, located southerly of Evans Point, those
areas directly south of Agua Hedionda Lagoon and those areas
west of Interstate 5 within Subarea 4.31. The study area
is downstream of Sintorosa Country Club, and located partial-
ly within the corporate boundary of the City of Carlsbad, and
some privately owned portions of the County of San Diego
known as Rancho Agua Hedionda.
These boundaries were chosen to preclude any inter-
ference with areas upstream where several existing domestic
and agricultural wells are presently in use.
CHAPTER 2
A. Introduction
The study area located in the lower Agua Hedionda
drainage basin is located almost entirely within the Carls-
bad city limit, with a small portion in the southeast corner
inside the County of San Diego boundary. The area north and
east of the Agua Hedionda Lagoon has been marked in the last
decade by a rapid conversion from undeveloped-rural land use
to urban development. The area directly east of the Lagoon,
however, has retained its rural character mainly because the
land belongs to a single rancher. Land use projections pre-
dict these areas will be completly urbanized within the next
10 to 20 years.
Agricultural activities will gradually lose ground
to urban development. In its place open space areas are
planned to maintain the natural aesthetic qualities of the
landscape. Irrigation of the open space corridors with re-
claimed water will further enhance the verdant qualities of
the area.
An estimation of the land use acreages for years
1968, 1980 and 2000 have been compiled for the study area,
and listed in Table 2-1. Population and dwelling unit data
are listed in Table 2-2 for the same years based on the
San Diego Comprehensive Planning Organization's figures.
Land use acreages were taken from information provided by
the U.S. Geologic Survey, City of Carlsbad, San Diego Com-
prehensive Planning Organization and aerial photographs.
Because some of the land use data is conflicting, a rational
estimate of each land use boundary was determined.
Three land use classifications are shown for this
study. These are: urban areas, including commercial, in-
dustrial and sewered residential zones, agricultural areas
and open space areas. The latter land use type includes all
undeveloped lands, parks, golf courses, sparsely populated
rural areas (sewage disposal by septic tanks) and those por-
tions of Aqua Hedionda Lagoon within the study area.
B. 1968 Land Use
The 1968 land use acreages were estimated from the
U.S. Geologic Survey, 15-minute, San Luis Rey quadrangle,
dated 1968, and from aerial photographs. The locations of
each land use type for 1968 are shown in Figure 2-1.
Urban areas amount to 592 acres within the study
area, all part of the City of Carlsbad. Agricultural areas
comprise 545 acres and open space makes up the remaining
1463 acres. The study area has a total of 2,600 acres.
As can be seen from Table 2-1 and Figure 2-1, the
majority of land within the study area was open space in
1968. Urbanization was spreading from the City of Carlsbad
easterly and southerly toward El Camino Real and Agua
Hedionda Lagoon. Population figures for 1968 are 4,966
persons and 1,986 dwelling units (DU) based on 2.5 persons
per DU.
The agricultural area was quite extensive in 1968.
A majority of the 545 acres involved in agricultural activ-
ities was located east of El Camino Real along small water
courses tributary to Agua Hedionda Creek. Field crop agri-
culture existed south of Agua Hedionda Creek on Kelly
property, and just north of Agua Hedionda Lagoon. Irrigation
of field crops generally came from the local surface water
drainage courses, some dauned for storage, and from shallow
wells in the area. Approaching urbanization was thought to
be the greatest danger to existing agricultural activities.
TABLE 2-1 Land Use Acreage Estimates for the Study Area
YEAR URBAN (acres) AGRICULTURAL (acres) OPEN SPACE (acres)
1968
1980
2000
592
1,160
2,110
5 45
440
0
1,463
1,000
490
TABLE 2-2 Population Estimates for the Study Area*
YEAR POPULATION DWELLING UNITS
1968
19 80
2000
4.966
6,601
10,428
1,986
2,640
4,171
*Based on extrapolated data from the Comprehensive Planning Organization Series IV-B Projections, and excluding those areas west of Interstate 5.
C. 1980 Land Use
The 1980 land use acreages were estimated from the
U.S. Geological Survey, 1968 San Luis Rey 15-minute quad-
rangle (photorevised 1975), and from recently shot aerial
photographs of the study area. The locations of each land
use type for 1980 are shown in Figure 2-2.
Those areas classified as urbanized in 1968 have
grown to 1,160 acres in 1980. Agricultural and open space
areas have shrunk to 440 and 1,000 acres, respectively.
Urban land use has become the major land use type in 1980.
Developed areas have continued to expand eastward up to and
beyond El Camino Real, as well as along the areas north of
Agua Hedionda Creek. No urbanization has yet expanded south
of the Creek on Kelly Ranch property. Some agricultural
lands have been urbanized west of El Camino Real. Open space
areas have been urbanized north of the Agua Hedionda Lagoon.
Population figures for 1980 are 6,601 persons occupying
2,640 DUs.
Agricultural lands east of El Camino Real and south
of Agua Hedionda Creek have remained essentially the same
as in 1968. Some open space has been developed on either
side of El Camino Real and north of the Lagoon and Creek.
D. 2000 Land Use
Land use estimates for the year 2000 in the lower
Agua Hedionda basin is based on the City of Carlsbad's
"Land Use Plan" and on development trends evident in past
and present land use figures. This Plan represents the
expected land use in the City of Carlsbad at some future period
of time at "total Saturation". Based on existing trends in
this area, we expect total saturation to occur before the
year 2000 within the corporate boundaries of the City of
Carlsbad. This includes a majority of the study area at
present.
As in the lower Buena Vista basin, directly north
of lower Agua Hedionda basin, urbanization will have extended
across the entire study area shown in Figure 2-3. Small
areas of open space along Agua Hedionda Creek and Lagoon,
as well as the canyons located in the northeast portion of
the study area, will be spared from development for the
enjoyment of the population at that time. It is estimated
that no major agricultural acreages will remain in the year
2000, only small family orchards and gardens at individual
homesites. Population in year 2000 is expected to reach
10,428 persons in the study area, with 4,171 DUs.
CHAPTER 3
DESCRIPTION OF BENEFICIAL USES OF
GROUNDWATER IN THE STUDY AREA
A. Past Beneficial Uses
A field survey and literature search was conducted
of the study area and vicinity to determine past beneficial
uses of groundwater. Much of the basin is, or has been
owned by the Kelly family for many years.
The relatively low yields and marginal water quality
has limited groundwater use. Past wells produced only suffi-
cient water for domestic use and minimal irrigation or row
crops.
There is evidence from older U.S. Geological Survey
Maps that at least one windmill powered well was located
within the basin. Presumably the basin was tapped for limited
agriculture supply.
As will be discussed more thououghly in Chapter 4,
the transmissivity of the alluvium and sedimentary deposits
is quite low. Historic evidence suggests that most of the
wells drilled in the study area were low yield.
B. Present Beneficial Uses
Currently, only one actively functioning well is
found in the study area known as the Kelly well. This well
is located just downstream of the intersection of Agua Hedionda
Creek and El Camino Real. This well reportedly yields 300
gallons per minute (gpm). Numerous attempts have been made
to drill a productive well further downstream on Kelly property,
however, those attempts have not proved successful. The Kelly
well is used for irrigation of row crops and pasture grasses.
Although accurate water use records are not available,
it is estimated the well produces about 50 acre-feet of water
per year. With water quality varying between 1,300 mg/l to
1,700 mgfl TDS, the water is suitable for irrigation of salt-
tolerant crops, such as tomatoes and pasture grasses.
C. Future Beneficial Uses
The future beneficial uses will be limited by the
basin's relatively poor water quality, limited quantity, and
changing land uses. Chapter 4 projected the water quality
of the basin to slowly degrade to about 2.200 mg/l. It is
improbable that significant degradation will occur before
urban land uses completely dominate the basin. Also, the
study area's only functioning well is located in the upstream
portion of the basin. In this location the well's water
quality is not likely to be significantly degraded by changing
downstream water quality objectives. Thus, the proposed
objective changes are not expected to adversely affect the
beneficial uses of the Kelly well.
With the widespread availability of imported water,
there is no compelling reasons for residents of the area to
use the groundwater for domestic supply. The high TDS violates
the California Department of Health Services' secondary
standards for domestic water. As such, it is highly doubtful
that the Health Department would permit the water to be used
in the future for drinking water. The Costa Real Water District
has no plans to use any water from the study basin.
The aquifer's low yield and high total dissolved
solids will preclude the water from being used on salt-sensitive
agricultural crops. If a severe water shortage should occur,
it is possible that individual homeowners could use the ground-
water on a limited basis for irrigation of landscape or salt-
tolerant pasture grasses.
The groundwater could potentially be used for
industrial service supply in the future, even though the
prospects seem highly unlikely. Since quality is not a
major consideration for this use, any revision of the
groundwater objectives will not prevent this beneficial
use. The basin's low yield probably will discourage any
major future industrial use. During a water shortage the
water could conceivably be used for minor purposes such
as wash-down water at some of the minor commercial
establishments located within the basin.
ENGINEERING DEPT. LIBRARY City of Carlsbad
2075 Las Palmas Drive Carlsbad CA 92009-4859
CHAPTER 4
DESCRIPTION OF GROUNDWATER QUALITY
A. Historic Groundwater Quality
In the 1950's and early 1960's the California
Department of Water Resources (DWR) conducted an extensive
well sampling program within Subarea 4.31. A portion of
the results of this program are shown in Table 4-1, listing
data for calcium (Ca), sodium (Na) , sulfate (SO4), chloride
(Cl), boron (E), total dissolved solids (TDS), nitrates
(NO3) and electrical conductivity (EC).
Of the 14 wells sampled within Subarea 4.31, only
one was located inside the immediate study area, DWR well
No. 12S/4W-9G. This well is designated OW-1 for this report
and its location is shown in Figure 4-1. Well OW-1 was
located in the flood plain along Agua Hedionda Creek just
west of El Camino Real, approximately one mile upstream from
the high water mark of Agua Hedionda Lagoon.
Data from Table 4-1 indicates that groundwater from
Well OW-1 was poor in quality in the early 1960's with a
TDS concentration averaging over 2,000 mg/l, and a chloride
concentration of nearly 700 mg/l. This well located only
a mile from Agua Hedionda Lagoon may have been affected
by salt water intrusion, or by the migration of connate
waters toward the surface from marine sediments during
times of pumping overdraft.
Historical data from wells adjacent to and upstream
from the immediate study area are also shown in Table 4-1.
The wells are designated for this report as OW-2 (12S/4W-3R),
OW-3 (12S/4W-lOD), W-2 (12S/4W-lOE), OW-4 (12S/4W-10G I.),
OW-5 (12S/4W-10 G 2), OW-6 (12S/4W-lOG 3), OW-7 (12S/4W-l0H 2),
TABLE 4-1 ~g= Hedionda Hydrologic Suberaa (4.31) Historical Well Sqling Data
CHMICAL CONSTITUENTS (mg/l)
WeLL DATE NO. SAMPLED Ca Na so4 c1 B TDS NO3 EC'
ow- 1
ow- 2
ow- 3
W- 2
ow- 4
ow- 5
ow-6
ow- 7
ow-8
w- 3
09-07-60
07-28-61
06-17-64
05-20-64
06-17-64
06-10-64
07-14-59
07-28-61
10-08-59
04-07-60
08-15-60
09-07-60
07-28-61
10-16-53
10-08-59
07-14-59
08-15-60
07-25-62
10-29-63
11-19-64
11-30-54
07-14-59
09-07-60
07-28-61
04-10-62
10-29-63
184 388
142 390
55 240
196 390
107 200
112 179
108 I99
123 I90
124 196
112 206
121 210
138 230
128 204
92 195
128 206
87 115
177 290
174 282
130 435
108 212
103 202
128 212
110 217
92 225
270 683 - 686
249 680
125 487
248 684
66 428
105 404
117 429
131 415
121 439
126 462
133 428 - 433
130 450
101 460
100 404
118 439
312 99
131 664
74 718
120 480
105 438
107 411
107 489
112 411
113 433
0.54 2.268
- -
0.58 1,910
0.43 1,080
0.60 1.726
0.28 1,160
0.29 1.244
0.16 1,137 - 1,290
0.08 1.361
1.073
0.56 ,1,240 - -
0.28 1,291
1,215
0.21 1.248
1,077
0.13 748
0.30 1,760
0.34 1.732
0.34 1.275
0.21 ,1.236
0.46 1,042
0.12 1.342
0.39 1,158
0.45 1.122
0
-
2.5
0
62
4.9
0
13
0.2
0
0.2
1.5 -
1.5
0
3.0
0.2
1.0
0
0
1.0
4.5
0
9.3
0
0
3.215
3,050
3,058
1.630
2.950
1.808
1,918
1,990 -
2,118
1,968
1,990
2.145
1,820
1,100
2,430
2.520
2,128
1.050
1.809
2.105
2,070
1.825
OW-8 (12S/4W-l0H 3), and W-3 (12S/4W-lOJ l), and their loca-
tions are shown in Figure 4-1. Wells W-2 and W-3 are still
being used today.
Based on the historical well sampling data shown
in Table 4-1, the TDS concentration of the groundwater
basin upstream and adjacent to the irmnediate study area
averaged approximately 1,200 mg/l. Chloride concentrations
averaged approximately 500 mg/l in the early 1960's. Data
from wells OW-3 and OW-8 exceeded a TDS concentration of
1,700 mg/l and a chloride concentration of 650 mg/l. Table 8
of DWR's Bulletin No. 106-2, published in June 1967, rates
waters with chloride concentrations greater than 350 mg/l
as "inferior" for irrigation uses, and waters with TDS
concentrations greater than 1,500 mg/l as "inferior" for
domes tic use.
The Basin Plan states the following regarding
groundwater quality in the coastal-plains section of the
Carlsbad Hydrographic Unit:
plains section of this Unit is generally
"Groundwater that occurs in the coastal
sodium chloride in character and has a concentration of TDS that ranges from 500 to 5,000 mg/l. Chemical character
brackish waters that occur in the lagoons; of this water is probably the result of
however, it may be the result of sea water
vim filled valley areas because of over- or connate water migrating into the allu-
extractions at the groundwater reservoir. These waters were probably relatively poor historically, although very few analyses are available prior to 1958."
DWR Bulletin 106-2 shows the range of TDS concen-
trations for groundwater in the immediate study area along
Agua Hedionda Creek as 1,501-2,000 mg/l, with sodium and
chloride representing the major cations and anions, respec-
ively .
B. Present Groundwater Quality
Only one well is presently being used within the
immediate study area, DWR No. 12S/4W-9H, designated Well W-1
for this study, and shown in Figure 4-1. Well W-1 belongs
to Mr. W. Allen Kelly and is located adjacent to Agua Hedionda
Creek approximately 75 yards downstream from the El Camino
Real bridge. Well W-1 has recently been sampled for mineral
analysis by the San Diego Regional Water Quality Control Board
(Regional Board) staff in April, 1977, and by this study team
in April, 1980. Recent data from Well W-1 is shown in Table
4-2. The well is about 100' deep and is thought to draw
water from fractured granitic rock underlying the upper sedi-
mentary deposits (see section C.2. of this chapter for further
details).
One may conclude from this Table that the ground-
water quality is poor adjacent to Agua Hedionda Creek, east
of El Camino Real. TDS values over 1,700 mg/l and chloride
concentrations well above 400 mg/l are shown.
Upstream from El Camino Real and beyond the eastern
boundary of the irmnediate study area, additional wells have
been sampled and analyzed for mineral constituents in recent
years. Their locations are shown in Figure 4-1, and the re-
sulting data is shown in Table 4-2. Well W-2 was sampled by
this study team in April, 1980. This well is located within
the Rancho Carlsbad mobile home park and furnishes irrigation
water for the park and adjacent golf course. This well has a
high yield (300 GPM) and is relatively deep (about 200'). Well
W-3, located approximately one mile upstream from the El Camino
Real bridge, has been sampled recently by the Regional Board
staff in April 1977, and March 1970; and by this study team in
April 1980. Nearby Well No. 12S/4W-llM 1 (W-4) was sampled by
the Regional Board in 1977, and 1979 ; and by this study team in
April 1980. Wells W-3 and W-4 are shallow wells, less than 60
feet deep, and show TDS and chloride concentrations well above
1,200 mg/l and 400 mg/l, respectively. A TDS concentration
greater than 1,700 mg/l was reported for Well W-4.
CHEMICAL CONSTITUENTS (mgll)
mu NO. DATE SAMPLED Cs Na SO' c1 B TDS NO3 EC'
W- 1 04-02-77
12-14-77
04-22-80
W- 2 04-22-80
w- 3 04-21-77
03-09-79
04-22-80
W-4 04-21-77
03-09-79
04-22-80
W- 5 05-06-80
W-6 05-08-80
174 303 - 237 - 300 - 265
162 225
136 231 - 230
172 246
212 282 - 325 - 1,000 - 1.325
257 529
174 444
182 496
197 427
106 425
88 421
127 458
149 482
148 583
255 653
2,637 1,371
1.718 2,371
0.70
0.55
0.52
0.39
0.63
0.30
0.42
0.73
0.36
0.43
2.6
1.4
1.738 0.18
1,290, 0.19
1,428 0.89
1,328 32.0
1,274 0.49
1,228 0.22
1.314 2.9
1.524 12.0
1.758 3.0
2,180 84.0
6,056 6.6
6,596 1.1
2,800 -
2,460
2.350
2.170
2,040
2,300
2,280
2,660
3,300
9,500
LO, 500
During the geohydrologic investigation of the Agua
Hedionda study area in April 1980, the investigating team
drilled two test borings to a depth of 30 feet, between
the high water mark of Agua Hedionda Lagoon and the El
Camino bridge. These test borings have been designated
Wells W-5 and W-6 (Figure 4-l), respectively, progressing
upstream. Groundwater samples were collected from Wells
W-5 and W-6 in May 1980, and the sampling results are
shown in Table 4-2.
These samples, taken much nearer the lagoon than
any existing wells, have extremely high mineral concen-
trations, and may be directly influenced by salt water
intrusion. TDS concentrations exceed 6,000 mg/l and sodium
chloride concentrations are very high.
The Basin Plan states the following regarding the
groundwater quality in the Carlsbad Hydrographic Unit:
"Ratings of groundwater for domestic use in the coastal-plains section range from suitable to inferior. The marginal and inferior ratings are due to a high TDS content along with high nitrate or high sulfate in local areas."
"Ratings of groundwater for irrigation use in this unit are generally marginal to inferior because of the high electrical conductivity and high chloride. "
C. Future Ground Water Quality
1. Introduction
The present groundwater quality of the basin was
described in the previous section. A geohydrologic study of
the basin is contained in the report prepared by Allied
Geotechnical Engineers, Inc. This section utilizes the
data to project future water quality of the basin, consid-
ering the impacts of changing land use patterns, the
proposed water reclamation program, and the aquifer char-
acteristics.
2. Summary of Geohydrologic Conditions -
Agua Hedionda Basin
In what can loosely be called the flood plain
of Agua Hedionda Creek, lies an unconsolidated layer of
silty-clay alluvium. This layer is approximately 20 feet
thick. The alluvium is underlain, and surrounded by inter-
bedded sandstones and silty sandstones of the Santiago For-
mation, which vary in thickness from 0 to 100 feet. The
Lusardi Formation, a boulder conglomerate with interbedded
coarse-grained sandstones, lies between the Santiago For-
mation and the metamorphic basement complex. Figure 4-2
shows a graphic representation of the basin's geology.
The alluvial strata consists of rather impervious
material. Groundwater was encountered near the ground sur-
face in this formation. However, the physical characteristics
of this soil, and the well testing indicates this material is
relatively impervious.
The field borings indicated the lower portions of
the Santiago Formation, the Lusardi Formation and the Base-
ment Complex, are well saturated with water. While the Santi-
ago Formation generally exhibited relatively poor transmis-
sivity, (0.2 ft. 2/day), lenses of coarse, granular and
porous material of much higher porosity (113 ft. 2/day) were encountered.
Judging from the soil characteristics of both the
Lusardi Formation and the Basement Complex in other areas,
these geologic elements are capable of conveying low to
moderate quantities of groundwater.
The total groundwater storage capacity of the
basin is estimated to be 29,000 acre-feet. About 18,400
acre-feet of this storage is thought to contain salt water
(refer to the hydrogeologic investigation for more details).
3. Groundwater Recharge, Movement, and
Safe Yield
The information presented in this section repre-
sents the author's opinion of the groundwater hydrologic
conditions within the basin. Wherever possible, the opinions
are supported by field data, calculations and references.
However, the complexity of mechanisms involved in groundwater
movement require a degree of subjective judgement. As such,
this section should be regarded as learned opinion not in-
disputable fact.
The hydrogeologic investigation of the bash
revealed rather complex geology. Hypothesizing how ground-
water is supplied to and moves through the study area, and
the affect of future land use changes, is equally complex.
Well W-1 within the study area does show the
capacity to produce usable quantities of water. It is be-
lieved this well was drilled into the Basement Complex, ap-
parently drawing water from the fracture zone. The well may
also be receiving water from one or more of the porous lenses
believed to occur within the Lusardi or Santiago Formations.
Another well at the Rancho Carlsbad Mobile Home
Park upstream from the study area is drawing useable quantities
(reportedly up to 500 gpm) of groundwater. Even further up-
stream and well out of the study area the City of Carlsbad
maintains several water supply wells on a standby basis,
which are capable of producing considerable quantities of
water.
Each of these wells exhibit relatively high yields,
particularly for coastal basins. It is likely they are tapping
the more porous strata, which collects groundwater from the
impervious soils, and transport it to the wells. While the
overall basin has a very limited safe yield, the existence
of underlying horizontal pervious material permits the water
to be drawn out by a limited number of high yield wells.
The entire groundwater basin appears to be unconfined
aquifer. No upland sources of aquifer recharge were found,
nor were artesian wells encountered. Observations indicate
the groundwater table roughly parallels the ground contours.
Accordingly, unless one of the upstream wells is pumped very
heavily creating an artifical cone of depression, flow will
move in the same direction as surface water flow. Movement
will occur at a'much slower rate, however.
As with the Buena Vista Basin, the Agua Hedionda
study area appears to be "full", that is, the soils appear
to contain all of the water which is physically possible. In
this state, both infiltrated rainwater and irrigation under-
drainage water percolate downward until reaching either an
impervious horizontal strata or the water table. If an
impervious strata is encountered, the water will migrate in
a slightly dipping horizontal direction along the impervious
strate. It will eventually intersect either the ground sur-
face as seepage or flow into the groundwater reservoir.
Irrigation underdrainage which reaches the
groundwater reservoir will cause a mounding of the water
table there. The mounding effect increases the water
table gradient which in turn causes a lateral migration
of water. Without a mechanism for groundwater mixing,
the inflows of excess irrigation water would not readily
co-mingle with the main portion of the groundwater reservoir.
Rather, the irrigation underdrainage would tend to migrate
down gradient to a surface drainage course.
The lower Agua Hedionda groundwater basin ex-
ibits a vertical water quality gradient. Samples collected
from shallow wells showed TDS.concentrations varying from
6,000 to 6,600 mg/l. Deep wells have TDS concentrations
ranging from 1300 mg/l to 2000 mg/l. The poorer quality
water in the upper strata or the groundwater basin is thought
to be the result of infiltrating irrigation water and the
concentrating effects of phreatophytes.
(24) Luke- Dud&
The study area comprises only about 11% of the
total Aqua Hedionda Basin. As such, the safe yield of the
study area is considerably less than the safe yield of the
entire basin. Being located at the downstream end of the
drainage basin, the study area can be recharged from three
basic mechanisms :
a. Infiltrating rainwater percolating through the Santiago Formation
b. Subsurface flow entering the study area from the upper basin, primarily through
the fractured granitic bedrock
c. Percolating streamflow
d. Infiltration of imported irrigation water
Each of these sources of recharge were examined in the ac-
companying hydrologic investigation which concluded that
the basin’s safe yield is 136 AF/yr. A brief review of the
recharge mechanisms is presented below.
Infiltrating Rainwater Percolating Through the
Santiago Formation
Because annual rainfall rates are far less than
annual potential evapo-transpiration rates, the amount of
rainfall which penetrates the soil mantel is relatively small.
Only during very wet periods is rainfall able to saturate the
soil and percolate into the underlying groundwater table. Based
on such factors as soil moisture holding capacity and potential
evapotranspiration the annual average recharge from infiltrating
rainwater was calculated to be .009 a-ft. /yr./acre. Over
the 2120 acre study area this amounts to 19.1 acre-feet of
recharge per year.
Subsurface Flows Entering the Study Area from
the Upper Basin, Primarily through Fractured
Bedrock
The current state-of-the-art for predicting
subsurface inflow is still quite inexact. No method exists
to measure the horizontal permeability of fractured granite.
Depending upon the length and number of fractures, the bed-
rock permeability can vary considerably. However, using
rather conservative values, it is estimated that the poten-
tial subsurface flow is 136 acre-feetlyr. During those
years when rainfall infiltrates through the Santiago Forma-
tion, the groundwater's hydraulic gradient will not permit
this level of subsurface inflow. In those years, the sub-
surface inflow will be less by an amount equal to the in-
filtrating rainfall.
Percolating Streamflow
Streamflow which percolates into the underlying
groundwater basin is thought to be the main source of re-
charge for that portion of the Agua Hedionda Basin located
east of El Camino Real, particularly the area around Rancho
Carlsbad Golf Course. Wells upstream of the study area are
capable of extracting significant quantities of water. A
recent inventory of groundwater use in this area, conducted
by the staff of the Regional Water Quality Control Board,
showed a water use of approximately 1500 acre-feetlyr. In
excess of 300 acre-feetlyr is being used by the Rancho Carls-
bad Golf Course. Considering the relatively low rate at
which rainfall infiltrates through the Santiago Formation, much
of the recharge is thought to occur from streamflow percolating
into a pervious alluvium.
Within the study area, conditions for streamflow
infiltration are quite different. Borings along the flood-
plain of the lower Agua Hedionda Basin show that in the study
area the stream channel lies mainly on lagoon deposits of
unconsolidated clays. This type of soil deposit is quite
impervious and will not readily permit stream flow infiltration.
For this reason the streamflow infiltration recharge component
in the study area is considered to be negligible. Several
facts supports this conclusion. In the past, several wells
were drilled on the Kelly property west of the present Kelly
well. None of these wells produced significant quantities of
water, indicating poor transmissivity. Also, stream gage
measurements have shown that Agua Hedionda Creek is a gaining
stream in the study area, again indicating a lack of infiltra-
ting s treamf low.
It can be argued that a portion of the infiltra-
ting streamflow which occurs upstream can enter the study area
as subsurface inflows. This mechanism probably accounts for
the relatively high yield of the Kelly well. Logically,
however, streamflow which enters the groundwater basin
upstream of the study area mwt be allocated as part of
the safe yield of the upper basin and not the study area.
Therefore, the infiltrating streamflow component is considered
to be zero.
Infiltration of Imported Irrigation Water
Imported irrigation water, which percolates into
the underlying sediments, also has the potential to contri-
bute to the groundwater basin. Previous studies* in the area
show that approximately .32 acre-feet per year per dwelling
unit is used for landscape irrigation. Agricultural irrigation
rates vary between 2.5 - 3.5 acre-feet per year per acre.
Applied irrigation water will be partially consumed by plant
transpiration and evaporation. However, anywhere from 10%
to 40% will pass the plants' root zone and will percolate
into the underlying sediments. This flow is known as ir-
rigation underdrainage or return waters. The irrigation
process also concentrates dissolved salts. Table 4-3 shows
*City of Carlsbad "Waste Water Reclamation Master Plan Study", 9/79 (Lowry & Associates)
TABLE 4-3 Estimated Irrigation Water Underdrainage to the
Agua Hedionda Groundwater Basin 1980 Conditions
Water Use Water Applied Estimated Underdrainage' (acre-feet) (acre-feet)
Lands cape Irrigation 845
Agricultural Irrigation 1320
169
264
TOTAL 2165 433
1 Based on 80% consumptive use
2 Based on 0.32 acre-feet/year/dwelling unit for 2,600 dwelling units (a0)
3 Based on 3 acre-feet/year/acre over 440 acres
that underdrainage water contributes an estimated 433 acre-
feet per year to the groundwater basin.
Imported irrigation water underdrainage does
contribute significant quantities of water to the groundwater
basin. However, this contribution is man-induced and can-
not be considered as part of the natural groundwater resource.
For this reason irrigation water underdrainage is not consider-
ed as part of the basin's safe yield.
4. Future Groundwater Quality
Chapter 2 projects that most of the study area
would be urbanized by the year 2000. Only about 20% of
the land would remain as open space. At that time an estimated
4,200 dwelling units would be located within the study area.
Using the same assmptions contained in the notes for Table
4-3, it is estimated 1,350 acre-feet will be used for ir-
rigation, of which 270 acre-feet of water will leach into
the underlying sedimentary soils. It is interesting to note,
this is about a 40% reduction of underdrainage water compared
to 1980 conditions.
If some mechanism were available to completely
mix the incoming irrigation underdrainage with the groundwater,
the basin would quickly match the quality of the leaching ir-
rigation water, an estimated 2,200 mg/l. If no groundwater
mixing is assumed, the leaching irrigation water would fol-
low the mounding-horizontal migration mechanism described
earlier. In this case, the existing groundwater quality
would be maintained. The salts contained in the irrigation
underdrainage would continually leach to the surface water-
course and be carried to the ocean.
In reality, the basin is in a "slow-mix'' state,
where leaching irrigation water is slowly co-mingling with
the existing groundwater. Over decades, or possibly centuries,
water in the basin is expected to degrade 2,200 mg/l. This
process may be hastened if groundwater extractions are in-
creased, which would promote the mixing of groundwaters and
underdrainage.
5. Effects of a Reclamation Program
The City of Carlsbad is currently seeking to im-
plement a reclaimed water program in the study area. Re-
claimed water could begin to be distributed for landscape
irrigation within a year. It is estimated that approximately
560 acre-feet of'reclaimed water could be distributed in the
area by the year 2000.
Reclaimed water would be used as a substitute
for a portion of the total irrigation water required (an
estimated 1350 acre-feet) at ultimate development. Using
560 acre-feet per year of reclaimed water with a TDS of
1000 mg/l would increase the overall salt loading of the
basin by 35% compared to irrigating with imported water.
Using the assumptions listed in Table 4-4, and
considering irrigation with both potable and reclaimed water
sources, the average quality of the underdrainage is calculated
to be about 2900 mg/l. Therefore, if groundwater mixing does
occur, the water quality of the basin would reach an estimated
2900 mg/l.
D. Surface Water Quality
Few surface water samples are available within
Subarea 4.31 and the immediate study area. The data shown in
Table 4-4 gives some indication of surface water quality
within the immediate study area, including the mineral con-
tent of Agua Hedionda Creek and Lake Calavera.
Sample S-0 (Figure 4-1) was collected from Lake
Calavera in December 1977, for the "Preliminary Design Re-
port for Lake Calavera Hills Waste Water Treatment Plant,"
March 1978. Sample location S-1 is adjacent to the El Camino
Real bridge over Agua Hedionda Creek. A sample was collected
at location S-1 for the Lake Calavera Hills WWTP report in
December 1977, and by this study team in April 1980.
The data in Table 4-4 indicates poor quality water
in Lake Calvera with a TDS concentration greater than 2,600
mgll. Based on the two samples collected from the lower
reaches of Agua Hedionda Creek, the surface water TDS concen-
tration averages approximately 1,200 mg/l during normal flow
conditions.
Agua Hedionda Lagoon has a direct outlet to the
Pacific Ocean, and its water, therefore, has a mineral content
directly affected by the salinity of marine waters.
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- -
CHAPTER 5
DESCRIPTION OF REQUESTED CHANGES
A. Introduction
The Basin Plan lists beneficial uses of groundwater
in the Agua Hedionda Subunit, which includes Subarea 4.31,
as follows :
o Municipal and Domestic Supply,
o Agricultural Supply,
o Industrial Service Supply.
As noted in Chapter 4, a survey of all known wells
in the immediate study area revealed that only one well,
Well W-1 owned by Mr. W. Allen Kelly, presently exists within
the study area. This well is used for agricultural irrigation1
livestock watering only. One other historic well located near
Well W-1 was abandoned since the early 1960's according to
DWR records. No other wells are used for domestic, agricultural
or industrial purposes at this time. It does not appear that
any new wells will be drilled within the study area in the
future other than for replacement of the existing Well W-1.
The following has been determined about the study
area:
o Groundwater quality is relatively poor,
o Good quality imported water is available for water users,
o Local water purveyors have no plans to develop the lower basin's groundwater supplies.
It has also been stated that, although no present
domestic and industrial uses of groundwater occur, future
use of groundwater for industrial purposes or for irrigation
of salt-tolerant crops may be possible. Future domestic use
(33) Luke- Dud&
TABLE 5-1 Groundwater Quality Objectives for the Aigua
Hedionda Hydrographic Subunit
Parameter (mg/l or as noted) Objective*
Total dissolved solids
Chloride
Percent sodium (%)
Sulfate
Nitrate
Iron
Manganese
Methylene blue active substances
Boron
Odor
Turbidity (JTU)
Color (Units)
Fluoride
1200
500
60
500
10
0.3
0.05
0.5
0.5
None
5
15
1.0
* Concentrations not to be exceeded more than 10% of
the time during any one year period
(34)
of the groundwater within the study area appears to be impracti-
cal due to high mineral concentrations.
It is therefore requested that, for the portion of
the Agua Hedionda Hydrographic Subarea that is described as
the study area in Chapter 1, the following revisions be in-
corporated into the Basin Plan:
1. The beneficial use "Municipal and Domestic"
(m) be designated a potential beneficial use.
2. The beneficial use "Industrial Service Supply"
(IND) be designated a potential beneficial use.
With these requested changes, the beneficial uses of ground-
water in the study area would be as follows:
o Municipal and Domestic Supply (potential)
o Agricultural Supply
o Industrial Service Supply (potential)
Present groundwater quality objectives for the Aqua
Hedionda Hydrographic Subunit, which includes the study area,
are listed in Table 5-1. Present quality of groundwater in the
study area does not meet these objectives based on recent
sampling data.
It is requested the groundwater quality objectives
for this basin be changed in the following manner:
1. Total dissolved solids from 1000 to 3500 mg/l,
2. Chloride from 400 to 800 mg/l,
3. Nitrate from 10 to 45 mg/l
4. Boron from 0.5 to 2.0 mg/l
These revisions would allow the use of secondarily treat-
ed reclaimed water within the lower portions of the Agua Hedionda
drainage basin. With these changes the proposed groundwater
quality objectives for the study area would be as listed in
Table 5-2.
(35) LuUe-Dudek
CHAPTER 6
DEMONSTRATION OF CONSISTENCY BETWEEN
THE REQUESTED CHANGES AND THE STATE'S
NONDEGRADATION POLICY
A. Introduction
The State Water Resources Control Board's Resolution
No. 68-16, "Statement of Policy with Respect to Maintaining
High Quality Waters in California'! (known as the State's
Nondegradation Policy) establishes the basic policy for
setting and changing water quality objectives. Any request
for revision of groundwater objectives must demonstrate that
the revision requested is consistent with the Nondegradation
Policy.
This chapter examines the provisions of the Non-
degradation Policy. The effects of making the requested re-
visions are then examined to show the changes are consistent
with the provisions of Resolution No. 68-16.
B. Smmiary of State's Nondegradation Policy
Resolution No. 68-16 states, in part,
"1. Whenever the existing quality of water is better
than the quality established in policies . . . . , such exist-
ing high quality will be maintained until it has been demon-
strated to the state that, (1) any change will be consistent
with maximum benefit to the people of the state, (2) will
not unreasonably affect present and anticipated beneficial
use of such water, and (3) will not result in water quality
less than that prescribed in the policies."
"2. . . . waste discharge requirements bust be
established) to assure that (a) a pollution or nuisance
(37)
will not occur and (b) the highest water quality consistent
with maximum benefit to the people of the State will be main-
tained.
In a letter dated November 29, 1979 to Lake Calavera
Hills, the staff of the Regional Board explains what specifically
must be considered to demonstrate consistency with the State's
Nondegradation Policy. This letter states, ""he demonstration
must include an assessment of the impacts of the requested
modifications on beneficial uses and an assessment of the
benefits of the requested modifications. The assessment of
the benefits of the requested modifications must, as a
minimum, be based on the following: (1) Identification of
affected populations and evaluations of hardship vs benefit
for each group; (2) evaluation of economic benefit vs
detriment; and (3) evaluation of social benefit vs detriment."
C. Implications of The Requested Changes to the Groundwater
Objectives for the Study Area
The following discussion assesses the consistency
of the requested groundwater modifications with the State's
Nondegradation Policy. Chapters 4 and 5 discuss the
projected impact of revising the water quality objectives
on future water quality and future beneficial uses. Briefly,
it was concluded that changing groundwater objectives, which
would in turn permit reclaimed water to be used in the study
area would result in only minimal groundwater degradation.
However, for the purposes of analyzing a "worst case"
alternative, it is assumed the TDS concentration does reach
the objective of 3,500 mg/l
Revising the basin's groundwater objective will
possibly be detrimental to some groups of people and be
beneficial to other groups. The affected populations have
been classified into three basic groups: (1) Existing and
potential groundwater users, (2) potential users of
reclaimed water, and (3) citizens residing within the
boundaries of the Costa Real Municipal water nistrict.
These three population groups represent the range of people
who may be impacted. An evaluation will be made of the
hardship versus benefit for each of these population groups
The analysis will consider both economic and social factors
It should be noted that the economic analysis
presented below uses current imported water prices. Because
of increasing power costs it is expected the price of imported
water will rise considerably faster than the rate of inflation.
If this fact were considered in the analysis, using reclaimed
water would offer an even greater economic advantage. How-
ever, to analyze a "worst case" situation for reclaimed water,
the chances of rapidly rising imported water costs were not
included in the analysis.
D. Population Group 1 - Existing and Potential Groundwater
Users
Only one functioning well is known to exist within
the study area. Water is used for the agricultural irrigation
on the Kelly property.
It is conceivable that in the future others will
seek to utilize the limited groundwater supplies found
within the basin. As stated earlier, the beneficial uses
for relatively poor quality groundwater are limited to agri-
cultural or landscape irrigation of salt-tolerant crops. Using
the water for industrial process water, such as wash water and
dust control is possible, although not likely. Plainly, no
reasonable method exists to determine how much groundwater
will be utilized in the future. Land use projections show
that landscape irrigation could consume relatively large
quantities of groundwater if a suitable distribution system
were installed. However, the hydrogeologic investigation
showed the "safe" perennial yield of the basin from natural
recharge is 136 acre-feet per year.
(39)
1. Evaluation of Economic Benefit versus
Detriment for the Group 1 Population
Lowering the groundwater objectives for the
study basin is not expected to be detrimental to the existing
Kelly well. The well is located on the extreme upstream por-
tion of the basin for which a change in objectives are request-
ed. In this portion the well will be recharged by a upland
sources which are governed by higher quality objectives.
In Chapter 4 an analysis of future water
quality projected that the basin would eventually degrade
to a TDS concentration of about 2200 mg/l. This represents
a slight increase over the basins current water quality,
which varies between 1300 mg/l and 1700 mg/l. Should
the total dissolved solids concentration rise to the
proposed water quality objective of 3500 mg/l, the ground-
water would probably not be suitable for most agricultural
or landscape irrigation. The only beneficial use which
would not be affected by high mineral concentrations of
groundwater is for industrial service supply.
If the basin degrades to the 3500 mg/l level,
and assuming the Kelly well also degrades to this level (both
highly improbable events), would not necessarily preclude the
use of groundwater for irrigation. A paper authored by R.S.
Ayers entitled, "Water Quality for Agriculture"* reports that
tomato crops can be grown with a 50% decrease in crop yield
when irrigated with water with a TDS of 3250 mg/l. The same
study shows that Bermuda grass can be irrigated with 3700
mg/l TDS water with only a 10% growth reduction. While other
factors such as irrigation rate and soil type must be con-
sidered, it appears the basin would not totally loose the
irrigation water beneficial use by lowering the water quality
objectives. For the purpose of this analysis, however, it is
assumed an alternative water supply would have to be used on
the Kelly property.
* Ayers, R.S. (University of California, Davis) and Westcot, "Water Quality for Agriculture", Food and Agriculture Organization of the United Nations, Rome, 1976.
(40)
Luke- Dud&
While the safe perennial yield of the basin
from natural recharge is estimated to be 136 acre-feet per
year, the Kelly well withdraws an estimated 50 acre-feetlyear
(at a cost of about $500/year). Should it be necessary to
replace the 50 acre-feet of groundwater, presumably reclaimed
water could be used (at a cost of about $6500/year). The
Kelly well consumes less than the basin's natural recharge.
The remaining 86 acre-feetlyr could potentially be used
for irrigation either on the Kelly property or by other
groundwater users. Lowering groundwater objectives could
be detrimental to these potential groundwater users. To
be conservative, it is assumed the 86 acre-feet of water
is lost as a water resource. The total economic benefit
versus detriment to the Group 1 population is listed in
Table 6-1.
TABLE 6-1 Economic Benefit versus Detriment for Group 1
Population Caused by Easing Groundwater Objectives
Group 1 Population Benefit Detriment
Existing Groundwater Users $0 $6000
Potential Groundwater Users $0 $10,300
2. Evaluation of Social Benefit versus Detriment
For the Group 1 Population
Relaxing the groundwater water quality objec-
tives in the study area could remove the basin as a future
source of irrigation water. The social implications of
this loss is small. The basin's storage and annual safe
yield capabilities are very limited. Most property owners
who could use the groundwater for irrigation purposes will
have access to reclaimed water for the same purpose. In
fact, the reclaimed water quality is better quality than
the existing groundwater. The domestic water supply system
is also fairly well developed in the area. As such, no
property owner will be deprived of the use of his land be-
cause of a lack of a suitable water supply. Overall, re-
vising the groundwater objectives is expected to have
minimal social impact on either existing or potential ground-
water users.
E. Population Group 2 - Potential Users of Reclaimed
Water
Changing groundwater objectives is expected to
encourage the use of reclaimed water within the lower
Agua Hedionda basin. The City of Carlsbad is actively
planning to distribute reclaimed water to the area.
It is difficult to accurately predict which
markets will be served. The exact quantity of reclaimed
water to be used depends upon a variety of factors, in-
cluding the availability and cost of potable water, the
proximity of reclaimed water distribution lines, and the
aggressiveness with which reclaimed water is marketed.
However, it is reasonable to expect at least the markets
outlined in Table 6-2 will be served within the basin.
TABLE 6-2 Potential Users of Reclaimed Water
Market
Estimated Irrigable Estimated Average
Land (acres) Use (acre-ftfyr)
1. Landscape
irrigation within
Development
Lake Calavera Hills
150
2. Miscellaneous
adjacent to distribution
landscape irrigation
pipe 25
TOTAL 175'
480
80
560
NOTE: Irrigation water is estimated at 3.2 acre-feetfyear
(43)
1. Economic Benefits versus Detriment For The
Group 2 Population
Changing groundwater objectives in the study
area is expected to enable a variety of landscape areas
to be irrigated with reclaimed water. As shown in Table
6-2, approximately 560 acre-feetlyear of reclaimed water
could reasonably be used within the basin. With an aggressive
marketing program, it is expected additional water could
be utilized. Assuming reclaimed water is sold at $130/acre-
foot (equivalent to 75% of domestic water supply cost), the
total water revenue for irrigation use would be $72,8001
year. If reclaimed water were not available, the cost for
irrigation water from the Costa Real Water District would
be $97,10O/year. The irrigators would realize a net savings ,
of $24,30O/year.
2. Social Benefits versus Detriment For The
Group 2 Population
Providing reclaimed water for irrigation
purposes within the lower Agua Hedionda basin would have
a variety of social benefits for the Group 2 population.
Perhaps the most significant benefit is the availability
of a new water source. Prospects of a severe water
shortage occurring in Southern California are continually
growing. Should a water shortage occur in the near future,
it could have serious consequences for businesses requiring
irrigation water. During a drought, stringent restrictions
are generally placed upon using water for irrigation. Similar
restrictions would not be placed on using reclaimed water. By
using reclaimed water, water-intensive irrigation activities
such as golf courses would be able to avoid both the loss
of business and damage to fairways and greens. Hydrogeologic
studies indicate the existing groundwater basin would be
incapable of providing a significant contribution of irrigation
water. Therefore, revising groundwater objectives to permit
(44)
reclaimed water to be utilized in the basin would be a
significant benefit to the Group 2 population. A possible
social detriment may be associated with developing a
reclaimed water distribution system within the basin. Using
treated wastewater increases the risk of water users being
exposed to a water-borne pathogenic organism. While both
treatment and operation regulations established by public
agencies stringently protect against such problems, health
risks can not be totally eliminated.
Another problem inherent with a reclaimed water
system is the possibility of equipment failure. A broken
distribution main could result in reclaimed water temporarily
flowing to Agua Hedionda Lagoon. A malfunctioning chlorinator
could result in the distribution of inadequately disinfected
water.
Currently, regulatory agencies require back-up
equipment for critical treatment and distribution functions
The stringent regulations essentially eliminate the oppor-
tunities for major public health problems.
F. Population Group 3- Residents Within the Costa Real
Water District
The reclamation projects proposed for the study
area would provide a supplemental or alternate supply of
water to a portion of the Costa Real Water District. If
reclaimed water is provided for landscape irrigation, the
district may delay or avoid the construction of some capital
facilities necessary to expand the potable water system.
In addition, using secondarily treated wastewater for irriga-
tion water saves energy which would be needed to import
alternative potable water supplies.
The 1979 population of the Costa Real Water District
was 31,000* people with a water consumption of 11,135 acre-
feetfyear (.36 acre-feetlyearfperson).
*County Water Authority Estimate
(45)
1. Economic Benefit versus Detriment for Group 3
Population
Implementing a water reclamation program in
the study area would provide 560 acre-feetlyear of water
as a supplemental or alternative water supply to portions
of the Costa Real Water District. It is diddicult to
estimate the true economic worth of an additional water
supply to the residents of the area. Initially, it
appears public agencies will not be able to initially
distribute reclaimed water for a profit. Initial projec-
tions for the Carlsbad area project the expense of operating
the system will about equal the revenues produced from
reclaimed water sales.
The economic benefits could increase markedly
in the future. When contracts to supply imported water
through the California Aqueduct are renegotiated in 1983,
the price of imported water is expected to rise substantially.*
As the price of imported water rises, the sales price of
reclaimed water can also be raised proportionately. This
should result in a net income for the public agencies
distributing reclaimed water, which would benefit the
residents of the area.
2. Social Benefits versus Detriment for the Group 3
Population
Revising groundwater objectives and constructing a
water reclamation system would have significant social
benefits for residents of the Carlsbad area. Supplying an
additional 560 acre-feetlyear of reclaimed water as a
supplemental or alternative water source for irrigation
reduces the dependence on imported water supplies. The
reclaimed water program would supply an amount equivalent
to water used by about 1,860 people. Producing this
supply locally would not only lessen the overall demand on
imported water supplies, but also would reduce the amount
of energy necessary to deliver the water. Table 6-4 shows
* Metropolitan Water District, "1979 Water Pricing Study. " 81 79
LCke.0"
G. Administrative Considerations
On April 3, 1980 the State Water Resources Control
Board adopted Order No. WQ 80-7. The order deals with the
use of reclaimed water in the Agua Hedionda drainage basin.
The State Board action was prompted by an appeal filed by
the County of San Diego in behalf of the Shadow Ridge De-
velopment (known as the Buena Project). The purpose of
the appeal was to test the validity of the so called "one
third" rule imposed as a matter of policy by the San Diego
Regional Board in regard to irrigation with reclaimed water.
As mentioned in a previous section of this study, the Regional
Board generally requires reclaimed water mineral concentrations
to be reduced to one third of the groundwater objective to
allow for evapo-transpiration.
Order No. WQ 80-7 states in part:
"If the Buena Project proponents had reached
or other large groundwater users to irrigate contractual agreement with Rancho Carlsbad
with Buena reclaimed water, instead of ground- water, the 550 mg/l limit could have been appropriately modified for these sites. We urge the County and project proponents to
water users in the area are unwilling to seek such innovative trade-offs. If ground-
accept reclaimed water as a substitute for continued use of groundwater, we could be placed in a position of addressing the is-
be a waste or unreasonable use of water sue of whether such groundwater use would
within the meaning of Section 2 of Article X of the California Constitution.1
Water Code Sections 13550-1 prohibit, under certain circumstances, the use of potable water for irrigation of greenbelt areas when reclaimed water is available for such use."
(47)
TABLE 6-4 Energy Saving of Reclaimed Water Program*
Energy Source Energy Requirement (kwhiacre-feet)
Energy required for imported water
(50/50 blend) 2,700
Energy required for secondary
treatment 400
Energy required for chlorination
(including production) 100
Energy required for distribution pumping (300 ft. head) 400
900 Total energy required for reclaimed water system
water Net energy savings by using reclaimed 1,800
Total annual energy savings in Agua Hedionda
Basin ( 560 acre-feetiyear) 1,000,000 kwhiyear
*Data extracted from Roberts and Hagan, "Energy Requirements of Alternatives in Water Supply, Use and Conservation", December 1975.
This statement seems to suggest that the use of non-
demineralized water at the Rancho Carlsbad Golf Course
(upstream of the study area) was appropriate (or manda-
tory) and presumably in accordance with the State's Non-
degradation Policy. Presumably, the same argument could
be used for the lands irrigated by the Kelly well.
The implication of Order No. WQ 80-7 is that even
with current water quality objectives, non-demineralized
reclaimed water could (or must) be used over a major
portion of the lower Agua Hedionda Basin. No rigorous
analysis was presented to show rigid conformance with
all provisions of the Non-Degradation Policy. The Order
appears to place a high value on wastewater reclamation
projects in the basin.
H. Summary
The material in this chapter seeks to present an
objective analysis of the implications of changing ground-
water objectives in the study area. The preponderance
of evidence indicates that an objective change can be
made without threatening any groundwater resource. No
adverse effects are anticipated on the one functioning
well (Kelly Well) within the study area. Should this
well be impacted by an objective change, water quality
changes would occur very slowly. If and when these
water quality changes do occur, a superior quality
water source (reclaimed water) would be available as
a substitute for groundwater supplies. In the mean-
time, both irrigators and the citizens of the area will
realize substantial economic and social benefits. As
such, it appears that the proposed groundwater ob-
jective changes requested are in conformance with the
State's Non-Degradation Policy.
(49)
TABLE 5-2 Proposed Groundwater Quality Objectives for
the Study Area (Lower Agua Hedionda Hydrographic
Subarea)
Parameter
(mg/l or as noted)
Objective*
Total dissolved solids
Chloride
Percent sodium (%)
Sulfate
Nitrate
Iron
Manganese
Methylene blue active substances
Boron
Odor
Turbidity (JTU)
Color (Units)
Fluoride
3500
800
60
500
45
0.3
0.05
0.5
2.0
None
5
15
1.0
* Concentrations not to be exceeded more than 10% of
the time during any one year period