2010-2011 Report on Groundwater Recharge in the Orange County Groundwater Basin

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2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

Orange County Water District

July 2012

Prepared by: Adam S. Hutchinson, P.G., C.H.G. Recharge Planning Manager

Cover Photo Location: Close up of heron on the Santa Ana River Cover Photo Credit: Angela A. Stanton Stanton Photo Studios [email protected] http://www.stantonphotostudios.com http://angela-stanton.artistwebsites.com

Table of Contents Page Executive Summary 1 Section 1. Introduction 3 2. Background 3 3. Recharge Water Sources 6 3.1 Precipitation 6 3.2 Santa Ana River 8 3.3 Santiago Creek 12 3.4 Imported Water 13 3.5 Recycled Water 14 3.6 Water Losses 15 4. Surface Water Recharge 16 4.1 Operations Overview 16 4.2 Santa Ana River Channel 19 4.3 Weir Ponds 1-4 (Desilting System) 20 4.4 Warner Basin System 21 4.5 Anaheim Lake 22 4.6 Mini-Anaheim Lake 23 4.7 Kraemer Basin 24 4.8 Miller Basin 25 4.9 La Jolla Basin 26 4.10 Placentia Basin 27 4.11 Raymond Basin 28 4.12 Off-River Channel 29 4.13 Olive Basin 30 4.14 Five Coves Basins 31 4.15 Lincoln Basin 32 4.16 Burris Basin 33 4.17 River View Basin 34 4.18 Santiago Basins 35 4.19 Santiago Creek Channel 36 5. Seawater Barrier Recharge 37 5.1 Talbert Gap Seawater Barrier 37 5.2 Alamitos Gap Seawater Barrier 38 6. In-Lieu Recharge 41 7. Recharge Summary 42 7.1 Recharge Sources 42 7.2 Recharge Facilities 46 8. References 48

List of Tables Page ES-1 Recharge Source Summary 2 4-1 Area and Storage Capacity of Surface Water Recharge Facilities 17 4-2 Monthly Recharge in Santa Ana River Channel, 2010-11 19 4-3 Monthly Recharge in Weir Pond 3, 2010-11 20 4-4 Monthly Recharge in Warner Basin System, 2010-11 21 4-5 Monthly Recharge in Anaheim Lake, 2010-11 22 4-6 Monthly Recharge in Mini-Anaheim Lake, 2010-11 23 4-7 Monthly Recharge in Kraemer Basin, 2010-11 24 4-8 Monthly Recharge in Miller Basin, 2010-11 25 4-9 Monthly Recharge in La Jolla Basin, 2010-11 26 4-10 Monthly Recharge in Placentia Basin, 2010-11 27 4-11 Monthly Recharge in Raymond Basin, 2010-11 28 4-12 Monthly Recharge in Off-River Channel, 2010-11 29 4-13 Monthly Recharge in Olive Basin 2010-11 30 4-14 Monthly Recharge in Five Coves Basins, 2010-11 31 4-15 Monthly Recharge in Burris Basin, 2010-11 33 4-16 Monthly Recharge in River View Basin, 2010-11 34 4-17 Monthly Recharge in Santiago Basins, 2010-11 35 4-18 Monthly Recharge in Santiago Creek Channel, 2010-11 36 7-1 Recharge Source Summary 45 7-2 Recharge Facility Summary 47

List of Figures Page ES-1 Total Annual Recharge by Source, 2001-11 2 2-1 OCWD Location Map 4 2-2 Surface Water Recharge Facilities 5 3-1 Annual Rainfall Totals at OCWD Field Headquarters, 1963-2011 6 3-2 Monthly Rainfall Totals at OCWD Field Headquarters, 2010-11 7 3-3 Annual Incidental Recharge, 2001-11 8 3-4 Monthly Local Storm Flow Capture, 2010-11 9 3-5 Annual Base and Storm Flow in the SAR at Prado Dam, 1936-2011 9 3-6 Monthly Santa Ana River Base and Storm Flow Recharged, 2010-11 10 3-7 Prado Dam Storage, 2010-11 11 3-8 Monthly Inflow to Santiago Basins from Santiago Creek, 2010-11 12 3-9 Monthly Recharge of Imported Water, 2010-11 13 3-10 Monthly Recharge of Recycled Water, 2010-11 14 3-11 Monthly Recharge System Losses, 2010-11 15

List of Figures (Cont’d) Page 5-1 Talbert Gap Seawater Barrier 37 5-2 Annual Injection at the Talbert Barrier, 2001-11 38 5-3 Alamitos Gap Seawater Barrier 39 5-4 Annual Injection at the Alamitos Barrier, 2001-11 40 6-1 Annual In-Lieu Recharge, 1978-2011 41 7-1 Total Monthly Recharge by Source, 2010-11 43 7-2 Recharge Sources, 2010-11 44 7-3 Total Annual Recharge by Source, 2001-11 45 7-4 Recharge by Facility, 2010-11 46 7-5 Total Annual Recharge by Facility, 2001-11 47

Appendices Appendix A Acronyms/Definitions Appendix B: Data Tables Description of Data Sources Table B-1 Monthly Rainfall at OCWD Field Headquarters,1963-2011 Table B-2 Annual Incidental Recharge, 2001-11 Table B-3 Monthly Local Inflow Summary, 2010-11 Table B-4 Annual SAR Watermaster Base Flow and Storm Flow, 1936-2011 Table B-5 Monthly SAR Base Flow and Storm Flow Recharged, 2010-11 Table B-6 Monthly Santiago Creek Inflow, 2010-11 Table B-7 Monthly Recharge of Imported and Purchased Water, 2010-11 Table B-8 Monthly Recharge of Recycled Water, 2010-11 Table B-9 Monthly Losses to Ocean and Evaporation, 2010-11 Table B-10 Annual Injection for Talbert Barrier, 1991-2011 Table B-11 Monthly Injection for Talbert Barrier, 2010-11 Table B-12 Annual Injection for Alamitos Barrier, 1991-2011 Table B-13 Monthly Injection for Alamitos Barrier, 2010-11 Table B-14 Annual In-Lieu Recharge of Imported Water, 1978-2011 Table B-15 Monthly In-Lieu Recharge of Imported Water, 2010-11 Table B-16 Annual Recharge by Source, 2001-11 Table B-17 Monthly Recharge Source Summary, 2010-11 Table B-18 Annual Recharge by Facility, 2001-11 Appendix C: Monthly Forebay Percolation Efficiency Reports

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Executive Summary

A total of 19.95 inches of rain was received at the Orange County Water District’s Anaheim Field Headquarters in 2010-11 (OCWD fiscal year ending June 30), which is approximately 37 percent above the historical average of 14.5 inches and is the second consecutive year of above average rainfall.

What made 2010-11 notable was that over half of the rainfall fell in December 2010 with approximately 8 inches falling in a one week period. This extreme event resulted in a record 90,000 acre-feet of water captured behind Prado Dam, most of which, was released to the ocean. The rain received in the Santiago Creek watershed was a 100-year event which caused Irvine Lake to spill and resulted in releases of up to 3,000 cubic feet per second from Villa Park Dam to the Santiago Basins. In December 2010, the Santiago Basins were nearly empty, containing over 11,000 acre-feet of storage space after having been pumped down all summer and fall. The releases from Villa Park Dam filled the Santiago Basins in one week. Combined, storm flow capture from the Santa Ana River and Santiago Creek totaled 80,087 acre-feet, which is well above the recent 10-year average of 57,460 acre- feet.

The above average rainfall also resulted in above-average incidental recharge, which totaled 94,484 acre-feet in 2010-11. This is well above the recent 10-year average of 65,951 acre-feet and supplied 25 percent of the total recharge to the basin in 2010-11.

Over the past three years, the base flows of the Santa Ana River have been relatively constant at approximately 100,000 acre-feet per year with the 2010-11 base flow of 104,469 acre-feet only 1,870 acre-feet more than 2009-10 flows. Nevertheless, compared to the last 10 years, 2010-11 base flow is 20 percent below average.

Imported water recharge was higher in 2010-11 compared to recent years because of deliveries to fill the Metropolitan Water District of Southern California’s storage account (16,500 acre-feet) and the availability of discounted replenishment water, which was made available in May 2010 after a three-year hiatus. Even with these deliveries, imported water deliveries were 40 percent below the 10-year average.

The Groundwater Replenishment System (GWRS) provided 66,084 acre-feet of recycled water to the surface water and seawater barrier recharge systems, which represents a historic high volume of GWRS water recharged to the basin. In total, recycled water from the GWRS and Alamitos Barrier provided 17 percent of water recharged to the basin in 2010-11.

Over the past three years, seawater barrier recharge has been steady ranging from 35,000 to 38,000 acre-feet per year. Protective elevations have been reached in the Talbert Gap, requiring GWRS flows to be shifted from the barrier to the surface water recharge system.

Managed aquifer recharge (MAR), which is the recharge that occurs due to District activities, totaled 290,404 acre-feet in 2010-11, which is four percent above the 10-year average of 278,400 acre-feet per year. Even though storm flow and recycled water recharge were well above average, overall recharge was only slightly above average due to reduced Sana Ana River base flow and reduced imported water recharge. 1 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

Total recharge to the groundwater basin in 2010-11 equaled 384,888 acre-feet, which is 12 percent above the 10-year average of 344,354 acre-feet per year. Total recharge to the basin was above average due to high incidental recharge. Table ES-1 and Figure ES-1 show how 2010-11 recharge compares to the previous 10 years.

Table ES-1 Recharge Source Summary Source FY10-11 10-Year Avg Increase/ % Increase/ (af) (af) (Decrease) (Decrease) (af) SAR Base Flow (1) 104,469 130,754 (26,285) (20) Storm Flow/Local Water (2) 80,087 57,460 22,627 39 Imported/Purchased Water 39,053 65,568 (26,515) (40) Groundwater (3) 0 2,144 (2,144) (100) Recycled Water (4) 66,795 22,477 44,318 197 Total OCWD Recharge (4) 290,404 278,403 12,001 4 Incidental Recharge 94,484 65,951 28,533 35 Grand Total 384,888 344,354 40,534 12 (1) SAR Base Flow based on OCWD data, which may differ slightly from the SAR Watermaster (see Section 3.2). (2) Storm flow includes SAR storm flow and local inflow to the recharge system below Prado Dam. (3) Groundwater was used to augment the injection supply at the Talbert Barrier until July 2006. (4) Recycled water is produced by the GWRS as well as the Leo J. Vander Lans Water Treatment Facility, which is operated by the Long Beach Water Department. Water from the Vander Lans plant is recharged at the Alamitos Barrier. (5) Recharge at all OCWD facilities, also referred to as Managed Aquifer Recharge (MAR).

600,000 Incidental Recharge Groundwater 500,000 Recycled Water Imported/Purchased Water Storm Flow/Local Water 400,000 SAR Base Flow

Avg. 344,350 afy

300,000

200,000 Annual Recharge (af)

100,000

0 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09 2009-10 2010-11 Fiscal Year

Figure ES-1 Total Annual Recharge by Source, 2001-11 2 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

Section 1 Introduction

The Orange County Water District (OCWD or District) was formed by a special act of the California Legislature in 1933 for the purpose of managing and protecting the Orange County groundwater basin. Since its formation, the District has developed a successful managed aquifer recharge (MAR) system that has doubled the yield of the groundwater basin. Aquifer recharge activities conducted by OCWD fall into three categories: 1) Surface Water Recharge, 3) Seawater Barrier Recharge, 3) and In-Lieu Recharge. Naturally occurring recharge to the basin, called incidental recharge, rounds out the sources of recharge to the groundwater basin. For completeness, incidental recharge estimates are presented in this report along with managed aquifer recharge resulting from District activities.

The purpose of this report is to present a breakdown of the water sources used to recharge the basin and which facilities were used to recharge these waters. The focus of this report is OCWD fiscal year 2010-11 (July 1, 2010 - June 30, 2011); however, historical data are provided where appropriate to provide a context for 2010-11 results. Unless otherwise noted, all volumes in this report are for the OCWD fiscal year. Acronyms are presented in Appendix A. Appendix B presents the data used to prepare this report along with a description of the data sources. Appendix C contains 2010-11 Monthly Forebay Percolation Efficiency Reports prepared by Recharge Operations staff, which presents monthly performance data for the surface water recharge facilities operated by the District.

Section 2 Background

The Orange County Groundwater Basin (Basin) underlies the northern half of Orange County and covers approximately 350 square miles (see Figure 2-1). The aquifers comprising the Orange County Groundwater Basin extend over 2,000 feet deep and form a complex series of interconnected sand and gravel deposits (DWR, 1967). In coastal and central portions of the basin, these deposits tend to be separated by extensive lower- permeability clay and silt deposits, known as aquitards (Pressure area). In the inland area of the basin, generally northeast of Interstate 5, the clay and silt deposits become thinner and more discontinuous, allowing groundwater to flow more easily between shallow and deeper aquifers (Forebay).

Shortly after the District was formed in 1933, the District, along with the Orange County Flood Control District (OCFCD), began experimenting with ways to increase the percolation capacity of the Santa Ana River (SAR) channel. These experiments included removing vegetation and re-sculpting the river bank and river bottom (OCWD, 2003a). Based on the success of these experiments, the District began purchasing portions of the SAR channel as they became available. In 1936 the District made its first purchase of 26 acres of the SAR channel for $722. The District eventually acquired six miles of the SAR channel extending from Imperial Highway (SR90) to Ball Road, as shown on Figure 2-2.

3 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

Currently the District owns over 1,500 acres of land in the Forebay on which it has constructed approximately two dozen recharge facilities that cover nearly 1,000 wetted acres (OCWD, 2003a; OCWD, 2003b) (see Figure 2-2). In addition, the District utilizes several flood control basins owned by the OCFCD for recharge. Along with land purchases, the District invested in infrastructure to maximize the ability of the facilities to recharge water, including four rubber dams, over six miles of pipelines, eight pump stations, and a fleet of earthmoving equipment.

Near the coast, seawater intrusion can occur in gaps in the Newport-Inglewood Fault zone. The fault zone is effective in preventing seawater intrusion into the Orange County groundwater basin except in the Alamitos and Talbert Gaps. The gaps are erosional features cut by rivers that deposited permeable sediments, creating pathways for seawater to bypass the fault zone and enter groundwater basin aquifers. To minimize seawater intrusion, the Alamitos Barrier was designed and constructed in 1965 (see Figure 2-1). The Los Angeles County Department of Public Works (LACDPW) operates and maintains Alamitos Barrier facilities under the direction and approval of the Alamitos Barrier Joint Management Committee, whose membership covers five agencies including OCWD. The Talbert Barrier was constructed by OCWD and went on-line in the mid-1970s. The Alamitos

4 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

Barrier currently contains 43 injection wells while the Talbert Barrier contains 36 injection wells. Additional injection wells are continually being added as new information about the extent of seawater intrusion becomes available.

In addition to surface water recharge and seawater injection barriers, the District recharges the basin via in-lieu recharge. In-lieu recharge occurs when groundwater producers take imported water “in-lieu” of pumping groundwater. By turning off wells, the process indirectly recharges the groundwater basin. This program was established by the Metropolitan Water District of Southern California (MWD) in 1977-78 and has been used extensively since then by the District. This type of recharge is effective because it allows for recharge in areas distant from surface water or injection recharge facilities and it frees up capacity in the surface water recharge system for SAR and other sources of water.

5 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

Section 3 Recharge Water Sources

This section presents a summary of the sources of water used to recharge the groundwater basin.

3.1 Precipitation

The Orange County Groundwater Basin is located in a semi-arid region. At OCWD’s Field Headquarters rain gauge in east Anaheim, average annual rainfall for the entire period of record from 1963-2011 is 14.54 inches. In 2010-11, 19.95 inches of rain was recorded, which is approximately 37 percent above the historical average. What made 2010-11 notable was that over half of this rainfall occurred in December 2010 (10.45 inches) with approximately 8 inches falling in a one week period. The remaining months of the year had generally below average rainfall totals. Figure 3-1 shows the annual historical rainfall at this location. Figure 3-2 shows the monthly rainfall received at OCWD Field Headquarters in 2010-11. Table B-1 in Appendix B presents the data used to prepare these graphs.

40

35

30

25 Average (1963-2011): 14.54 inches 20

15 Annual Rainfall (inches) Rainfall Annual 10

5

0 1963-64 1965-66 1967-68 1969-70 1971-72 1973-74 1975-76 1977-78 1979-80 1981-82 1983-84 1985-86 1987-88 1989-90 1991-92 1993-94 1995-96 1997-98 1999-00 2001-02 2003-04 2005-06 2007-08 2009-10 Fiscal Year (July-June)

Figure 3-1 Annual Rainfall Totals at OCWD Field Headquarters, 1963-2011

Rain that falls within the District boundary results in storm flow and incidental recharge. Incidental recharge, which is not directly measured, tends to be widespread over the basin and consists of recharge from hills and mountains adjacent to the groundwater basin,

6 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

12

10.45 Total: 19.95 inches 10

8

6

4 Monthly Rainfall (inches) Rainfall Monthly 2.42 2.35 2.18 2 1.1 0.8 0.57 000 0.03 0.05 0 Jul-10 Oct-10 Apr-11 Jan-11 Jun-11 Feb-11 Mar-11 Dec-10 Sep-10 Nov-10 May-11 Aug-10 Month

Figure 3-2 Monthly Rainfall Totals at OCWD Field Headquarters, 2010-11 underflow beneath the SAR and Santiago Creek, areal recharge from precipitation, irrigation return flows, and urban runoff (OCWD, 2004; OCWD, 2007). Incidental recharge reported herein is net recharge to the basin after losses to Los Angeles County are subtracted from total incidental recharge. The estimated volume of incidental recharge correlates with local rainfall totals. For years with average rainfall, incidental recharge is estimated to be approximately 60,000 acre-feet. For 2010-11 the estimated incidental recharge totaled 94,484 acre-feet. Figure 3-3 shows the annual estimated incidental recharge to the groundwater basin for the last 10 years. Table B-2 in Appendix B presents estimated incidental recharge for 2001 to 2011.

Precipitation that falls within the SAR watershed below Prado Dam and in the Santiago Creek watershed produces locally derived storm flow. Much of this water is captured and recharged; however, storm flow that enters the SAR channel downstream of the District’s recharge facilities is essentially lost to the ocean. During periods of no rainfall, locally derived flows, such as nuisance water, are also captured and recharged. For simplicity, all locally derived flows are categorized as storm flow regardless of the time of year the flows were generated.

7 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

180,000

160,000

140,000

120,000

100,000

80,000

Avg. 65,950 afy 60,000

40,000 Annual Incidental Recharge (af)

20,000

0 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09 2009-10 2010-11 Fiscal Year (July-June)

Figure 3-3 Annual Incidental Recharge, 2001-11

In 2010-11, an estimated 26,096 acre-feet of local storm flow was captured and recharged by the surface water recharge system. This does not include SAR storm flow arriving at Prado Dam (see next section). The bulk of local storm flow captured came in December 2010 when the nearly empty Santiago Basins were filled with water. Figure 3-4 shows the monthly volume of local storm flow captured and recharged in 2010-11. Table B-3 in Appendix B presents the data used to prepare this graph.

3.2 Santa Ana River

The SAR is the largest source of water to the surface water recharge system. In response to development in the upper SAR watershed, SAR base flow increased from the late 1970s to late 1990s (Figure 3-5). In the past 10 years, however, due to conservation and other factors, SAR base flow, which is comprised primarily of treated wastewater, has declined over 30 percent. Urbanization of the watershed has also affected storm flow runoff, with more flow arriving at Prado Dam for a given amount of rain (Warrick and Rubin, 2007). Figure 3-5 shows the total annual Oct.-Sept. water year base flow and storm flow that has flowed past Prado Dam since 1936. Table B-4 in Appendix B presents base flow and storm flow data for the SAR from 1936 to 2011.

8 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

20,000 Direct Rainfall to Recharge Basins Local Storm Flow to Santiago Basins 18,000 Local Storm Flow to SAR Below Imperial Rubber Dam 16,000

14,000

12,000

10,000

8,000

6,000

4,000

Monthly Local Storm Flow Recharged (af) 2,000

0 Jul-10 Apr-11 Oct-10 Jun-11 Jan-11 Feb-11 Mar-11 Nov-10 Dec-10 Aug-10 Sep-10 May-11

*Assumes direct rainfall to 500 acres of recharge basins. Month

Figure 3-4 Monthly Local Storm Flow Capture, 2010-11

700,000

SAR Storm Flow 600,000 SAR Base Flow

500,000

400,000

300,000

200,000

Annual SAR Flow at Prado Dam* (af) 100,000

- 1936 1946 1956 1966 1976 1986 1996 2006 Oct. - Sept. Water Year *Source:SAR Watermaster Reports

Figure 3-5 Annual Base and Storm Flow in the SAR at Prado Dam, 1936-2011

9 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

It is assumed that the surface water recharge system captures and recharges all SAR base flow. However, the volume of SAR storm flow captured and recharged varies and is highly dependent on the distribution of rainfall during the winter months and the operation of the Prado Dam water conservation pool (discussed in the next section).

OCWD data are used to determine the total flow of SAR water reaching the recharge system in order to account for local inflows that occur below Prado Dam. As a result, flows in this report may differ slightly from what is reported by the SAR Watermaster. In addition, there may be differences in monthly volumes of SAR storm flow because the SAR Watermaster accounts for storage behind Prado Dam. SAR Watermaster data, which are based on measurements made by the United States Geological Survey (USGS), are used when OCWD’s gauges and flow meters are not operating and during the storm season to define the base flow component SAR flows. For 2010-11, a total of 104,472 acre-feet of SAR base flow and 53,991 acre-feet of SAR storm flow were captured and recharged. Figure 3-6 shows the monthly variation in recharged SAR base flow and storm flow for 2010-11. Table B-5 in Appendix B presents the data used to prepare this graph.

25,000 SAR Storm Flow SAR Base Flow

20,000

15,000

10,000

Monthly SAR Flow Recharged (af) 5,000

0 Jul-10 Apr-11 Oct-10 Jan-11 Jun-11 Feb-11 Mar-11 Nov-10 Aug-10 Sep-10 Dec-10 May-11 Month

Figure 3-6 Monthly Santa Ana River Base and Storm Flow Recharged, 2010-11

10 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

3.2.1 Prado Dam Water Conservation Pool

Through an agreement with the US Army Corps of Engineers (USACOE), OCWD is allowed to conserve storm flows captured behind Prado Dam. The Prado Dam conservation pool allows for capture and storage of multiple storm events with a maximum of 9,278 acre-feet of storage during the flood season (Oct. 1-Feb. 28) and up to 19,826 acre-feet of storage during the non-flood season (March 1 to Sept. 30) (USACOE, 1994; USFWS, 2000; USACOE, 2002). Generally, releases of water by the USACOE from the conservation pool are coordinated with the District to minimize losses to the ocean.

In 2010-11, an estimated 34,890 acre-feet of storm flow was captured in the conservation pool and subsequently recharged. Extremely heavy rain in December 2010 resulted in a record volume of water retained behind the dam; however, water above the allowable storage level of 9,278 acre-feet (elevation 498 feet above mean sea level) was discharged to the ocean. Additional storm water was captured from testing of Seven Oaks Dam in late February and rains received in March. Figure 3-7 shows how storage behind Prado Dam varied during 2010-11.

100,000

90,000

80,000

70,000

60,000

50,000

40,000

30,000 Prado Dam Storage (af) Max. Conservation Pool Storage (af) 20,000

10,000

0 Jul-10 Apr-11 Oct-10 Jan-11 Jun-11 Feb-11 Mar-11 Nov-10 Dec-10 Aug-10 Sep-10 May-11 Month

Figure 3-7 Prado Dam Storage, 2010-11

11 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

3.3 Santiago Creek

Most of the precipitation that falls in the Santiago Creek watershed results in runoff that is captured behind Santiago and Villa Park Dams. Santiago Dam, which creates Irvine Lake, is owned by the Irvine Ranch and Serrano Water Districts. Villa Park Dam is primarily a flood control dam that is owned and operated by the OCFCD. Precipitation that falls within the approximately 5.5 square mile catchment area that drains the area below Villa Park Dam ends up flowing down Santiago Creek to the District’s Santiago Basins. Occasionally stored water is released from Villa Park Dam to Santiago Basins during or after storm events and during the fall to allow the OCFCD to conduct maintenance on the dam.

In 2010-11, an estimated 23,430 acre-feet of storm flow to Santiago Basins was received from Santiago Creek. Most of the water was received in December 2010 when the nearly empty Santiago Basins were filled within a one week period. Releases from Villa Park Dam were up to 3,000 cubic feet per second during this period. Approximately 988 acre-feet was lost to the ocean after the basins were filled and spilling, providing a net volume of 22,442 acre-feet of recharge water supplied by Santiago Creek. Figure 3-8 shows the monthly inflow from Santiago Creek in 2010-11. Table B-6 in Appendix B presents the data used to prepare this graph.

18,000 Water Released from Villa Park Dam 16,000 Santiago Creek Storm Flow (below Villa Park Dam)

14,000

12,000 Note: 988 acre-feet of December 2010 flow lost to ocean. 10,000

8,000

6,000

4,000 Monthly Santiago CreekInflow (af) Monthly

2,000

0 Jul-10 Apr-11 Oct-10 Jan-11 Jun-11 Feb-11 Mar-11 Nov-10 Aug-10 Sep-10 Dec-10 May-11 Month

Figure 3-8 Monthly Inflow to Santiago Basins from Santiago Creek, 2010-11

12 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

3.4 Imported Water

Imported water, which is purchased from MWD, comes from the either the Colorado River Aqueduct (CRA) or the State Water Project (SWP). Raw, untreated MWD water can be delivered to the surface water recharge system in multiple locations, including Anaheim Lake (OC-28/28A), Santa Ana River (OC-11), Irvine Lake (OC-13), and San Antonio Creek near the City of Upland (OC-59). Connections OC-28, OC-11 and OC-13 supply OCWD with CRA water. Connection OC-59 supplies OCWD with SWP water and OC-28A supplies OCWD with a variable blend of CRA and SWP water. Treated MWD water is purchased for recharge from various other MWD connections for use at the seawater barriers and for in- lieu recharge.

In 2010-11, 16,500 acre-feet of imported water was recharged into MWD’s storage account (Conjunctive Use Program-CUP). Another 21,474 acre-feet of imported water was recharged following MWD’s decision to make 225,000 acre-feet of discounted replenishment water available to all water agencies in their service area on a first-come-first- serve basis. A total 1,079 acre-feet of treated MWD water was purchased for recharge at the Talbert and Alamitos Barriers. Figure 3-9 shows the monthly totals of imported water recharged in 2010-11. Table B-7 in Appendix B presents the data used to prepare this graph.

20,000 Barrier Recharge 18,000 Surface Water Recharge

16,000 In-Lieu Recharge

14,000

12,000

10,000

8,000

6,000 Total Monthly Recharge (af) Recharge Monthly Total 4,000

2,000

0 Jul-10 Apr-11 Oct-10 Jan-11 Jun-11 Feb-11 Mar-11 Nov-10 Aug-10 Sep-10 Dec-10 May-11 Month

Figure 3-9 Monthly Recharge of Imported Water, 2010-11

13 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

3.5 Recycled Water

In January 2008, the District’s Groundwater Replenishment System (GWRS) became operational. The GWRS replaced Water Factory 21 and includes advanced water treatment processes consisting of micro-filtration (MF) followed by reverse osmosis (RO) and ultraviolet (UV) light disinfection in combination with hydrogen peroxide. The plant is designed to treat wastewater and produce up to 72,000 acre-feet per year of highly treated recycled water. The recycled water is delivered to the Talbert Barrier and the surface water recharge system, specifically, Kraemer and Miller Basins. To supply water to Kraemer and Miller Basins, a 13-mile pipeline was constructed adjacent to the Santa Ana River from the treatment plant in Fountain Valley to Kraemer and Miller Basins in Anaheim (see Figure 2- 2). In 2010-11, 33,634 acre-feet of recycled water was recharged in the Talbert Barrier and 32,450 acre-feet was recharged in Kraemer/Miller Basins.

In 2010-11, a total of 2,144 acre-feet of recycled water was recharged at the Alamitos Barrier with 712 acre-feet counted as recharge to the Orange County groundwater basin. Recycled water supplied to the Alamitos Barrier is produced by the Leo J. Vander Lans Water Treatment Facility, which is operated by the Long Beach Water Department under contract with the Water Replenishment District of Southern California (WRD). Figure 3-10 shows the monthly totals of recycled water recharged in 2010-11. Table B-8 in Appendix B presents the data used to prepare this graph.

9,000

Alamitos Barrier 8,000 Talbert Barrier 7,000 Surface Water Recharge System

6,000

5,000

4,000

3,000 Monthly Recharge (af) Recharge Monthly

2,000

1,000

0 Jul-10 Apr-11 Oct-10 Jun-11 Jan-11 Feb-11 Mar-11 Nov-10 Aug-10 Sep-10 Dec-10 May-11 Month

Figure 3-10 Monthly Recharge of Recycled Water, 2010-11 14 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

3.6 Water Losses

Water losses from the surface water recharge system include water in the SAR, Santiago Creek and Carbon Creek that flow past the recharge system. The majority of water lost to the recharge system occurs in the SAR channel when flows are in excess of 1,000 cubic feet per second (cfs) because the rubber dams used to divert water from the channel are typically deflated during periods of high flow. In 2010-11, 168,650 acre-feet of SAR water was lost to the ocean, with most of the losses occurring in December 2010 and January 2011 (Figure 3-11). An additional 988 acre-feet were lost in Santiago Creek in December 2010 when the Santiago Basins were spilling

Another source of water loss is evaporation. For many of the recharge basins, evaporative losses are included in the storage change. No effort is made to estimate evaporative losses in the recharge basins because evaporative losses are minor compared to the recharge volumes involved. For other facilities, such as the SAR channel, evaporative losses are calculated based on historical average evaporation pan readings taken at Field Headquarters. It is assumed that the water surface area is 500 acres, which is approximately half of the recharge system wetted area. Using this approach, it is estimated that approximately 2,207 acre-feet of water was lost to evaporation in 2010-11 from these facilities. Figure 3-11 shows the estimated monthly losses to the ocean and evaporation losses in 2010-11. Table B-9 in Appendix B presents the data used to prepare this graph.

90,000 Evaporation Losses Losses to Ocean in Carbon Creek 80,000 Losses to Ocean in Santiago Creek Losses to Ocean in SAR 70,000

60,000

50,000

40,000

Monthly Losses (af) Losses Monthly 30,000

20,000

10,000

0 Jul-10 Oct-10 Apr-11 Jun-11 Jan-11 Mar-11 Feb-11 Nov-10 Aug-10 Sep-10 Dec-10 May-11 Month

Figure 3-11 Monthly Recharge System Losses, 2010-11 15 2010-11 Report on Groundwater Recharge in the Orange County Groundwater Basin

Section 4 Surface Water Recharge

This section provides an overview of the surface water recharge system and the volumes and sources of water used for recharge. In addition, the monthly recharge performance of each facility is presented. Recharge performance data are based on monthly Forebay Percolation Efficiency Reports prepared by District Recharge Operations staff. Copies of the Forebay Percolation Efficiency Reports for 2010-11 are presented in Appendix C.

4.1 Operations Overview

The District’s surface water recharge system is currently comprised of 25 facilities which cover over 1,000 wetted acres and have a storage volume of over 26,000 acre-feet (see Figure 2-2 for facility locations). Table 4-1 lists the area and storage capacity of each recharge facility.

The main source of inflow to the recharge system is the SAR. When SAR flows reach the Imperial Rubber Dam located just downstream of Imperial Highway, the flows are divided into two streams of water. The first stream is diverted from the SAR to Weir Ponds 1-4 (Desilting System). The second stream is the remaining flow, which is bypassed around the dam and placed back into the SAR channel. The maximum flow that can be diverted to the Desilting System is 500 cubic feet per second (cfs). Up to 500 cfs can also be bypassed around the dam.

Flows that pass through the Desilting System are split at Weir Pond 4 with up to 400 cfs being conveyed to Foster-Huckleberry, Conrock, Warner, and Little Warner Basins (Warner System). At Little Warner Basin, water is conveyed via the 66-inch diameter Warner Transmission Pipeline to Anaheim Lake. Water reaching Anaheim Lake can also be conveyed via a pipeline around the north side of Anaheim Lake to downstream basins, including Mini-Anaheim Lake, Kraemer Basin, and Miller Basin. This same pipeline can deliver water to Carbon Creek near Miller Basin, which then conveys water to La Jolla Basin, Placentia Basin, and Raymond Basin.

Water conveyed from Weir 4 to the Off-River Channel flows downstream where some flows into Olive Basin. Left over water that does not percolate in the Off-River Channel then flows into Five Coves Basins via tubes under Carbon Canyon Diversion.

Similar to the Imperial Highway Rubber Dam, water reaching the Five Coves Rubber Dam is split into two streams, with one stream diverted to the Five Coves Basins and the other stream bypassed around the dam back into the SAR channel. The Five Coves Rubber Dam has a maximum diversion capacity of 500 cfs and a maximum bypass capacity of 250 cfs. Water bypassed around the dam to the SAR channel must be carefully monitored so water is not lost to the ocean.

Water that enters Five Coves Basins passes to Lincoln Basin and then into Burris Basin. From Burris Basin, water is pumped to Santiago Basins via the Burris Basin Pump Station. The pump station has four incline-turbine pumps, which have a combined pumping capacity of 235 cfs or 105,500 gallons per minute. Pumped water is conveyed to the Santiago Basins via the 60-inch diameter Santiago Pipeline, which is approximately five miles long (see Figure 2-2). 16 Table 4-1 Area and Storage Capacity of Surface Water Recharge Facilities

Max. Max. Facility Max. Water Storage Wetted Invert Surface Capacity Facility Area Elev. Elevation (1) (1) (acres) (ft msl) (ft msl) (af) Anaheim Lake 72 175 224 2,260 Burris Basin 120 110 172 2,670 Conrock Basin (Warner System) 25 193 244 1,070 Five Coves Basin: Lower 16 179 195 182 Five Coves Basin: Upper 15 182 200 164 Foster-Huckleberry Basin (Warner System) 21 210 246 630 Kraemer Basin 31 164 220 1,170 La Jolla Basin 6.5 199 205 26 Lincoln Basin 10 183 190 60 Little Warner Basin (Warner System) 11 205 239 225 Miller Basin (2) 25 200 224 300 Mini-Anaheim Lake 5 230 234 13 Off-River Channel 89 241-205 N/A N/A Olive Basin 5.8 187 228 122 Placentia Basin (2) 9 155 195 350 Raymond Basin (2) 19 145 170 370 River View Basin 3.6 186 190 11 Santa Ana River: Imperial Hwy to Orangewood Ave. 291 270-167 N/A N/A Santiago Basins 187 150 286 13,720 Santiago Creek: Santiago Basins - Hart Park (3) 2.6 285-183 N/A N/A Warner Basin 70 187 239 2,620 Weir Pond 1 6 258 263 28 Weir Pond 2 9 254 259 42 Weir Pond 3 14 247 259 160 Weir Pond 4 4 244 255 22 Totals 1,068 26,215 Notes: (1) Maximum water surface elevation is typically not achieved for most facilities due to need to reserve buffer space for system flow and level fluctuations. Elevations and storage volumes are not applicable (N/A) to stream/river channels. (2) Owned by Orange County Flood Control District (OCFCD). Max., storage capacity shown is max. flood control storage. (3) Various owners, including OCFCD, City of Orange, and MWD.

17 Water in the Santiago Pipeline also supplies River View Basin and Santiago Creek. A pump station in Santiago Basins allows the District to reverse the flow direction in the Santiago Pipeline and pump stored water from the basins to Santiago Creek, River View Basin, Burris Basin, and to the SAR channel. Pumping from the Santiago Basins is typically done during the fall months to maximize storage space for storm water capture.

Due to suspended sediment in SAR water, all of the recharge facilities clog, resulting in reduced recharge rates over time. To mitigate clogging of the SAR channel, the District stirs up the top few inches of sediment using heavy equipment, which forces the accumulated fine-grained sediments to be re-suspended and flow downstream. In the other facilities, cleaning is accomplished by draining the water from the facilities, allowing the accumulated fine-grained sediments to dry, and then removing them from the bottom using heavy equipment. The basin sidewalls, which typically have 3:1 slopes, are disturbed using bulldozers. This action breaks up the clogging layer, but does little to remove it. Eight recharge basins have permanently installed pumps that allow the District to transfer water to other facilities and to rapidly dewater the basins for cleanings. Other facilities are drained by gravity.

Generally, the District will take a basin out of service for cleaning when the recharge rate declines by 65 to 75 percent of the starting, clean recharge rate. Terminal recharge basins, including Anaheim Lake, Kraemer Basin, Miller Basin, La Jolla Basin, and River View Basin, can easily be taken off-line and cleaned without affecting other facilities. However, “flow- through” basins, such as Weir Ponds 1-4, Warner Basin, Five Coves Basins, Lincoln Basin, and Burris Basin, cannot be easily taken off-line without affecting downstream facilities. As a result, “flow-through” basins are not cleaned as often as the terminal basins.

18

4.2 Santa Ana River Channel

Key Facts: Wetted Area: 291 acres Maximum Water Depth: N/A Maximum Storage Capacity: N/A Year Placed Into Service: 1936 Water Sources: SAR, Imported/Purchased Water

The Santa Ana River channel is OCWD’s single largest and oldest recharge facility. It is also one of the most effective recharge facilities due to the self-cleaning nature of the channel. The District owns six miles of the SAR channel extending from Imperial Highway (SR90) to Ball Road, as shown on Figure 2-2.

The river channel is actively managed with heavy equipment to maximize the wetted surface area of the channel and to remove accumulated fine-grained sediments that coat and clog the channel bottom. Maximizing the wetted surface area is typically done by constructing sand levees in the channel to force the water to spread out. The sand levees wash out during storm events and thus do not hinder the storm flow conveyance capacity of the channel.

Table 4-2 summarizes the monthly recharge provided by the Santa Ana River channel in 2010-11.

Table 4-2 Monthly Recharge in Santa Ana River Channel, 2010-11 Month Recharge (af) Notes July 2010 4,820 August 2010 3,662 Only used 1/3 of river September 2010 4,846 October 2010 5,025 November 2010 4,656 December 2010 5,767 January 2011 6,161 Average percolation rate of 99 cfs February 2011 5,780 March 2011 5,722 April 2011 5,758 May 2011 5,766 June 2011 5,620 Total 63,583 5-Year Avg 61,565 Average for FY06-07 to FY10-11

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4.3 Weir Ponds 1 – 4 (Desilting System)

Key Facts: Wetted Area: 33 acres Maximum Water Depth: 12 feet Maximum Storage Capacity: 252 af Year Placed Into Service: 1973 Water Sources: SAR, Imported/Purchased Water

Water diverted from the SAR Channel at Imperial Rubber Dam enters Weir Ponds 1 to 4, which collectively comprise the Desilting System. This system mainly provides sediment removal and little to no recharge. Aside from high solids loading that clogs the system; recharge is further inhibited by shallow groundwater conditions in the area.

Weir Ponds 1 and 2 do not provide any meaningful recharge and thus are not included in the table below. Table 4-3 summarizes the monthly recharge provided by Weir Pond 3 in 2010-11.

Table 4-3 Monthly Recharge in Weir Pond 3, 2010-11 Month Recharge (af) Notes July 2010 60 Estimated August 2010 30 Estimated September 2010 15 Estimated October 2010 30 Estimated November 2010 60 Estimated December 2010 60 Estimated January 2011 60 Estimated February 2011 60 Estimated March 2011 60 Estimated April 2011 60 Estimated May 2011 60 Estimated June 2011 30 Estimated Total 585 5-Year Avg 592 Average for FY06-07 to FY10-11

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4.4 Warner Basin System

Key Facts: Wetted Area: 127 acres Maximum Water Depth: 52 feet Maximum Storage Capacity: 4,545 af Year Placed Into Service: 1974 Water Sources: SAR, Imported/Purchased Water

Warner Basin, named after long-time Orange County Supervisor and OCWD Board member, Willis H. Warner, is a large, deep recharge basin that was put into service in 1974. The Warner Basin System is comprised of Foster-Huckleberry, Conrock, Warner, and Little Warner Basins. Foster-Huckleberry and Conrock Basins are not cleaned or maintained and therefore serve more as desilting basins than as recharge basins.

Warner Basin was last cleaned in summer 2006. Consequently, the annual recharge for 2010-11 is below average. It is difficult to clean Warner Basin due to the large volume of water that must be evacuated and the length of time it takes to dry and clean the basin. Table 4-4 summarizes the monthly recharge provided by the Warner Basin System in 2010- 11.

Table 4-4 Monthly Recharge in Warner Basin System, 2010-11 Month Recharge (af) Notes July 2010 500 August 2010 500 September 2010 551 October 2010 600 November 2010 600 December 2010 609 January 2011 422 February 2011 550 March 2011 931 April 2011 1,264 May 2011 1,331 June 2011 1,211 Total 9,069 5-Year Avg 14,036 Average for FY06-07 to FY10-11

21

4.5 Anaheim Lake

Key Facts: Wetted Area: 72 acres Maximum Water Depth: 49 feet Maximum Storage Capacity: 2,260 af Year Placed Into Service: 1961 Water Sources: SAR, Imported/Purchased Water

Anaheim Lake is the District’s oldest deep recharge basin, having been put into service in 1961. From 1961 to 1975, only imported water from MWD was recharged in the basin. Since the completion of the Warner Transmission Pipeline connecting Warner Basin with Anaheim Lake in 1975, both SAR water and MWD water have been recharged in Anaheim Lake.

Anaheim Lake was drained and cleaned in September 2010 and May/June 2011. The basin was out of service during the entire month of September 2010 to regrade portions of the basin bottom to fill in poor draining areas and to conduct submersible pump repairs.

Large amounts of imported water from MWD were recharged in the basin during the non- storm season.

Table 4-5 summarizes the monthly recharge provided by Anaheim Lake in 2010-11.

Table 4-5 Monthly Recharge in Anaheim Lake, 2010-11 Month Recharge (af) Notes July 2010 1,935 OC-28 and SAR inflow August 2010 897 Begin draining September 2010 0 Out of service for cleaning, maintenance October 2010 1,587 Basin cleaned, OC-28 and SAR inflow November 2010 3,467 OC-28 and SAR inflow December 2010 2,944 SAR inflow January 2011 2,640 SAR inflow February 2011 2,428 SAR inflow March 2011 2,240 SAR inflow April 2011 1,894 SAR inflow May 2011 1,123 Begin draining June 2011 2,855 Basin cleaned, OC-28 and SAR inflow Total 24,010 5-Year Avg 25,687 Average for FY06-07 to FY10-11

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4.6 Mini-Anaheim Lake

Key Facts: Wetted Area: 5 acres Maximum Water Depth: 4 feet Maximum Storage Capacity: 13 af Year Placed Into Service: 1995 Water Sources: SAR, Imported/Purchased Water

Mini-Anaheim Lake is a small, shallow basin that was constructed on land just east of Anaheim Lake. The basin can receive SAR water, purchased water, and imported water from the adjacent OC- 28/28A connection.

Table 4-6 summarizes the monthly recharge provided by Mini-Anaheim Lake in 2010-11.

Table 4-6 Monthly Recharge in Mini-Anaheim Lake, 2010-11 Month Recharge (af) Notes July 2010 583 SAR and OC-28 inflow August 2010 522 OC-28 inflow September 2010 100 OC-28 inflow October 2010 229 SAR and OC-28 inflow November 2010 276 SAR and OC-28 inflow December 2010 220 SAR and pumped from Anaheim Lake January 2011 513 SAR and pumped from Anaheim Lake February 2011 342 SAR and pumped from Anaheim Lake March 2011 340 SAR and pumped from Anaheim Lake April 2011 451 SAR inflow May 2011 469 SAR inflow June 2011 365 SAR and OC-28 inflow Total 4,410 5-Year Avg 3,861 Average for FY06-07 to FY10-11

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4.7 Kraemer Basin

Key Facts: Wetted Area: 31 acres Maximum Water Depth: 56 feet Maximum Storage Capacity: 1,170 af Year Placed Into Service: 1988 Water Sources: SAR, Imported/Purchased, Recycled Water

Kraemer Basin is a 31 acre deep basin that was put into service in 1988. Due to the coarse sands and gravels that underlie the basin and high depth to groundwater (>100 feet), Kraemer Basin is one of the most efficient recharge basins on a per-acre basis operated by OCWD.

Kraemer Basin was taken out of service in late October to early November 2010 and in March 2011 for cleaning. Total annual recharge in 2010-11 was 55 percent above the 5- year average due to the large quantities of imported and GWRS water recharged. In addition, the strategy of pumping water from Anaheim Lake, which reduces the solids loading of SAR water to Kraemer Basin, also increased basin recharge. Table 4-7 summarizes the monthly recharge provided by Kraemer Basin in 2010-11.

Table 4-7 Monthly Recharge in Kraemer Basin, 2010-11 Month Recharge (af) Notes July 2010 122 Used a few days August 2010 2,821 SAR and OC-28 inflow September 2010 4,101 SAR and OC-28 inflow October 2010 2,334 SAR and OC-28 inflow November 2010 2,600 SAR, OC-28 and GWRS inflow December 2010 4,993 GWRS inflow and pumped from Ana. Lake January 2011 3,514 GWRS inflow and pumped from Ana. Lake February 2011 1,702 Pumped from Ana. Lake March 2011 728 Pumped from Ana. Lake April 2011 2,621 SAR inflow May 2011 3,333 SAR and OC-28 inflow June 2011 6,509 SAR, OC-28 and GWRS inflow Total 35,378 5-Year Avg 22,771 Average for FY06-07 to FY10-11

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4.8 Miller Basin

Key Facts: Wetted Area: 25 acres Maximum Water Depth: 24 feet Maximum Storage Capacity: 300 af Year Placed Into Service: 1963 Water Sources: SAR, Imported/Purchased, Recycled Water

Miller Basin is a flood retarding basin owned by the OCFCD that was constructed in 1963. The OCFCD allows OCWD to use the basin for recharge as long as water levels are kept within certain limits (OCWD, 2001; OCWD, 2003c).

Miller Basin was dedicated to the recharge of GWRS water for most of 2010-11. A flood event in December 2010 caused water from the adjacent Carbon Canyon Diversion channel to spill into the basin, which clogged the basin. GWRS water was recharged in Kraemer Basin while Miller Basin was being cleaned. The continued dedication of Miller Basin to GWRS water resulted in above-average recharge in 2010-11.

Table 4-8 summarizes the monthly recharge provided by Miller Basin in 2010-11.

Table 4-8 Monthly Recharge in Miller Basin, 2010-11 Month Recharge (af) Notes July 2010 2,156 GWRS inflow August 2010 2,212 GWRS inflow September 2010 1,946 GWRS inflow October 2010 1,812 GWRS inflow November 2010 1,307 GWRS inflow December 2010 2,222 GWRS and overflow from Carbon Div. January 2011 1,950 GWRS inflow February 2011 2,381 GWRS inflow March 2011 1,755 GWRS inflow April 2011 646 SAR and GWRS inflow May 2011 1,844 OC-28, GWRS and SAR inflow June 2011 1,403 OC-28 and SAR inflow Total 21,634 5-Year Avg 18,925 Average for FY06-07 to FY10-11

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4.9 La Jolla Basin

Key Facts: Wetted Area: 6.5 acres Maximum Water Depth: 5 feet Maximum Storage Capacity: 26 af Year Placed Into Service: 2007 Water Sources: Carbon Creek, SAR, Imported/Purchased Water

La Jolla Basin is the District’s newest recharge basin and was put into service in December 2007. Water is diverted to the basin via a small rubber dam in Carbon Creek. Water in Carbon Creek is typically SAR or imported water discharged to the creek near Miller Basin. Due to the highly permeable sediments underlying the basin, recharge rates on a per- acre-basis, are the highest of any facility operated by OCWD.

Average recharge for the full first three years of operation is 5,666 acre-feet per year. Total recharge in 2010-11 of 7,837 acre-feet is 38 percent above average due to the large quantities of imported water recharged.

Table 4-9 summarizes the monthly recharge provided by La Jolla Basin in 2010-11.

Table 4-9 Monthly Recharge in La Jolla Basin, 2010-11 Month Recharge (af) Notes July 2010 635 SAR and OC-28 inflow August 2010 899 SAR and OC-28 inflow September 2010 424 SAR and OC-28 inflow October 2010 326 SAR and OC-28 inflow November 2010 787 SAR and OC-28 inflow December 2010 510 Pumped water from Anaheim Lake January 2011 590 Pumped water from Anaheim Lake February 2011 762 Pumped water from Anaheim Lake March 2011 409 SAR inflow April 2011 846 SAR and OC-28 inflow May 2011 433 SAR and OC-28 inflow June 2011 1,216 SAR and OC-28 inflow Total 7,837 Avg 5,666 3-Year Average, FY08-09-FY10-11. Placed in service December 2007.

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4.10 Placentia Basin

Key Facts: Wetted Area: 9 acres Maximum Water Depth: 40 feet Maximum Storage Capacity: 350 af Year Placed Into Service: 1962 Water Sources: Carbon Creek, SAR, Imported/Purchased Water

Placentia Basin is a flood retarding basin owned by the OCFCD that was constructed in 1962. The basin is designed to retard flood flows in Carbon Creek; however, the OCFCD allows OCWD to use 20 acre-feet of basin storage for water conservation (OCFCD, 1975). Even though OCWD can use the basin year-round, historically, OCWD has only used the basin during OCFCD’s non-storm season (April 15- October 15).

The District has not used Placentia Basin in recent years because approximately two to four acre-feet per day of treated groundwater is discharged to the basin from a treatment system located on the eastern edge of the basin. Rather than pump this water from the basin in order to clean it, OCWD has been bypassing this basin and using downstream Raymond Basin. OCWD did use Placentia Basin in June 2011 by adding to the water already in the basin.

Table 4-10 summarizes the monthly recharge provided by Placentia Basin in 2010-11.

Table 4-10 Monthly Recharge in Placentia Basin, 2010-11 Month Recharge (af) Notes July 2010 0 Not used August 2010 0 Not used September 2010 0 Not used October 2010 0 Not used November 2010 0 Not used December 2010 0 Not used January 2011 0 Not used February 2011 0 Not used March 2011 0 Not used April 2011 0 Not used May 2011 0 Not used June 2011 354 SAR and OC-28 inflow Total 354 5-Year Avg 945 Average for FY06-07 to FY10-11

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4.11 Raymond Basin

Key Facts: Wetted Area: 19 acres Maximum Water Depth: 25 feet Maximum Storage Capacity: 370 af Year Placed Into Service: 1962 Water Sources: Carbon Creek, SAR, Imported/Purchased Water

Raymond Basin is a flood retarding basin owned by the OCFCD that was constructed in 1962. The basin is designed to retard flood flows in Carbon Creek; however, the OCFCD allows OCWD to recharge water provided that the inflow matches the percolation rate (i.e., no stored water) (OCFCD, 1975).

In 2010-11, Raymond Basin was used for 11 months out of the year. In April/May 2011 the basin was cleaned and the bottom re-graded. The extensive use of the basin and recharging clean, imported water resulted in nearly 50 percent above average recharge in 2010-11.

Table 4-11 summarizes the monthly recharge provided by Raymond Basin in 2010-11.

Table 4-11 Monthly Recharge in Raymond Basin, 2010-11 Month Recharge (af) Notes July 2010 300 OC-28 and SAR inflow August 2010 511 OC-28 and SAR inflow September 2010 564 OC-28 and SAR inflow October 2010 357 OC-28 and SAR inflow November 2010 185 OC-28 and SAR inflow December 2010 18 Pumped water from Ana. Lake January 2011 381 Pumped water from Ana. Lake February 2011 167 Pumped water from Ana. Lake March 2011 45 Pumped water from Ana. Lake April 2011 5 No inflow, recharge of stored water May 2011 237 OC-28 and SAR inflow June 2011 387 OC-28 and SAR inflow Total 3,157 5-Year Avg 2,123 Average for FY06-07 to FY10-11

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4.12 Off-River Channel

Key Facts: Wetted Area: 89 acres Maximum Water Depth: N/A Maximum Storage Capacity: N/A Year Placed Into Service: 1936 Water Sources: SAR, Imported/Purchased Water

The Off-River Channel was part of the main SAR channel prior to completion of the Santa Ana River Water Conservation and Flood Control Project in December 1973. This project included installation of the center levee which created the main SAR channel for flood control and a parallel off-river channel for water conservation.

In addition to providing recharge, the Off-River Channel serves to convey water to Burris Basin and eventually to Santiago Basins. This reduces the need to divert water to Burris Basin at the Five Coves Rubber Dam. Flows that reach the end of the Off-River Channel, flow under Carbon Canyon Diversion into the Upper Five Coves Basin. Periodic stream flow measurements are made in the Off-River Channel prior to entry into the Five Coves Basins to estimate recharge in the Off-River Channel.

Table 4-12 summarizes the monthly recharge provided by the Off-River Channel in 2010-11.

Table 4-12 Monthly Recharge in Off-River Channel, 2010-11 Month Recharge (af) Notes July 2010 59 Estimated August 2010 250 Estimated September 2010 298 Estimated October 2010 307 Estimated November 2010 300 Estimated December 2010 238 Estimated January 2011 365 Estimated February 2011 177 Estimated March 2011 Lumped with Five Coves, estimated 5 310 cfs/day for month April 2011 Lumped with Five Coves, estimated 5 300 cfs/day for month May 2011 690 Estimated 12 cfs for days with flow June 2011 714 Estimated 12 cfs for days with flow Total 4,008 5-Year Avg 4,846 Average for FY06-07 to FY10-11

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4.13 Olive Basin

Key Facts: Wetted Area: 5.8 acres Maximum Water Depth: 41 feet Maximum Storage Capacity: 122 af Year Placed Into Service: 1973 Water Sources: SAR, Imported/Purchased Water

Olive Basin is a former sand and gravel borrow pit that was purchased by the District in 1972 from the State of California, Division of Highways.

Prior to 2007, the basin inflow pipe was positioned so that a significant amount of erosion occurred as the basin was filled. This resulted in poor basin performance because it would clog once the suspended fines settled out. To rectify this, the District constructed a new inflow pipe so the basin fills from the deepest part of the basin. A pump station was installed in summer 2010 so the basin can be quickly drained and cleaned. These investments have resulted in improved basin performance.

In addition to improving the basin infrastructure, operations staff began supplying water to Olive Basin directly from Warner Basin instead of the Off-River Channel. This supplies Olive Basin with a cleaner source of water with lower total suspended solids (TSS) concentrations. The change in water source along with improved infrastructure resulted in increased recharge in 2010-11, which was almost 74 percent above the 5-year average.

Table 4-13 summarizes the monthly recharge provided by Olive Basin in 2010-11.

Table 4-13 Monthly Recharge in Olive Basin, 2010-11 Month Recharge (af) Notes July 2010 0 Empty, Pump station installation August 2010 0 Empty, Pump station installation September 2010 248 October 2010 25 November 2010 0 December 2010 648 Inflow from Warner Basin January 2011 494 Inflow from Warner Basin February 2011 175 Inflow from Warner Basin March 2011 177 Inflow from Warner Basin April 2011 187 Inflow from Warner Basin May 2011 632 Inflow from Warner Basin June 2011 376 Inflow from Warner Basin Total 2,962 5-Year Avg 1,706 Average for FY06-07 to FY10-11

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4.14 Five Coves Basins

Key Facts: Wetted Area: 31 acres Maximum Water Depth: 18 feet Maximum Storage Capacity: 346 af Year Placed Into Service: 1975 Water Sources: SAR, Imported/Purchased Water

The Five Coves Basins were part of the main SAR channel prior to completion of the Santa Ana River Water Conservation and Flood Control Project in December 1973. This project included installation of the center levee which created the main SAR channel for flood control and a parallel set of facilities for water conservation, including the Off-River Channel and the Five Coves Basins. Because water supplied to the Five Coves Basins is diverted directly from the SAR, solids loading can be high, particularly during storm events. As a result, these basins serve more as desilting basins than recharge basins.

The Five Coves Basins were off-line in July-November 2010 to allow for construction in Lincoln and Burris Basins; however, some water was diverted for recharge in August 2010. Table 4-14 summarizes the monthly recharge provided by Five Coves Basins in 2010-11.

Table 4-14 Monthly Recharge in Five Coves Basins, 2010-11 Month Recharge (af) Notes July 2010 0 Off-line August 2010 734 September 2010 50 Off-line October 2010 0 Off-line November 2010 0 Off-line December 2010 345 Estimated January 2011 619 Estimated February 2011 188 Estimated March 2011 384 Off-River recharge (310 af) subtracted April 2011 450 Off-River recharge (300 af) subtracted May 2011 123 Based on percolation testing June 2011 119 Based on percolation testing Total 3,012 5-Year Avg 3,415 Average for FY06-07 to FY10-11

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4.15 Lincoln Basin

Key Facts: Wetted Area: 10 acres Maximum Water Depth: 7 feet Maximum Storage Capacity: 60 af Year Placed Into Service: 1976 Water Sources: SAR, Imported/Purchased Water

Lincoln Basin is a small basin that primarily serves to convey water from Five Coves Basins to Burris Basin. The District undertook a project to remove the fine-grained sedimentary layers underlie the basin in an effort to increase the recharge capacity of the basin. This project started in the summer of 2009 and was completed in the fall of 2009. Short-term percolation tests conducted after the project was completed indicated that recharge rates were lower than expected. Staff is continuing to investigate the potential reasons for this, including over- compaction of the fill material.

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4.16 Burris Basin

Key Facts: Wetted Area: 120 acres Maximum Water Depth: 62 feet Maximum Storage Capacity: 2,670 af Year Placed Into Service: 1977 Water Sources: SAR, Imported/Purchased, Santiago Basin

Burris Basin is a large basin that includes a shallow eastern side that is a remnant of the SAR channel and a deeper western side that was a former sand and gravel mine.

Recharge rates for Burris Basin are relatively low given the size of the basin. Reasons for the low recharge rates include large areas in the former gravel mine section of the basin that are covered with low permeability materials, low permeability materials that were used to shore up the basin sidewalls, and the fact that this basin is rarely drained and cleaned. The District completed a two-year project to remove the fine-grained layers in the northern part of the basin to increase the recharge capacity of the basin. This project was completed in December 2010. With the basin being empty for nearly half of the year, total basin recharge for 2010-11 is below average. Recharge reported during construction is percolation of stored water in the basin and some water pumped from Santiago Basins to maintain minimum water levels.

Table 4-15 summarizes the monthly recharge provided by Burris Basin in 2010-11.

Table 4-15 Monthly Recharge in Burris Basin, 2010-11 Month Recharge (af) Notes July 2010 60 No inflow, under construction August 2010 60 No inflow, under construction September 2010 60 No inflow, under construction October 2010 60 Some water from Santiago Basin November 2010 60 Inflow from Santiago Basins December 2010 175 Inflow from SAR January 2011 2,104 Inflow from SAR February 2011 1,213 Inflow from SAR March 2011 1,176 Inflow from SAR April 2011 982 Inflow from SAR May 2011 779 Inflow from SAR June 2011 938 Inflow from SAR Total 7,667 5-Year Avg 8,169 Average for FY06-07 to FY10-11

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4.17 River View Basin

Key Facts: Wetted Area: 3.6 acres Maximum Water Depth: 4 feet Maximum Storage Capacity: 11 af Year Placed Into Service: 2003 Water Sources: SAR, Imported/Purchased, Santiago Basin

River View Basin is located on the eastern side of the SAR channel across from Burris Basin. Water is provided to the basin via the Santiago pipeline. Typically during the winter months, pumped SAR water from the Burris Basin pump station is supplied to the basin. In the summer months, pumped water from the Santiago Basins is supplied to the basin.

Due to problems with the Santiago Basin pump station, the District rented pumps to have Santiago Basins dewatered from July to December 2010. The rental pumps pumped water from the basin surface unlike the pump station, which draws water off the basin bottom. The chemistry of the water at the surface versus at depth likely contributed to the large difference in recharge performance seen in River View Basin, which was able to recharge an all time record amount of 3,152 acre-feet in 2010-11.

Table 4-16 summarizes the monthly recharge provided by River View Basin in 2010-11.

Table 4-16 Monthly Recharge in River View Basin, 2010-11 Month Recharge (af) Notes July 2010 318 Inflow from Santiago Basins August 2010 251 Inflow from Santiago Basins September 2010 499 Inflow from Santiago Basins October 2010 244 Inflow from Santiago Basins November 2010 383 Inflow from Santiago Basins December 2010 199 Inflow from Santiago Basins January 2011 208 Inflow from Burris Basin February 2011 221 Inflow from Burris Basin March 2011 122 Inflow from Burris Basin April 2011 245 Inflow from Burris Basin May 2011 95 Inflow from Burris Basin, Cleaned June 2011 367 Inflow from Santiago and Burris Basin Total 3,152 5-Year Avg 1,705 Average for FY06-07 to FY10-11

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4.18 Santiago Basins

Key Facts: Wetted Area: 187 acres Maximum Water Depth: 136 feet Maximum Storage Capacity: 13,720 af Year Placed Into Service: 1990 Water Sources: SAR, Imported/Purchased, Santiago Creek

Santiago Basins are three former gravel and sand mines called Smith Pit, Blue Diamond Pit and Bond Pit (see Figure 2-2) that were purchased by OCWD in 1983-85. The combined storage capacity of the basins is over 13,000 acre-feet, which is over half of the total storage capacity of OCWD’s entire surface water recharge system.

December 2010 saw over 8 inches of rain fall at OCWD’s Field Headquarters in less than one week. Even more rain was received in the Santiago Creek watershed. So much rain, in fact, that Irvine Lake spilled and releases from downstream Villa Park Dam to Santiago Basins were in excess of 3,000 cfs for over a week. These releases caused Santiago Basins, which were essentially empty, to fill completely and begin spilling within one week. Local runoff continued to supply Santiago Basins with water until April 2011. This was a truly historic event with some areas in the Santiago Creek watershed experiencing a 100- year event. Total 2010-11 recharge was 17 percent above the recent 5-year average.

Table 4-17 summarizes the monthly recharge provided by the Santiago Basins in 2010-11.

Table 4-17 Monthly Recharge in Santiago Basins, 2010-11 Month Recharge (af) Notes July 2010 1,392 Being dewatered August 2010 965 Being dewatered September 2010 570 Being dewatered, Villa Park releases October 2010 309 Being dewatered November 2010 0 Being dewatered December 2010 2,460 Local runoff, Villa Park releases January 2011 7,037 Local runoff, Villa Park releases February 2011 6,090 Local runoff March 2011 6,203 Local runoff April 2011 5,489 Inflow from Burris Basin May 2011 5,108 Inflow from Burris Basin June 2011 4,583 Inflow from Burris Basin Total 40,206 5-Year Avg 34,302 Average for FY06-07 to FY10-11

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4.19 Santiago Creek Channel

Key Facts: Wetted Area: 2.6 acres Maximum Water Depth: N/A Maximum Storage Capacity: N/A Year Placed Into Service: 2000 Water Sources: SAR, Imported/Purchased, Santiago Creek

The upstream portion of Santiago Creek below Villa Park Dam drains into the Santiago Basins. So unless Santiago Basins are spilling, which can occur during wet years, upstream discharges of local runoff to the creek are captured and recharged in Santiago Basins. The downstream portion of Santiago Creek is generally fed by water pumped to the creek by OCWD.

Typically water discharged to the creek in the winter months is pumped SAR water from the Burris Basin pump station. When there is sufficient local rainfall, discharge to the creek is curtailed or stopped to allow for the recharge of local runoff and to minimize discharges through Hart Park. During the summer months, water supplied to the creek is pumped water from Santiago Basins.

In December 2010, the Santiago Basins were filled with local runoff and spilled. As a result, local runoff supplied water to Santiago Creek from late December 2010 to early January 2011. From early January to June 2011, SAR water from the Burris Basin pump station was recharged in the creek. For 2010-11, total recharge in Santiago Creek was 35 percent above the recent 5-year average.

Table 4-18 summarizes the monthly recharge provided by Santiago Creek in 2010-11.

Table 4-18 Monthly Recharge in Santiago Creek Channel, 2010-11 Month Recharge (af) Notes July 2010 491 Inflow from Santiago Basins August 2010 501 Inflow from Santiago Basins September 2010 806 Inflow from Santiago Basins October 2010 498 Inflow from Santiago Basins November 2010 287 Inflow from Santiago Basins December 2010 290 Inflow from Villa Park Dam releases January 2011 227 Inflow from Burris Basin February 2011 174 Inflow from Burris Basin March 2011 123 Inflow from Burris Basin April 2011 180 Inflow from Burris Basin May 2011 282 Inflow from Burris Basin June 2011 268 Inflow from Burris and Santiago Basins Total 4,127 5-Year Avg 3,052 Average for FY06-07 to FY10-11

36

Section 5 Seawater Barrier Recharge

This section summarizes the operation of the seawater barrier facilities in 2010-11.

5.1 Talbert Gap Seawater Barrier

To hold back seawater intrusion in the Talbert Gap, the District constructed the Talbert Gap Seawater Barrier (Talbert Barrier) in the mid-1970s in the city of Fountain Valley (Figure 5- 1). The Talbert Barrier currently has 36 injection sites with 108 injection well casings. Some of the older injection well sites have a large borehole with multiple injection well casings completed at different depths. Newer injection wells are single casings installed in a single borehole.

Historically, a mixture of recycled water, potable imported water, and groundwater has been used to supply the Talbert Barrier. From 1976 to June 2004, recycled water was produced by Water Factory 21 (WF21). Since January 2008, recycled water has been supplied to the barrier by the Groundwater Replenishment System (GWRS).

Total injection at the Talbert Barrier in 2010-11 was 33,734 acre-feet, which is significantly higher than 10-year average of 19,176 acre-feet per year (see Table B-10 in Appendix B). Virtually all of the water injected in 2010-11 was recycled water. The higher rate of injection 37

over the past several years is mainly due to the lack of clogging caused by the GWRS water compared to sources used previously as well as refinements made to how the barrier wells are operated.

Figure 5-2 shows annual injection at the Talbert Barrier over the last 10 years. Table B-10 in Appendix B presents the data used to prepare this graph. Table B-11 in Appendix B presents the monthly injection at theTalbert Barrier for 2010-11.

40,000 Groundwater 35,000 Recycled Water Imported Water 30,000

25,000

20,000 Avg. 19,176 afy

15,000 Annual Recharge (af) Recharge Annual 10,000

5,000

0 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09 2009-10 2010-11 Year

Figure 5-2 Annual Injection at the Talbert Barrier, 2001-11

5.2 Alamitos Gap Seawater Barrier

The first segment of the Alamitos Barrier was designed and constructed in 1965 to create a freshwater pressure ridge intended to protect the groundwater supplies of both the Orange Country groundwater basin and Central Basin in Los Angeles County from seawater intrusion. As shown in Figure 5-3, the barrier straddles the Orange-Los Angeles County line and spans the approximately 1.8-mile wide Alamitos Gap between Bixby Ranch Hill and Landing Hill. The barrier is comprised of 43 injection wells and more wells are added as needed to minimize further seawater intrusion. Since the barrier straddles the LA-OC county line, only a third of total injection recharges the Orange County groundwater basin.

38

Total injection at the Alamitos Barrier in 2010-11 was 5,073 acre-feet, which is approximately equal to the recent 10-year average of 5,135 acre-feet per year (see Table B- 12 in Appendix B) (LACDPW, 2011). Of the water injected, 1,691 acre-feet was injected on the Orange County side of the barrier. This is approximately equal to the recent 10-year average of 1,707 acre-feet per year recharged into the Orange County side of the barrier.

Figure 5-4 shows annual injection to the Orange County groundwater basin from the Alamitos Barrier from 2001 to 2011. Table B-12 in Appendix B presents the data used to prepare this graph. Table B-13 in Appendix B presents the monthly injection at the Alamitos Barrier for 2010-11.

39

3,000 Imported Water Recycled Water 2,500 Note: Only recharge to OC groundwater basin is shown.

2,000

Avg. 1,707 afy 1,500

1,000 Annual Recharge(af)

500

0 2001-02 2002-03 2003-04 2004-05 2010-11 2005-06** 2006-07** 2007-08** 2008-09** 2009-10** **Data adjusted by LACDPW. Year

Figure 5-4 Annual Injection at the Alamitos Barrier, 2001-11

40

Section 6 In-Lieu Recharge

Since the in-lieu program was put into place by MWD in 1977, the District has recharged over 920,000 acre-feet of imported water as shown on Figure 6-1. The program is administered by the Municipal Water District of Orange County (MWDOC) and is the most successful in-lieu program in MWD’s service territory. When surplus water is available from MWD, OCWD initiates the program and asks groundwater pumpers to turn off their wells and take treated, imported water in-lieu of groundwater. Pumpers that participate in the program are paid by OCWD to make the water cost equivalent to the cost of pumping groundwater.

MWD suspended the in-lieu program in May 2007. In May 2010, MWD reinstated the in-lieu program when it made 225,000 acre-feet of discounted replenishment water available for recharge on a first-come-first serve basis to all agencies within its service area. OCWD immediately started deliveries and was able to recharge 10,435 acre-feet in 2010-11. Table B-14 in Appendix B presents the data used to prepare Figure 6-1.

100,000

90,000

80,000

70,000

60,000

50,000

40,000

Annual Recharge(af) 30,000

20,000

10,000

0 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991* 1992* 1993* 1994* 1995* 1996* 1997* 1998* 1999* 2000* 2001* 2002* 2003* 2004* 2005* 2006* 2007* 2008* 2009* 2010* 2011*

*1991-2011, July 1-June 30, Other years Oct. 1 - Sept. Year

Figure 6-1 Annual In-Lieu Recharge, 1978-2011

41

Section 7 Recharge Summary

This section summarizes the sources used to recharge the basin and the facilities used to recharge these sources in 2010-11.

7.1 Recharge Sources

A total of 19.95 inches of rain was received at the District’s Anaheim Field Headquarters in 2010-11 (OCWD fiscal year ending June 30), which is approximately 37 percent above the historical average of 14.5 inches and is the second consecutive year of above average rainfall. What made 2010-11 notable was that over half of this rainfall occurred in December 2010 with approximately 8 inches falling in a one week period. The remainder of the year saw average to below average rainfall.

The extreme December 2010 rains resulted in a record volume of over 90,000 acre-feet of water captured behind Prado Dam, most of which, was released to the ocean. The rain received in the Santiago Creek watershed was a 100-year event which caused Irvine Lake to spill and resulted in releases of up to 3,000 cubic feet per second from Villa Park Dam to the Santiago Basins. In December 2010, the Santiago Basins were nearly empty, containing over 11,000 acre-feet of storage space after having been pumped down all summer and fall. The releases from Villa Park Dam filled the Santiago Basins in one week period. Combined, storm flow capture from the SAR and Santiago Creek totaled 80,087 acre-feet, which is well above the recent 10-year average of 57,460 acre-feet.

The above average rainfall also resulted in above-average incidental recharge, which totaled 94,484 acre-feet in 2010-11. This is well above the recent 10-year average of 65,951 acre-feet and supplied 25 percent of the total recharge to the basin in 2010-11.

Since 2004-05, Santa Ana River base flows have declined over 33 percent; however, flows appear to have leveled off with the 2010-11 flow of 104,472 acre-feet slightly higher than 2009-10 flow of 102,599 acre-feet. Compared to recent 10-year average, 2010-11 Santa Ana River base flow is 20 percent below average. The decline is attributed to increased conservation by upstream agencies, increased recycling, and reduced economic activity in upper watershed.

Imported water recharge was 39 percent below the 10-year average even though discounted replenishment water was made available in May 2011. For the second year in a row, recycled water recharge exceeded the previous record, and reached 66,795 acre-feet in 2010-11. As has been the case in recent years, recycled water recharge has largely off- set the reduced recharge of imported water and reduced SAR base flow (see Figure 7-3).

Figure 7-1 shows the monthly contribution of recharge sources in 2010-11. This figure shows that storm flow recharge dominates during the winter months (December-April). Recycled water from the GWRS provided a steady and significant recharge source throughout the year. A large increase in imported water recharge occurs in May and June 2011 when MWD made discounted replenishment water available for the first time since May 2007. Table B-17 in Appendix B presents the data used to prepare Figure 7-1.

42

60,000 Incidental Recharge Recycled Water 50,000 Imported/Purchased Water Storm Flow/Local Water 40,000 SAR Base Flow

30,000

20,000 Monthly Recharge(af)

10,000

0 Jul-10 Apr-11 Oct-10 Jun-11 Jan-11 Feb-11 Mar-11 Nov-10 Dec-10 Aug-10 Sep-10 May-11 Month

Figure 7-1 Total Monthly Recharge by Source, 2010-11

In 2010-11, SAR base flow provided 27 percent of total recharge, with SAR storm flow and local inflow providing 21 percent. Taken together, SAR and local flows provided 48 percent of total recharge to the basin. Imported water provided 10 percent of total recharge while recycled water provided 17 percent. Incidental recharge was above average and provided 25 percent of total recharge to the basin. Figure 7-2 shows the relative contribution of each recharge source in 2010-11.

43

SAR Base Flow Storm Flow/Local Water Imported/Purchased Water Recycled Water Incidental Recharge 94,484 af Volumes are in acre-feet 25% 104,469 af 27%

66,795 af 17% 80,087 af 21% 39,053 af 10%

Figure 7-2 Recharge Sources, 2010-11

Total recharge to the basin in 2010-11 was 384,888 acre-feet, which is 12 percent greater than the recent 10-year average of 344,354 acre-feet per year. Table 7-1 summarizes the recharge sources to the basin in 2010-11 and how they compare to the recent 10-year average. Figure 7-3 shows how total recharge in 2010-11 compared to the last 10 years. Tables B-17 and B-18 in Appendix B present the data used to prepare Table 7-1, Figure 7-1 and Figure 7-3.

44

Table 7-1 Recharge Source Summary Source FY10-11 10-Year Avg Increase/ % Increase/ (af) (af) (Decrease) (Decrease) (af) SAR Base Flow (1) 104,469 130,754 (26,285) (20) Storm Flow/Local Water (2) 80,087 57,460 22,627 39 Imported/Purchased Water 39,053 65,568 (26,515) (40) Groundwater (3) 0 2,144 (2,144) (100) Recycled Water (4) 66,795 22,477 44,318 197 Total OCWD Recharge (5) 290,404 278,403 12,001 4 Incidental Recharge 94,484 65,951 28,533 35 Grand Total 384,888 344,354 40,534 12 (1) SAR Base Flow based on OCWD data, which may differ slightly from the SAR Watermaster (see Section 3.2). (2) Storm flow includes SAR storm flow and local inflow to the recharge system below Prado Dam. (3) Groundwater was used to augment the injection supply at the Talbert Barrier until July 2006. (4) Recycled water is produced by the GWRS as well as the Leo J. Vander Lans Water Treatment Facility, which is operated by the Long Beach Water Department. Water from the Vander Lans plant is recharged at the Alamitos Barrier. (5) Recharge at all OCWD facilities, also referred to as Managed Aquifer Recharge (MAR).

600,000 Incidental Recharge Groundwater 500,000 Recycled Water Imported/Purchased Water Storm Flow/Local Water SAR Base Flow 400,000

Avg. 344,350 afy

300,000

200,000 Annual Recharge (af)

100,000

0 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09 2009-10 2010-11 Fiscal Year

Figure 7-3 Total Annual Recharge by Source, 2001-11

45

7.2 Recharge Facilities

In 2010-11, the surface water recharge system provided 80 percent of recharge, seawater barriers provided 12 percent and in-lieu recharge provided the remaining 4 percent, as shown in Figure 7-4.

The recharge of SAR and local water in the surface water recharge system was only 2 percent below the recent 10-year average in 2010-11 due to above average storm flow recharge. Recharge of imported water in the surface water system was 12 percent above the recent 10-year average due to purchases of imported water and recharge to fill MWD storage account (CUP). Recharge of recycled water in the surface water recharge system was an all time high of 32,450 acre-feet. In-lieu recharge is below average due to the unavailability of discounted replenishment water from May 2007 to May 2010. Seawater Barrier recharge continues to be higher than average due to sustained high injection rates achieved with the ultra-pure GWRS water and operational improvements. Table 7-2 summarizes the contribution of the different recharge facilities to basin recharge in 2010-11 and how they compare to the recent 10-year average.

Surface Water System: SAR/Local Water Surface Water System: Imported/Purchased Water Surface Water System: Recycled Water (GWRS) In-Lieu System Seawater Barrier System

35,425 af Volumes are in acre-feet 12%

10,435 af 4%

32,450 af 11%

27,539 af 184,556 af 9% 64%

Figure 7-4 Recharge by Facility, 2010-11

46

Table 7-2 Recharge Facility Summary Facility FY10-11 10-Year Increase/ % (af) Avg (af) (Decrease) Increase/ (af) (Decrease) Surface Water System: SAR/Local Water 184,556 188,214 (3,685) (2) Surface Water System: Imported/Purchased Water 27,539 24,642 2,897 12 Surface Water System: Recycled Water (GWRS)* 32,450 9,504 22,946 241 In-Lieu System 10,435 35,311 (24,876) (70) Seawater Barrier System 35,425 20,883 14,542 70 Total OCWD Recharge 290,405 278,554 11,851 4 * Recharge of recycled water from GWRS in surface water system started in January 2008.

Figure 7-5 shows how recharge at each of the facilities has varied over the past 10 years. Table B-18 in Appendix B presents the data used to prepare Figures 7-4 and 7-5 and Table 7-2.

450,000 Seawater Barrier System In-Lieu System Surface Water System: Recycled Water (GWRS) 400,000 Surface Water System: Imported/Purchased Water Surface Water System:SAR/Local Water 350,000

300,000 Avg. 278,550 af 250,000

200,000

150,000 Annual Recharge (af)

100,000

50,000

0 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09 2009-10 2010-11 Fiscal Year

Figure 7-5 Total Annual Recharge by Facility, 2001-11

47

Section 8 References

California Department of Water Resources (DWR), 1967. Progress Report on the Groundwater Geology of the Coastal Plain of Orange County.

Los Angles County Department of Public Works (LACDPW), 2011. Alamitos Barrier Project, Annual Report on the Control of Seawater Intrusion, 2010-11.

Orange County Flood Control District (OCFCD), 1975*. Carbon Creek System Manual. *Publication date estimated.

Orange County Water District (OCWD), 2001. Approve and authorize agreement D99-177 for GWRS pipeline construction with OCFCD for use of the OCFCD Santa Ana River right- of-way for construction of the GWRS pipeline. OCWD Board Resolution R01-8-124, August 15, 2001. Agreement No. D99-177 was approved by OCFCD on Oct. 23, 2001. In addition to other things, this agreement formalized the use of Miller Basin by OCWD and requires preparation of a Water Conservation Plan.

Orange County Water District (OCWD), 2003a. A History of Orange County Water District. Published by OCWD.

Orange County Water District (OCWD), 2003b. Orange County Water District Recharge Study. December 2003.

Orange County Water District (OCWD), 2003c. Miller Retarding Basin (facility E02B01) Water Conservation Plan. OCFCD and OCWD, September 2003. Approved by OCWD Board in October 2003 (R03-10-143).

Orange County Water District (OCWD), 2004. Groundwater Management Plan. March 2004.

Orange County Water District (OCWD), 2007. Report on Evaluation of Orange County Groundwater Basin Storage and Operational Strategy. Prepared by Tim Sovich, P.E., and Roy Herndon, P.G., February 2007.

Santa Ana River (SAR) Watermaster, 2011. Fortieth Annual Report of the Santa Ana River Watermaster for Water Year Oct. 1, 2009 to Sept. 30, 2010. April 30,2011. Santa Ana River Watermaster for Orange County Water District vs. City of Chino et al., Case No. 117628- County of Orange.

Santa Ana River (SAR) Watermaster, 2012. Forty-First Annual Report of the Santa Ana River Watermaster for Water Year Oct. 1, 2010 to Sept. 30, 2011. June 30,2012. Santa Ana River Watermaster for Orange County Water District vs. City of Chino et al., Case No. 117628-County of Orange.

48

US Army Corps of Engineers (USACOE), 1994. Water Control Manual. Prado Dam & Reservoir, Santa Ana River, California. Prepared by USACOE, Los Angeles District, Reservoir Regulation Section (CESPL-ED-HR). September 1994.

US Army Corps of Engineers (USACOE), 2002. Interim Water Control Plan (During Construction). Prado Dam & Reservoir, Santa Ana River, Orange County, California. Prepared by USACOE, Los Angeles District, Reservoir Regulation Section (CESPL-ED- HR). November 2002.

US Fish and Wildlife Service (USFWS), 2000. Letter to Colonel John P. Carroll, District Engineer, USACOE, Los Angeles District, Re: Formal Section 7 Consultation on the Prado Basin Water Conservation and Water Control Operations Project, Prado Basin, Riverside and San Bernardino Counties, California (Biological Opinion 1-6-99-F-75). Prepared by Loren Hays and signed by Jim A. Bartel, Assistant Field Supervisor. February 10, 2000.

Warrick, Jonathan A., and David M. Rubin, 2007. Suspended-sediment rating curve response to urbanization and wildfire, Santa Ana River, California. Journal of Geophysical Research, Vol. 112, F02018.

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50

Appendix A

Acronyms/Definitions

af. Acre-foot. The amount of water needed to cover an acre of land with one foot of water (43,560 cubic feet, 325,900 gallons).

afy. Acre-feet per year.

Base flow. The portion of river surface flow which remains after deduction of storm flow and/or purchased imported water.

cfs. Cubic-feet-per-second. Measure of water flow in a channel. Equivalent to 450 gallons per minute. In one 24-hour period, a flow of 1 cfs equals 1.98 acre- feet of water.

Ft msl. Elevation in feet mean sea level.

GWRS. Groundwater Replenishment System.

LACDPW. Los Angeles County Department of Public Works.

MWD. Metropolitan Water District of Southern California.

MWDOC. Municipal Water District of Orange County.

OCFCD. Orange County Flood Control District.

OCWD. Orange County Water District.

SAR. Santa Ana River.

Storm flow. The portion of river surface flow that is attributed to rainfall.

SWRCB. California State Water Resources Control Board.

USACOE. United States Army Corps of Engineers.

USGS. United States Geological Survey.

WRD. Water Replenishment District of Southern California.

Appendix B

Data Tables

The data presented in the tables within this appendix were derived from the following sources:

Santa Ana River Watermaster

Each year the SAR Watermaster prepares a report for the Superior Court of Orange County that presents the findings for the prior water year (WY, Oct. 1 to Sept. 30). The SAR Watermaster uses the final USGS record for the SAR below Prado Dam (Station No. 11074000) to determine the daily volume of base flow and storm flow that arrived at Prado Dam.

Orange County Water District

As part of its aquifer recharge operations, OCWD collects a wide variety of data. Each of these data sources and their limitations are described in this section.

Precipitation/Evaporation

OCWD has been collecting precipitation data at its Anaheim Field Headquarters location since 1963. Formerly included in OCFCD’s annual report, it was assigned Station no. 174. Prior to 2007, precipitation was measured using a National Weather Service approved non-recording 8- inch rain gage. In 2007, a tipping bucket rain gage was added to determine rainfall intensities and add accuracy. Evaporation data was collected by OCWD staff from 1988 to 2010 using a National Weather Service approved 48-inch evaporation pan. Since 2010, evaporative losses have been calculated using historical averages collected at this location.

Surface Water Flows

A wide variety of methods are used to measure surface water flows in the recharge system, including flumes, weirs, ultrasonic flow meters, propeller meters, and magnetic flow meters. The data collection using these methods is done so according to standard hydrologic techniques. Every effort is made to ensure that the data collected are as accurate as possible. Where possible, flows from one area are cross-checked with flows measured at downstream facilities. Nevertheless, during the course of any year, there are periods when instrumentation problems and rapid changes in flow rates can make accurately identifying the recharge performance of individual facilities difficult, particularly over short time periods.

Recharge Facility Water Levels

Water levels in the recharge facilities are measured using several methods including pressure transducers, air pressure in orifice lines, and staff gages. At many sites, the water levels are collected on a continuous basis and stored electronically. Water level data are used to operate the recharge system and to calculate storage changes. Storage changes, along with inflow and outflow rates, are used to calculate percolation rates.

The water storage vs. water level elevation relationship for each facility is based on digitized topographic maps.

Talbert Gap Seawater Barrier

From 1976 to 2006, water recharged in the Talbert Barrier was measured using a 30-inch differential pressure flow meter. Since 2007, flows have been measured using a 54-inch ultrasonic flow meter.

Incidental Recharge

Incidental recharge is estimated by comparing changes in basin water levels from year to year. Recently, this method has been improved by calculating the change in storage from each of the basins three main aquifer systems.

Imported Water

Volumes of imported water purchased by OCWD for recharge are reported to OCWD by the selling agency, which could include the Municipal Water District of Orange County (MWDOC), Western Municipal Water District, San Bernardino Valley Municipal Water District, and Elsinore Valley Municipal Water District.

Los Angeles County Department of Public Works

The LACDPW provides OCWD with data on the water recharged at the Alamitos Seawater Barrier. Because the Alamitos Barrier straddles the Los Angeles and Orange County lines, the LACDPW presents the volume of water recharged on both sides of the county line in its annual report on the control of seawater intrusion at the Alamitos Gap. Table B-1 Monthly Rainfall at OCWD Field Headquarters, 1963-2011 OCFCD* Station 172 Rainfall in inches per month YEAR JULY AUG SEPT OCT NOV DEC JAN FEB MAR APR MAY JUNE TOTAL 1963-64 0 0 0 0.98 3.8 0 1.41 0 1.74 0.45 0.03 0 8.41 1964-65 0 0 0 0.12 1.36 1.05 0.5 0.24 2.51 4.44 0 0 10.22 1965-66 0 0.01 0.5 0 7.15 3.72 0.73 1.9 0.26 0 0 0 14.27 1966-67 0 0 0.09 0.05 1.42 6.63 3.78 0 2.12 3.78 0.01 0.03 17.91 1967-68 0 0 0.52 0 1.94 1.73 0.77 0.59 3.22 0.57 0.06 0 9.40 1968-69 0.35 0 0 0.2 0.47 1.41 12.69 9.55 1.44 0.77 0.05 0 26.93 1969-70 0.01 0 0 0 2.17 0.17 2.14 1.25 3.02 0.06 0 0 8.82 1970-71 0 0 0 0 3.57 3.57 0.65 0.48 0.39 0.27 0.18 0.04 9.15 1971-72 0 0 0 0.2 0.39 6.17 0 0.13 0 0.21 0.11 0.14 7.35 1972-73 0 0.15 0.05 0.33 3.36 2.27 3.45 5.37 3.39 0 0 0 18.37 1973-74 0 0 0 0 1.88 0.18 6.09 0.3 3.81 0.28 0.19 0 12.73 1974-75 0 0 0 0.4 0 4.01 0.16 3.1 3.79 1.48 0 0 12.94 1975-76 0 0 0 0.26 0.25 0.15 0 3.58 1.75 1.01 0.04 0.26 7.30 1976-77 0 0 2.4 0 0.61 0.47 3.04 0.82 1.48 0 2.26 0 11.08 1977-78 0 2.25 0 0 0 5.01 9.1 8.3 8.3 2.21 0 0 35.17 1978-79 0 0 1.02 0 1.92 2.64 6.72 3.27 6.07 0 0 0 21.64 1979-80 0 0.38 0 0.9 0.36 0.4 8.49 10.98 3.94 0.35 0.2 0 26.00 1980-81 0 0 0 0 0 0.59 2.82 1.46 3.47 0.49 0.05 0 8.88 1981-82 0 0 0 0.64 2.05 0.46 2.77 1.03 5.98 1.03 0.15 0.06 14.17 1982-83 0 0 0.64 0.27 4.36 1.73 3.64 4.9 9.33 2.88 0.27 0 28.02 1983-84 0 0.61 0.36 3.38 2.59 1.9 0.13 0 0.14 0.43 0 0 9.54 1984-85 0 0 0.38 0.1 2.06 5.06 1.63 1.78 0.77 0 0.09 0 11.87 1985-86 0 0 0.23 0.16 4.17 0.5 1.51 5.33 3.24 0.9 0 0 16.04 1986-87 0.17 0 1.65 0.3 1.52 0.35 2.86 1.09 0.91 0.16 0 0 9.01 1987-88 0 0.05 0 1.67 0.9 2.56 1.61 0.8 0.4 1.99 0 0 9.98 1988-89 0 0.05 0.12 0 0.41 4.41 0.76 1.35 0.9 0 0 0 8 1989-90 0 0 0.5 0.44 0.32 0 2.26 3.24 0.21 0.58 0.76 0.03 8.34 1990-91 0 0 0 0 0.39 0.07 1.68 2.75 6.54 0.07 0 0 11.5 1991-92 0.01 0 0.02 0.34 0.02 1.59 1.84 7.13 5.72 0.3 0 0 16.97 1992-93 0.23 0 0 0.75 0 5.59 12.27 5.74 1.93 0 0 1.26 27.77 1993-94 0 0 0 0.02 0.56 0.95 0.51 4.76 2.34 0.87 0.42 0 10.43 1994-95 0 0 0 0.11 0.73 0.81 12.79 1.33 5.51 0.78 0.22 1.11 23.39 1995-96 0.03 0 0 0 0.04 0.87 1.23 5.41 2.94 0.48 0 0 11 1996-97 0 0 0 1.11 3.36 3.87 5.35 0.26 0 0 0 0 13.95 1997-98 0 0 0.76 0.01 1.71 5.53 3.16 12.06 3.4 1.21 3.35 0.02 31.21 1998-99 0 0 0 0.03 1.48 1.04 1.2 0.68 0.95 1.77 0 0.18 7.33 1999-00 0.05 0 0 0 0.04 0 0.88 4.88 2.11 1.19 0 0 9.15 2000-01 0 0 0.14 1.08 0.3 0.07 4.36 8.64 0.68 0.87 0.06 0.02 16.22 2001-02 0.02 0 0 0 1.74 1.15 0.78 0.14 0.64 0.25 0.23 0 4.95 2002-03 0 0 0 0.14 1.91 2.53 0.18 4.71 2.96 1.67 0.76 0 14.86 2003-04 0.14 0 0 0 0.76 1.11 0.41 5.72 0.75 0.69 0 0 9.58 2004-05 0 0 0 8.45 1.3 3.12 10.58 8.87 1.38 1.48 1.01 0 36.19 2005-06 0 0 0.35 0.71 0.02 0.19 1.64 2.02 3.13 2.13 0.96 0 11.15 2006-07 0.07 0 0 0.14 0.1 0.63 0.03 1.08 0.13 0.35 0 0 2.53 2007-08 0 0 0.32 0.63 0.03 2.06 4.96 1.33 0.07 0.00 0.52 0 9.92 2008-09 0 0 0.06 0 1.96 3.85 0.68 3.68 0.34 0.10 0 0.1 10.77 2009-10 0 0 0 0.7 0 2.75 7.12 5.03 0.59 1.14 0 0 17.33 2010-11 0 0 0 2.35 1.1 10.45 0.8 2.18 2.42 0.03 0.57 0.05 19.95 AVG 0.02 0.07 0.21 0.56 1.39 2.20 3.17 3.32 2.44 0.83 0.26 0.07 14.54 MAX 0.35 2.25 2.4 8.45 7.15 10.45 12.79 12.06 9.33 4.44 3.35 1.26 36.19 Cum Avg. 0.02 0.10 0.31 0.87 2.26 4.45 7.62 10.94 13.38 14.21 14.47 14.54 *Orange County Flood Control District. Guage is maintained by OCWD staff and data reported to OCFCD. Table B-2 Annual Incidental Recharge, 2001-11 Fiscal Year (Jul-June) Net Incidental Recharge* (afy) 2001-02 37,555 2002-03 57,731 2003-04 58,747 2004-05 158,733 2005-06 38,671 2006-07 14,172 2007-08 46,826 2008-09 69,352 2009-10 83,239 2010-11 94,484 10-Yr Avg 65,951 *Losses to Los Angeles County are subtracted from total incidental recharge to yield net incidental recharge. Table B-3 Monthly Local Inflow Summary, 2010-11 Local Storm Flow to Local Storm Flow Direct Rainfall to Total Local Inflow SAR Below Imperial Captured in Recharge Basins Captured and Rubber Dam (1) Santiago Basins (2) (3) Recharged (af/mo) (af/mo) (af/mo) (af/mo) Jul-10 0 56 0 56 Aug-10 0 362 0 362 Sep-10 0 552 0 552 Oct-10 300 350 98 748 Nov-10 200 250 46 496 Dec-10 1,353 13,337 435 15,125 Jan-11 300 3,093 33 3,426 Feb-11 350 992 91 1,433 Mar-11 300 3,255 101 3,656 Apr-11 10 65 1 76 May-11 10 65 24 99 Jun-11 0 65 2 67 Total 2,823 22,442 831 26,096 (1) Includes estimated flow from Carbon Canyon Diversion. Local storm flow below Imperial Dam is assumed to be captured. Lost SAR water assumed to originate above Prado Dam. (2) Includes inflow from Santiago Creek and releases from Villa Park Dam (Table B-6). December 2010 losses to ocean of 988 af is subtracted (see Table B-9). (3) Assumes direct rainfall to 500 acres of recharge basins. Table B-4 Annual SAR Watermaster Base Flow and Storm Flow, 1936-2011 (1)

Total SAR Oct-Sept Water Year SAR Base Flow SAR Storm Flow Supply (afy) (afy) (afy) 1935-36 1936 41,670 11,660 53,330 1936-37 1937 44,850 77,260 122,110 1937-38 1938 50,700 178,960 229,660 1938-39 1939 52,550 11,130 63,680 1939-40 1940 52,080 10,150 62,230 1940-41 1941 59,600 114,750 174,350 1941-42 1942 62,780 15,140 77,920 1942-43 1943 62,270 82,410 144,680 1943-44 1944 65,970 43,770 109,740 1944-45 1945 65,590 36,590 102,180 1945-46 1946 60,210 26,690 86,900 1946-47 1947 54,890 29,310 84,200 1947-48 1948 52,120 6,990 59,110 1948-49 1949 44,780 8,550 53,330 1949-50 1950 43,260 6,550 49,810 1950-51 1951 38,050 4,390 42,440 1951-52 1952 38,420 47,490 85,910 1952-53 1953 38,440 7,320 45,760 1953-54 1954 39,840 14,060 53,900 1954-55 1955 40,360 6,130 46,490 1955-56 1956 39,390 11,780 51,170 1956-57 1957 37,040 6,060 43,100 1957-58 1958 37,580 38,580 76,160 1958-59 1959 34,550 2,880 37,430 1959-60 1960 30,600 5,180 35,780 1960-61 1961 26,190 760 26,950 1961-62 1962 27,250 14,840 42,090 1962-63 1963 27,310 6,290 33,600 1963-64 1964 27,540 5,610 33,150 1964-65 1965 27,970 10,100 38,070 1965-66 1966 30,610 44,230 74,840 1966-67 1967 28,990 56,840 85,830 1967-68 1968 32,703 14,659 47,362 1968-69 1969 44,766 330,735 375,501 1969-70 1970 38,856 11,625 50,481 1970-71 1971 38,402 13,462 51,864 1971-72 1972 40,416 11,327 51,743 1972-73 1973 48,999 28,485 77,484 1973-74 1974 43,106 19,405 62,511 1974-75 1975 50,176 11,679 61,855 1975-76 1976 45,627 13,582 59,209 1976-77 1977 48,387 14,566 62,953 1977-78 1978 58,501 194,349 252,850 1978-79 1979 71,863 62,643 134,506 1979-80 1980 82,509 445,251 527,760 1980-81 1981 74,875 26,923 101,798 1981-82 1982 81,548 61,819 143,367 1982-83 1983 111,692 306,519 418,211 1983-84 1984 109,231 55,825 165,056

1 of 2 Table B-4 Annual SAR Watermaster Base Flow and Storm Flow, 1936-2011 (1)

Total SAR Oct-Sept Water Year SAR Base Flow SAR Storm Flow Supply (afy) (afy) (afy) 1984-85 1985 125,023 37,889 162,912 1985-86 1986 127,215 70,158 197,373 1986-87 1987 119,848 23,243 143,091 1987-88 1988 124,104 42,714 166,818 1988-89 1989 119,572 33,171 152,743 1989-90 1990 119,149 24,314 143,463 1990-91 1991 111,151 75,275 186,426 1991-92 1992 106,948 82,729 189,677 1992-93 1993 128,068 438,563 566,631 1993-94 1994 111,186 41,622 152,808 1994-95 1995 123,468 284,651 408,119 1995-96 1996 131,861 58,692 190,553 1996-97 1997 136,676 61,783 198,459 1997-98 1998 155,711 300,604 456,315 1998-99 1999 158,637 23,673 182,310 1999-00 2000 148,269 40,269 188,538 2000-01 2001 153,915 54,621 208,536 2001-02 2002 145,891 10,615 156,506 2002-03 2003 146,113 97,810 243,923 2003-04 2004 143,510 57,317 200,827 2004-05 2005 154,307 469,515 623,822 2005-06 2006 147,736 85,734 233,470 2006-07 2007 129,830 12,901 142,731 2007-08 2008 116,483 68,896 185,379 2008-09 2009 102,711 53,662 156,373 2009-10 2010 103,099 135,775 238,874 2010-11 2011 102,031 205,568 307,599 Maximum 158,637 469,515 623,822 Minimum 26,190 760 26,950 Recent 10-yr Avg. 129,171 119,779 248,950 (1) Data from Santa Ana River Water Master Reports.

2 of 2 Table B-5 Monthly SAR Base and Storm Flow Recharged, 2010-11 (1)

Month SAR Base Flow SAR Storm Flow (2) Total SAR Water Recharged (af/mo) (af/mo) (af/mo) Jul-10 6,783 - 6,783 Aug-10 5,736 - 5,736 Sep-10 6,436 - 6,436 Oct-10 7,209 1,406 8,615 Nov-10 8,625 1,745 10,370 Dec-10 10,558 3,442 14,000 Jan-11 11,746 10,654 22,400 Feb-11 11,559 7,944 19,503 Mar-11 11,491 2,009 13,500 Apr-11 9,151 10,203 19,354 May-11 7,477 7,543 15,020 Jun-11 7,701 9,045 16,746 Totals 104,472 53,991 158,463

(1) OCWD data is used to determine SAR flows except during periods when the inflatable rubber dams are down. SAR base flow numbers shown in italics are based on SAR Watermaster data.

(2) Total storm flow and local water captured and reported elsewhere in this report includes both the SAR component of storm flow and local runoff to the recharge system. Table B-6 Monthly Santiago Creek Inflow, 2010-11 Water Released Total Santiago Creek Santiago from Villa Park Total Santiago Losses to Inflow Captured and Creek Inflow Dam Creek Inflow Ocean (1) Recharged (af/mo) (af/mo) (af/mo) (af/mo) (af/mo) Jul-10 56 0 56 0 56 Aug-10 48 314 362 0 362 Sep-10 60 492 552 0 552 Oct-10 350 0 350 0 350 Nov-10 250 0 250 0 250 Dec-10 1,558 12,767 14,325 988 13,337 Jan-11 123 2,970 3,093 0 3,093 Feb-11 250 742 992 0 992 Mar-11 522 2,733 3,255 0 3,255 Apr-11 65 0 65 0 65 May-11 65 0 65 0 65 Jun-11 65 0 65 0 65 Totals 3,412 20,018 23,430 988 22,442 Note: Santiago Creek inflow is categorized as storm flow, even though it may include nuisance flow during the summer months and releases from Villa Park Dam. (1) See Table B-9 Table B-7 Monthly Recharge of Imported and Purchased Water, 2010-11 (af) Surface Water Recharge In-Lieu Recharge Seawater Barrier Recharge WMWD Total MWD Total MWD OC-28 MWD OC-28A Arlington Surface OCWD In- In-Lieu In-Lieu Talbert Alamitos Total Barrier Month OC-59 OC-28 (CUP*) OC-28A (CUP*) Desalter Recharge Lieu (CUP*) Recharge Barrier Barrier Recharge Grand Total Jul-10 0 0 3,248 0 0 0 3,248 0 0 0 4 78 82 3,330 Aug-10 0 0 3,661 0 0 0 3,661 0 0 0 11 59 70 3,731 Sep-10 0 0 5,299 0 0 0 5,299 0 0 0 68 59 126 5,426 Oct-10 0 0 2,543 0 0 0 2,543 0 0 0 8 78 86 2,629 Nov-10 0 1,677 0 0 0 0 1,677 0 0 0 4 114 118 1,795 Dec-10 00 0 0 0 000000797979 Jan-11 00 0 0 0 000000 102 102 102 Feb-11 05 0 0 0 050000 96 96 101 Mar-11 0700 2 0 0720002 126 128 201 Apr-11 00 0 0 0 000003747777 May-11 0 0 724 0 518 0 1,243 2,308 0 2,308 0 47 47 3,598 Jun-11 50 9,234 506 0 0 0 9,791 8,128 0 8,128 0 67 67 17,986 Totals 50 10,986 15,982 2 518 0 27,539 10,435 0 10,435 100 979 1,079 39,053 Notes: Imported water is purchased from MWD (from outside SAR watershed). Purchased water is from WMWD (from within SAR watershed) OC-28 only provides CRA water from Lake Matthews. OC-28A provides a mix of SWP and CRA water OC-59 provides SWP water. *MWD Conjunctive Use Program (CUP) Table B-8 Monthly Recharge of Recycled Water, 2010-11

Surface Water Alamitos Barrier Total Recycled Month Recharge System Talbert Barrier (1) Water (af/mo) (af/mo) (af/mo) (af/mo) Jul-10 2,142 3,763 47 5,952 Aug-10 2,183 3,703 63 5,948 Sep-10 1,767 3,012 53 4,832 Oct-10 2,154 3,393 78 5,624 Nov-10 2,854 2,906 58 5,818 Dec-10 4,090 2,242 95 6,427 Jan-11 3,565 2,143 51 5,759 Feb-11 2,145 2,384 70 4,599 Mar-11 1,818 2,395 32 4,246 Apr-11 2,958 2,408 86 5,452 May-11 3,290 2,844 41 6,175 Jun-11 3,483 2,440 41 5,964 Totals 32,450 33,634 712 66,795

Note: (1) Only that portion of Alamitos Gap Barrier recharge attributed to the Orange County groundwater basin is shown. Table B-9 Monthly Losses to Ocean and Evaporation, 2010-11 Losses to Ocean in SAR Losses to Ocean Losses to Ocean Evaporation (1) in Santiago Creek in Carbon Creek Losses (2) Total Losses (af/mo) (af/mo) (af/mo) (af/mo) (af/mo) Jul-10 0 0 0 290 290 Aug-10 0 0 0 292 292 Sep-10 0 0 0 208 208 Oct-10 50 0 0 167 217 Nov-10 100 0 0 167 267 Dec-10 76,000 988 0 125 77,113 Jan-11 65,000 0 0 125 65,125 Feb-11 13,000 0 0 125 13,125 Mar-11 12,000 0 0 125 12,125 Apr-11 2,500 0 0 167 2,667 May-11 0 0 0 208 208 Jun-11 0 0 0 208 208 Total 168,650 988 0 2,207 171,845 (1) As measured by OCWD at Ball Road guage. (2) Evaporation losses estimated to occur over 500 wetted acres. These losses are not accounted for in the overall total recharge calculations due to the small value and uncertainty related to the estimate. Table B-10 Annual Injection for Talbert Barrier, 1991-2011 Fiscal Year Imported Water Recycled Water Groundwater Total (Jul-Jun) (afy) (afy) (afy) (afy) 1991-92 0 6,829 8,193 15,022 1992-93 0 8,161 6,695 14,856 1993-94 0 5,042 3,937 8,979 1994-95 0 2,738 2,614 5,353 1995-96 0 3,068 2,330 5,397 1996-97 0 1,814 1,272 3,086 1997-98 0 2,153 1,706 3,859 1998-99 0 3,489 2,543 6,031 1999-00 0 5,773 4,837 10,610 2000-01 941 1,630 8,242 10,812 2001-02 2,656 4,143 7,186 13,985 2002-03 1,490 3,867 5,708 11,065 2003-04 5,072 1,784 4,094 10,950 2004-05 10,821 4,155 2,920 17,897 2005-06 6,506 4,086 1,169 11,761 2006-07 7,534 218 358 8,110 2007-08 4,581 10,072 0 14,653 2008-09 4,140 28,952 0 33,092 2009-10 177 36,333 0 36,510 2010-11 100 33,634 0 33,734 Total 44,018 167,940 63,805 275,763 Annual Avg.* 4,002 8,397 3,190 13,788 10-Yr. Avg. 4,308 12,724 2,144 19,176 *Imported water average starts in 2000. Table B-11 Monthly Injection for Talbert Barrier, 2010-11 Recycled Water Imported Water Total (af/mo) (af/mo) (af/mo) Jul-10 3,763 3.9 3,767 Aug-10 3,703 11.0 3,714 Sep-10 3,012 67.8 3,080 Oct-10 3,393 8.3 3,401 Nov-10 2,906 4.1 2,910 Dec-10 2,242 0.0 2,242 Jan-11 2,143 0.0 2,143 Feb-11 2,384 0.0 2,384 Mar-11 2,395 2.3 2,398 Apr-11 2,408 3.0 2,411 May-11 2,844 0.1 2,844 Jun-11 2,440 0.0 2,440 Total 33,634 100 33,734 Table B-12 Annual Injection for Alamitos Barrier, 1991-2011 OC total LAC (WRD) Total Fiscal Year (June-July) OC Total LAC (WRD) Total Grand Total OC Recycled* OC Imported LAC Recycled* LAC Imported Recycled Total* Imported Total (afy) (afy) (afy) (afy) (afy) (afy) (afy) (afy) (afy) 1991-92 1,589 4,168 5,758 0 1,589 0 4,168 0 5,758 1992-93 1,614 3,627 5,241 0 1,614 0 3,627 0 5,241 1993-94 1,433 2,712 4,145 0 1,433 0 2,712 0 4,145 1994-95 798 2,697 3,496 0 798 0 2,697 0 3,496 1995-96 1,692 3,651 5,342 0 1,692 0 3,651 0 5,342 1996-97 1,885 3,854 5,739 0 1,885 0 3,854 0 5,739 1997-98 1,614 3,722 5,336 0 1,614 0 3,722 0 5,336 1998-99 1,494 3,837 5,330 0 1,494 0 3,837 0 5,330 1999-00 1,874 4,294 6,070 0 1,874 0 4,294 0 6,070 2000-01 1,673 3,721 5,393 0 1,673 0 3,721 0 5,393 2001-02 2,282 3,780 6,062 0 2,282 0 3,780 0 6,062 2002-03 1,449 3,564 5,012 0 1,449 0 3,564 0 5,012 2003-04 1,938 3,964 5,878 0 1,938 0 3,964 0 5,878 2004-05 1,915 3,151 5,066 0 1,915 0 3,151 0 5,066 2005-06** 888 2,631 3,458 304 584 872 1,699 1,176 2,282 2006-07** 616 650 1,265 181 435 126 524 307 959 2007-08** 1,850 4,121 5,971 421 1,430 874 3,247 1,295 4,677 2008-09** 2,721 5,216 7,936 616 2,105 1,103 4,113 1,719 6,217 2009-10** 1,720 3,909 5,629 717 1,003 1,584 2,325 2,301 3,329 2010-11 1,691 3,382 5,073 712 979 1,432 1,950 2,144 2,929 Total 32,733 70,650 103,200 2,949 29,784 5,991 64,598 8,940 94,260 Annual Avg. 1,637 3,532 5,160 492 1,489 998 3,230 1,490 4,713 10-Yr Avg. 1,707 3,437 5,135 295 1,412 599 2,832 894 4,241 Source: LACDPW *ABP did not use recycled water until October, 2005. **Note that volumes changed from FY09-10 report based on adjustments made to Point C flow meter corrections by LACDPW. Annual averages for recycled water use starts in FY05-06. Table B-13 Monthly Injection for Alamitos Barrier*, 2010-11 Recycled Water Imported Water Total (af/mo) (af/mo) (af/mo) Jul-10 47 78 125 Aug-10 63 59 121 Sep-10 53 59 111 Oct-10 78 78 155 Nov-10 58 114 171 Dec-10 95 79 174 Jan-11 51 102 153 Feb-11 70 96 166 Mar-11 32 126 158 Apr-11 86 74 160 May-11 41 47 88 Jun-11 41 67 108 Total 712 979 1,690.5 *Only injection attributed to the OC groundwater basin is shown. Table B-14 Annual In-Lieu Recharge of Imported Water, 1978-2011 Year In-lieu Recharge of Imported Water (afy) 1977-78 48,290 1978-79 23,792 1979-80 24,861 1980-81 36,373 1981-82 0 1982-83 0 1983-84 52,822 1984-85 25,198 1985-86 0 1986-87 0 1987-88 18,856 1988-89 15,022 1989-90 38,961 1990-91* 44,588 1991-92* 39,789 1992-93* 38,900 1993-94* 48,134 1994-95* 15,622 1995-96* 5,542 1996-97* 7,883 1997-98* 15,096 1998-99* 13,352 1999-00* 38,007 2000-01* 18,640 2001-02* 19,472 2002-03* 61,463 2003-04* 52,168 2004-05* 69,617 2005-06* 89,239 2006-07* 50,740 2007-08* 0 2008-09* 0 2009-10* 0 2010-11* 10,435 Totals 922,862 10-Yr. Avg. 35,314 From 1977-1990, Year ending Sept. 30. * Year Ending June 30 From Column C of Section 4 of Basic Data, OCWD Engineer's Report. Table B-15 Monthly In-Lieu Recharge of Imported Water, 2010-11 Month OCWD In-Lieu MWD In-Lieu (CUP*) Totals (af/mo) (af/mo) (af/mo) Jul-10 0 0 0 Aug-10 0 0 0 Sep-10 0 0 0 Oct-10 0 0 0 Nov-10 0 0 0 Dec-10 0 0 0 Jan-11 0 0 0 Feb-11 0 0 0 Mar-11 0 0 0 Apr-11 0 0 0 May-11 2,308 0 2,308 Jun-11 8,128 0 8,128 Totals 10,435 0 10,435

*MWD Conjunctive Use Program Table B-16 Annual Recharge by Source, 2001-11 Total SAR and Total Subtototal of Fiscal Year Storm Flow/Local Recycled Groundwater Incidental SAR Base Flow (1) other Local Imported/Purchase OCWD Total Recharge (July-June) Water Water (2) Recharge Water (1) Water Recharge (3) (afy) (afy) (afy) (afy) (afy) (afy) (afy) (afy) (afy) 2001-02 145,891 24,327 170,218 67,610 4,143 7,186 249,157 37,555 286,712 2002-03 146,113 49,098 195,211 108,553 3,867 5,708 313,339 57,731 371,070 2003-04 143,510 41,119 184,629 84,166 1,784 4,094 274,672 58,747 333,419 2004-05 154,307 80,072 234,379 86,732 4,155 2,920 328,186 158,733 486,919 2005-06 147,736 89,097 236,833 107,286 4,341 1,169 349,629 38,671 388,300 2006-07 133,338 36,090 169,428 102,805 368 358 272,959 14,172 287,131 2007-08 124,090 60,670 184,760 9,887 18,142 0 212,789 46,826 259,615 2008-09 105,490 53,007 158,497 28,000 54,674 0 241,170 69,352 310,522 2009-10 102,599 61,035 163,634 21,586 66,506 0 251,726 83,239 334,965 2010-11 104,469 80,087 184,556 39,053 66,795 0 290,404 94,484 384,888 Totals 1,307,543 574,601 1,882,144 655,677 224,774 21,436 2,784,031 659,510 3,443,542 10 year Avg. 130,754 57,460 188,214 65,568 22,477 2,144 278,403 65,951 344,354 Avg.Percent of Total 55% 19% 7% 1% 81% 19% (1) Recharge of SAR and other Local Water based on monthly reports prepared by OCWD Recharge Operations staff and may differ from what is reported by the SAR Watermaster. (2) Deep aquifer groundwater used for injection at the Talbert Barrier, which was stopped in August 2006. (3) Recharge due to the activity of OCWD (aka Artificial Recharge). Table B-17 Monthly Recharge Source Summary, 2010-11 Local Water Imported/Purchased Water Recycled Water Storm Subtotal Subtotal SAR Base Flow/Local Subtotal Surface Talbert Alamitos In-Lieu Import/Purchase Surface Talbert Alamitos Recycled Incidental Grand Month Flow (1) Water (2) Local Water Recharge Barrier Barrier (3) Recharge Water Recharge Barrier Barrier (2) Water Recharge (4) Total (af/mo) (af/mo) (af/mo) (af/mo) (af/mo) (af/mo) (af/mo) (af/mo) (af/mo) (af/mo) (af/mo) (af/mo) (af/mo) (af/mo) Jul-10 6,783 56 6,839 3,248 476 0 3,328 2,142 3,763 47 5,952 7,874 23,992 Aug-10 5,736 362 6,098 3,661 11 60 0 3,732 2,183 3,703 63 5,948 7,874 23,651 Sep-10 6,436 552 6,988 5,299 68 59 0 5,426 1,767 3,012 53 4,832 7,874 25,119 Oct-10 7,209 2,154 9,363 2,543 878 0 2,629 2,154 3,393 78 5,624 7,874 25,490 Nov-10 8,625 2,241 10,866 1,677 4 115 0 1,796 2,854 2,906 58 5,818 7,874 26,353 Dec-10 10,558 18,567 29,125 0 079 0 79 4,090 2,242 95 6,427 7,874 43,505 Jan-11 11,746 14,080 25,826 0 0 102 0 102 3,565 2,143 51 5,759 7,874 39,560 Feb-11 11,556 9,377 20,933 5 096 0 101 2,145 2,384 70 4,599 7,874 33,507 Mar-11 11,491 5,665 17,156 72 2 126 0 201 1,818 2,395 32 4,246 7,874 29,476 Apr-11 9,151 10,279 19,430 0 374 0 77 2,958 2,408 86 5,452 7,874 32,832 May-11 7,477 7,642 15,119 1,243 0472,308 3,598 3,290 2,844 41 6,175 7,874 32,765 Jun-11 7,701 9,112 16,813 9,791 0678,128 17,986 3,483 2,440 41 5,964 7,874 48,637 Totals 104,469 80,087 184,556 27,539 100 978 10,435 39,053 32,450 33,634 712 66,795 94,484 384,888

Note: (1) SAR base flow totals based on OCWD data unless otherwise noted (See Table B-5). (2) Storm flow/local water includes SAR storm flow originating above Prado Dam, local SAR inflow below Prado Dam, Santiago Creek inflow, precipitation to water surfaces. Storm flow totals only show what portion of storm flow that was captured and recharged. (3) Only that portion of Alamitos Gap Barrier recharge attributed to the Orange County groundwater basin is shown. (4) The annual estimated incidental recharge is divided evenly over the 12 months of the year. Table B-18 Annual Recharge by Facility, 2001-11 Surface Water Recharge System Total Seawater Fiscal Year Storm Total In-Lieu Total OCWD SAR Base Recycled Surface Barrier (July-June) Flow/Local SAR/Local Imported/Pur System Recharge (3) Flow Water Water System (2) Water Water (1) chase Water Recharge (afy) (afy) (afy) (afy) (afy) (afy) (afy) (afy) (afy) 2001-02 145,891 24,327 170,218 43,200 0 213,417 19,472 16,267 249,157 2002-03 146,113 49,098 195,211 44,151 0 239,362 61,463 12,514 313,339 2003-04 143,510 41,119 184,629 24,987 0 209,616 52,168 12,888 274,672 2004-05 154,307 80,072 234,379 4,378 0 238,757 69,617 19,812 328,186 2005-06 147,736 89,097 236,833 10,986 0 247,819 89,216 12,649 349,684 2006-07 133,338 36,090 169,428 44,147 0 213,575 50,740 8,726 273,041 2007-08 124,090 60,670 184,760 4,149 7,722 196,631 0 16,504 213,135 2008-09 105,490 53,007 158,497 22,237 25,248 205,982 0 35,813 241,795 2009-10 102,599 61,035 163,634 20,642 29,617 213,893 0 38,230 252,123 2010-11 104,469 80,087 184,556 27,539 32,450 244,545 10,435 35,425 290,405 Totals 1,307,543 574,601 1,882,144 246,416 95,037 2,223,597 353,112 208,828 2,785,537 10 year Avg. 130,754 57,460 188,214 24,642 9,504 222,360 35,311 20,883 278,554 Percent of Total 68% 9% 0% 80% 13% 7% (1) Recharge of SAR and other Local Water based on monthly reports prepared by OCWD Recharge Operations Staff. May differ from what is reported by the SAR Watermaster. (2) Only that portion of Alamitos Gap Barrier recharge attributed to the Orange County groundwater basin is shown. (3) This is recharge due solely to OCWD activities. Does not include incidental recharge.

Appendix C

Monthly Forebay Percolation Efficiency Reports

FOREBAY PERCOLATION EFFICIENCY REPORT July-10

Actual Remarks RIVER SYSTEM 4,671 Average perc of 76 cfs DESILTING SYSTEM 60 Estimated based on observations OFF-RIVER SYSTEM 59 Used only 4 days WARNER SYSTEM 1 500 Includes Foster Huckleberry and Conrock basins OLIVE BASIN2 0 Empty ANAHEIM LAKE1,935 Inflow from Little Warner and OC-28 MINI-ANA LAKE583 Inflow from Little Warner and OC-28 KRAEMER BASIN122 Used only a few days MILLER BASIN2,156 Inflow from GWR LA JOLLA BASIN635 Inflow from Little Warner and OC-28 PLACENTIA BASIN3 0 Not in use RAYMOND BASIN3 300 Inflow from Little Warner and OC-28 FIVE COVES BASIN0 Empty BURRIS BASIN60 No inflow RIVER VIEW BASIN318 Inflow from Santiago SANTIAGO BASINS 1,392 SANTIAGO CREEK491 Inflow from Santiago TOTALS 13,282

TABLE 1 TABLE 2 AVAILABLE FLOWS TO RECHARGE SYSTEMS (AF) LOSSES FROM RECHARGE SYSTEM (AF) Imperial Headgates (used Water Master data) 6,783 Est'd SAR flow past Chapman Ave. 0 GWRS 2,142.27 OC-11 (MWD) 0 Est'd Santiago Cr. flow to SAR 0 OC-28 (MWD) 3,247.90 Est'd flows past Raymond Basin 0 OC-28a (MWD) 0 Est'd local Forebay inflow below Imperial4 Calc'd evap (inches) Estimated 6.95 Est'd local Santiago inflow 56 Est'd evaporative losses5 290 Irvine lake releases (OC-13 MWD) 0 Villa Park Dam releases Precip at Warner Basin (inches) 0 Precip direct to open water surfaces5 0 TOTAL INFLOW 12,229 TOTAL LOSSES 290

TABLE 3 STORAGE CHANGES (AF) SUMMARY Facility Begin End Net Deep basins 6,569 7,342 773 TOTAL INFLOW (TABLE 1) 12,229 Santiago Pits 9,198 7,082 -2,116 TOTAL LOSSES (TABLE 2) 290 River 0 STORAGE CHANGE 6 (TABLE 3) -1,343 Off-river 0 CALC'D PERCOLATION 13,282

Irvine Lake TOTAL 15,767 14,424 -1,343 NOTES: 1) Warner system includes est monthly perc values for Foster-Huckleberry and Conrock basins. 2) No instrumentation in Olive Basin; perc estimated. 3) Placentia and Raymond are County of Orange RDMD flood control basins. 4) Carbon Diversion included. 5) Estimated Precipitation and Evaporation is based on 500 acres of open water surface. 6) Net "negative" storage is water volume moving from basins to underground recharge. PERCOLATION BASIN MONTHLY SUMMARY JULY 2010 (values in acre-feet)

Facility Storage Storage Maximum Total Max Avg Avg W.S. 1 Start End Storage Perc Perc Perc Elev Desilting Ponds2,3 230 230 230 60 0 0 Fos-Huckleberry2,3 520 501 630 na na Conrock Basin3,4 904 877 1,060 na na Warner Basin 2,426 2,435 2,600 500 na na 238.1 Little Warner 187 188 210 na na na na Olive Pit2 0 0 183 0 na na na Anaheim Lake 1,374 2,173 2,300 1,935 100 62 214.9 Mini-Anaheim Lk 0 10 21 583 0 0 na Miller Basin 265 250 340 2,156 75 70 216.3 Kraemer Basin 47 5 1,050 122 16 2 169.5 La Jolla Basin 1.00 4.80 635 48 36 200.0 Placentia Basin2 5 5 75 0 0 0 na Raymond Basin2 10 163 162 300 0 0 na Five Coves Basins 0 0 700 0 na na na Burris Pit 600 500 2,670 60 2 2 148.2 Santiago (Bond) 6,106 4,881 8,690 1,392 60 46 249.3 Santiago (Blu Dia)5 3,092 2,201 5,240 249.3 Deep Basin Totals 15,767 14,424 26,161 7,743

Prado Dam6 0 0 25,000

NOTES: 1) "Avg W.S." is feet above Mean Sea Level. 2) Some values estimated where lack of instrumentation precludes calculation. 3) Warner system includes Foster-Huckleberry and Conrock basins. 4) Periodic discharge from YLWD's well #11 into Conrock Basin unaccounted for. 5) Storage in Blu Dia includes Smith Pit. Above elev 235, Santiago Pits respond as one basin. 6) Prado dam storage values provided by U.S. Army Corps of Engineers.

"na" indicates data not available. FOREBAY PERCOLATION EFFICIENCY REPORT August-10

Actual Remarks RIVER SYSTEM 3,933 Average perc of 64 cfs (only used 1/3 of river) DESILTING SYSTEM 30 Estimated based on observations OFF-RIVER SYSTEM 250 Diverted above 5 Coves dam WARNER SYSTEM 1 500 Includes Foster Huckleberry and Conrock basins OLIVE BASIN2 0 Empty ANAHEIM LAKE897 Dewatered for pump cable repair and cleaning MINI-ANA LAKE522 Inflow from OC-28 KRAEMER BASIN2,821 Inflow from Anaheim and OC-28 MILLER BASIN2,212 Inflow from GWR LA JOLLA BASIN899 Inflow from Anaheim and OC-28 PLACENTIA BASIN3 0 Not in use RAYMOND BASIN3 511 Inflow from Anaheim and OC-28 FIVE COVES BASIN734 Empty BURRIS BASIN60 No inflow RIVER VIEW BASIN251 Inflow from Santiago SANTIAGO BASINS 965 SANTIAGO CREEK501 Inflow from Santiago TOTALS 15,086

TABLE 1 TABLE 2 AVAILABLE FLOWS TO RECHARGE SYSTEMS (AF) LOSSES FROM RECHARGE SYSTEM (AF) Imperial Headgates (used water Master data) 5,736 Est'd SAR flow past Chapman Ave. 0 GWRS 2,183.15 OC-11 (MWD) 0 Est'd Santiago Cr. flow to SAR 0 OC-28 (MWD) 3,661.06 Est'd flows past Raymond Basin 0 OC-28a (MWD) 0 Est'd local Forebay inflow below Imperial4 Calc'd evap (inches) Estimated 7 Est'd local Santiago inflow 48 Est'd evaporative losses5 292 Irvine lake releases (OC-13 MWD) 0 Villa Park Dam releases 314 Precip at Warner Basin (inches) 0 Precip direct to open water surfaces5 0 TOTAL INFLOW 11,942 TOTAL LOSSES 292

TABLE 3 STORAGE CHANGES (AF) SUMMARY Facility Begin End Net Deep basins 7,342 5,310 -2,032 TOTAL INFLOW (TABLE 1) 11,942 Santiago Pits 7,082 5,679 -1,403 TOTAL LOSSES (TABLE 2) 292 River 0 STORAGE CHANGE 6 (TABLE 3) -3,435 Off-river 0 CALC'D PERCOLATION 15,086

Irvine Lake TOTAL 14,424 10,989 -3,435 NOTES: 1) Warner system includes est monthly perc values for Foster-Huckleberry and Conrock basins. 2) No instrumentation in Olive Basin; perc estimated. 3) Placentia and Raymond are County of Orange RDMD flood control basins. 4) Carbon Diversion included. 5) Estimated Precipitation and Evaporation is based on 500 acres of open water surface. 6) Net "negative" storage is water volume moving from basins to underground recharge. PERCOLATION BASIN MONTHLY SUMMARY August-10 (values in acre-feet)

Facility Storage Storage Maximum Total Max Avg Avg W.S. 1 Start End Storage Perc Perc Perc Elev Desilting Ponds2,3 230 100 230 60 0 0 Fos-Huckleberry2,3 501 520 630 na na Conrock Basin3,4 877 893 1,060 na na Warner Basin 2,435 2,408 2,600 500 na na 238.1 Little Warner 188 184 210 na na na na Olive Pit2 0 0 183 0 na na na Anaheim Lake 2,173 0 2,300 897 72 30 203.1 Mini-Anaheim Lk 10 0 21 522 0 0 na Miller Basin 250 220 340 2,212 74 72 215.9 Kraemer Basin 5 334 1,050 2,821 160 92 180.9 La Jolla Basin 4.80 0.83 899 52 30 200.6 Placentia Basin2 5 5 75 0 0 0 na Raymond Basin2 163 100 162 511 0 0 na Five Coves Basins 0 105 700 734 na na na Burris Pit 500 440 2,670 60 2 2 147.1 Santiago (Bond) 4,881 4,061 8,690 965 na 26 237.1 Santiago (Blu Dia)5 2,201 1,618 5,240 237.4 Deep Basin Totals 14,424 10,989 26,161 10,181

Prado Dam6 0 0 25,000

NOTES: 1) "Avg W.S." is feet above Mean Sea Level. 2) Some values estimated where lack of instrumentation precludes calculation. 3) Warner system includes Foster-Huckleberry and Conrock basins. 4) Periodic discharge from YLWD's well #11 into Conrock Basin unaccounted for. 5) Storage in Blu Dia includes Smith Pit. Above elev 235, Santiago Pits respond as one basin. 6) Prado dam storage values provided by U.S. Army Corps of Engineers.

"na" indicates data not available. FOREBAY PERCOLATION EFFICIENCY REPORT September-10

Actual Remarks RIVER SYSTEM 4,905 Average perc 81 cfs DESILTING SYSTEM 15 Estimated based on observations OFF-RIVER SYSTEM 298 Diverted above 5 Coves dam WARNER SYSTEM 1 551 Includes Foster Huckleberry and Conrock basins OLIVE BASIN2 248 Ran test ANAHEIM LAKE0 Dewatered for pump cable repair and cleaning MINI-ANA LAKE100 Inflow from OC-28 KRAEMER BASIN4,101 Inflow from Warner and OC-28 MILLER BASIN1,946 Inflow from GWR LA JOLLA BASIN424 Inflow from Warner and OC-28 PLACENTIA BASIN3 0 Not in use RAYMOND BASIN3 564 Inflow from Warner and OC-28 FIVE COVES BASIN50 Empty BURRIS BASIN60 No inflow RIVER VIEW BASIN499 Inflow from Santiago SANTIAGO BASINS570 Inflow from Villa Park SANTIAGO CREEK806 Inflow from Santiago TOTALS 15,137

TABLE 1 TABLE 2 AVAILABLE FLOWS TO RECHARGE SYSTEMS (AF) LOSSES FROM RECHARGE SYSTEM (AF) Imperial Headgates (used Water Master data) 6,436 Est'd SAR flow past Chapman Ave. 0 GWRS 1,766.73 OC-11 (MWD) 0 Est'd Santiago Cr. flow to SAR 0 OC-28 (MWD) 5,299.20 Est'd flows past Raymond Basin 0 OC-28a (MWD) 0 Est'd local Forebay inflow below Imperial4 Calc'd evap (inches) Estimated 5 Est'd local Santiago inflow (estimated) 60 Est'd evaporative losses5 208 Irvine lake releases (OC-13 MWD) 0 Villa Park Dam releases (estimated) 492 Precip at Warner Basin (inches) 0 Precip direct to open water surfaces5 0 TOTAL INFLOW 14,054 TOTAL LOSSES 208

TABLE 3 STORAGE CHANGES (AF) SUMMARY Facility Begin End Net Deep basins 5,310 5,401 91 TOTAL INFLOW (TABLE 1) 14,054 Santiago Pits 5,679 4,296 -1,383 TOTAL LOSSES (TABLE 2) 208 River 0 STORAGE CHANGE 6 (TABLE 3) -1,292 Off-river 0 CALC'D PERCOLATION 15,137

Irvine Lake TOTAL 10,989 9,697 -1,292 NOTES: 1) Warner system includes est monthly perc values for Foster-Huckleberry and Conrock basins. 2) No instrumentation in Olive Basin; perc estimated. 3) Placentia and Raymond are County of Orange RDMD flood control basins. 4) Carbon Diversion included. 5) Estimated Precipitation and Evaporation is based on 500 acres of open water surface. 6) Net "negative" storage is water volume moving from basins to underground recharge. PERCOLATION BASIN MONTHLY SUMMARY September-10 (values in acre-feet)

Facility Storage Storage Maximum Total Max Avg Avg W.S. 1 Start End Storage Perc Perc Perc Elev Desilting Ponds2,3 100 50 230 60 0 0 Fos-Huckleberry2,3 520 525 630 na na Conrock Basin3,4 893 900 1,060 na na Warner Basin 2,408 2,544 2,600 551 na na 237.6 Little Warner 184 204 210 na na na na Olive Pit2 0 0 183 248 na na na Anaheim Lake 0 0 2,300 0 0 0 168.0 Mini-Anaheim Lk 0 5 21 100 0 0 na Miller Basin 220 9 340 1,946 72 66 213.2 Kraemer Basin 334 677 1,050 4,101 164 134 196.1 La Jolla Basin 0.83 2.10 424 24 14 200.2 Placentia Basin2 5 5 75 0 0 0 na Raymond Basin2 100 100 162 564 0 0 na Five Coves Basins 105 0 700 50 na na na Burris Pit 440 380 2,670 60 2 2 145.5 Santiago (Bond) 4,061 2,747 8,690 570 na na na Santiago (Blu Dia)5 1,618 1,549 5,240 na Deep Basin Totals 10,989 9,697 26,161 8,674

Prado Dam6 0 0 25,000

NOTES: 1) "Avg W.S." is feet above Mean Sea Level. 2) Some values estimated where lack of instrumentation precludes calculation. 3) Warner system includes Foster-Huckleberry and Conrock basins. 4) Periodic discharge from YLWD's well #11 into Conrock Basin unaccounted for. 5) Storage in Blu Dia includes Smith Pit. Above elev 235, Santiago Pits respond as one basin. 6) Prado dam storage values provided by U.S. Army Corps of Engineers.

"na" indicates data not available. FOREBAY PERCOLATION EFFICIENCY REPORT October-10

Actual Remarks RIVER SYSTEM 5,025 Average perc 82 cfs DESILTING SYSTEM 30 Estimated based on observations OFF-RIVER SYSTEM 307 Diverted above 5 Coves dam WARNER SYSTEM 1 600 Includes Foster Huckleberry and Conrock basins OLIVE BASIN2 25 ANAHEIM LAKE 1,587 Just cleaned MINI-ANA LAKE 229 Inflow from Warner and OC-28 KRAEMER BASIN 2,334 Inflow from Warner and OC-28 MILLER BASIN1,812 Inflow from GWR LA JOLLA BASIN326 Inflow from Warner and OC-28 PLACENTIA BASIN3 0 Not in use RAYMOND BASIN3 357 Inflow from Warner and OC-28 FIVE COVES BASIN0 Empty BURRIS BASIN60 Pumped flow from Santiago to raise level a bit RIVER VIEW BASIN244 Inflow from Santiago SANTIAGO BASINS309 Inflow from local runoff SANTIAGO CREEK498 Inflow from Santiago TOTALS 13,743

TABLE 1 TABLE 2 AVAILABLE FLOWS TO RECHARGE SYSTEMS (AF) LOSSES FROM RECHARGE SYSTEM (AF) Imperial Headgates (used Watermaster data) 8,665 Est'd SAR flow past Chapman Ave. 50 GWRS 2,153.99 OC-11 (MWD) 0 Est'd Santiago Cr. flow to SAR 0 OC-28 (MWD) 2,542.90 Est'd flows past Raymond Basin 0 OC-28a (MWD) 0 Est'd local Forebay inflow below Imperial4 300 Calc'd evap (inches) Estimated 4 Est'd local Santiago inflow (estimated) 350 Est'd evaporative losses5 167 Irvine lake releases (OC-13 MWD) 0 Villa Park Dam releases (estimated) 0 Precip at Warner Basin (inches) 2.35 Precip direct to open water surfaces5 98 TOTAL INFLOW 14,110 TOTAL LOSSES 217

TABLE 3 STORAGE CHANGES (AF) SUMMARY Facility Begin End Net Deep basins 5,401 6,252 851 TOTAL INFLOW (TABLE 1) 14,110 Santiago Pits 4,296 3,595 -701 TOTAL LOSSES (TABLE 2) 217 River 0 STORAGE CHANGE 6 (TABLE 3) 150 Off-river 0 CALC'D PERCOLATION 13,743

Irvine Lake TOTAL 9,697 9,847 150 NOTES: 1) Warner system includes est monthly perc values for Foster-Huckleberry and Conrock basins. 2) No instrumentation in Olive Basin; perc estimated. 3) Placentia and Raymond are County of Orange RDMD flood control basins. 4) Carbon Diversion included. 5) Estimated Precipitation and Evaporation is based on 500 acres of open water surface. 6) Net "negative" storage is water volume moving from basins to underground recharge. PERCOLATION BASIN MONTHLY SUMMARY October-10 (values in acre-feet)

Facility Storage Storage 5025 Total Max Avg Avg W.S. 1 Start End Storage Perc Perc Perc Elev Desilting Ponds2,3 50 230 230 60 0 0 Fos-Huckleberry2,3 525 550 630 na na Conrock Basin3,4 900 940 1,060 na na Warner Basin 2,544 2,442 2,600 607 na na 237.4 Little Warner 204 189 210 na na na na Olive Pit2 0 0 183 25 na na na Anaheim Lake 0 1,090 2,300 1,587 172 134 191.8 Mini-Anaheim Lk 5 5 21 229 0 0 na Miller Basin 9 378 340 1,812 74 58 216.4 Kraemer Basin 677 0 1,050 2,334 154 100 196.0 La Jolla Basin 2.10 3.00 326 na na na Placentia Basin2 5 5 75 0 0 0 na Raymond Basin2 100 40 162 357 0 0 na Five Coves Basins 0 0 700 0 na na na Burris Pit 380 380 2,670 60 2 2 145.5 Santiago (Bond) 2,747 2,083 8,690 309 na na na Santiago (Blu Dia)5 1,549 1,512 5,240 na Deep Basin Totals 9,697 9,847 26,161 7,706

Imperial Headgates 0 324 25,000 8665

NOTES: 1) "Avg W.S." is feet above Mean Sea Level. 2) Some values estimated where lack of instrumentation precludes calculation. 3) Warner system includes Foster-Huckleberry and Conrock basins. 4) Periodic discharge from YLWD's well #11 into Conrock Basin unaccounted for. 5) Storage in Blu Dia includes Smith Pit. Above elev 235, Santiago Pits respond as one basin. 6) Prado dam storage values provided by U.S. Army Corps of Engineers.

"na" indicates data not available. FOREBAY PERCOLATION EFFICIENCY REPORT November-10

Actual Remarks RIVER SYSTEM 4,656 Average perc 79 cfs DESILTING SYSTEM 60 Estimated based on observations OFF-RIVER SYSTEM 300 Diverted above 5 Coves dam WARNER SYSTEM 1 600 Includes Foster Huckleberry and Conrock basins OLIVE BASIN2 0 ANAHEIM LAKE 3,467 Just cleaned MINI-ANA LAKE 276 Inflow from Warner and OC-28 KRAEMER BASIN 2,600 Inflow from Warner, GWR and OC-28 MILLER BASIN1,307 Inflow from GWR LA JOLLA BASIN787 Inflow from Warner and OC-28 PLACENTIA BASIN3 0 Not in use RAYMOND BASIN3 185 Inflow from Warner and OC-28 FIVE COVES BASIN0 Empty BURRIS BASIN60 Some inflow from Santiago RIVER VIEW BASIN383 Inflow from Santiago SANTIAGO BASINS0 Inflow from local runoff SANTIAGO CREEK287 Inflow from Santiago TOTALS 14,968

TABLE 1 TABLE 2 AVAILABLE FLOWS TO RECHARGE SYSTEMS (AF) LOSSES FROM RECHARGE SYSTEM (AF) Imperial Headgates (OCWD) 10,470 Est'd SAR flow past Chapman Ave. 100 GWRS 2,853.94 OC-11 (MWD) 0 Est'd Santiago Cr. flow to SAR 0 OC-28 (MWD) 1,676.97 Est'd flows past Raymond Basin 0 OC-28a (MWD) 0 Est'd local Forebay inflow below Imperial4 200 Calc'd evap (inches) Estimated 4 Est'd local Santiago inflow (estimated) 250 Est'd evaporative losses5 167 Irvine lake releases (OC-13 MWD) 0 Villa Park Dam releases (estimated) 0 Precip at Warner Basin (inches) 1.1 Precip direct to open water surfaces5 46 TOTAL INFLOW 15,497 TOTAL LOSSES 267

TABLE 3 STORAGE CHANGES (AF) SUMMARY Facility Begin End Net Deep basins 6,252 6,909 657 TOTAL INFLOW (TABLE 1) 15,497 Santiago Pits 3,595 3,200 -395 TOTAL LOSSES (TABLE 2) 267 River 0 STORAGE CHANGE 6 (TABLE 3) 262 Off-river 0 CALC'D PERCOLATION 14,968

Irvine Lake TOTAL 9,847 10,109 262 NOTES: 1) Warner system includes est monthly perc values for Foster-Huckleberry and Conrock basins. 2) No instrumentation in Olive Basin; perc estimated. 3) Placentia and Raymond are County of Orange RDMD flood control basins. 4) Carbon Diversion included. 5) Estimated Precipitation and Evaporation is based on 500 acres of open water surface. 6) Net "negative" storage is water volume moving from basins to underground recharge. PERCOLATION BASIN MONTHLY SUMMARY November-10 (values in acre-feet)

Facility Storage Storage Maximum Total Max Avg Avg W.S. 1 Start End Storage Perc Perc Perc Elev Desilting Ponds2,3 230 230 230 60 0 0 Fos-Huckleberry2,3 550 585 630 na na Conrock Basin3,4 940 1,000 1,060 na na Warner Basin 2,442 2,496 2,600 600 na na 236.2 Little Warner 189 187 210 na na na Olive Pit2 0 0 183 0 na na na Anaheim Lake 1,090 1,450 2,300 3,467 130 122 210.6 Mini-Anaheim Lk 5 5 21 276 0 0 na Miller Basin 378 225 340 1,307 na na 210.2 Kraemer Basin 0 366 1,050 2,600 170 94 179.0 La Jolla Basin 3.00 0.00 787 na na na Placentia Basin2 5 5 75 0 0 0 na Raymond Basin2 40 20 162 185 0 0 na Five Coves Basins 0 0 700 0 na na na Burris Pit 380 340 2,670 60 na na na Santiago (Bond) 2,083 1,800 8,690 na na na Santiago (Blu Dia)5 1,512 1,400 5,240 na Deep Basin Totals 9,847 10,109 26,161 9,342

Prado Dam6 324 2,070 25,000

NOTES: 1) "Avg W.S." is feet above Mean Sea Level. 2) Some values estimated where lack of instrumentation precludes calculation. 3) Warner system includes Foster-Huckleberry and Conrock basins. 4) Periodic discharge from YLWD's well #11 into Conrock Basin unaccounted for. 5) Storage in Blu Dia includes Smith Pit. Above elev 235, Santiago Pits respond as one basin. 6) Prado dam storage values provided by U.S. Army Corps of Engineers.

"na" indicates data not available. FOREBAY PERCOLATION EFFICIENCY REPORT December-10

Actual Remarks RIVER SYSTEM 5,912 Average perc 96 cfs DESILTING SYSTEM 60 Estimated based on observations OFF-RIVER SYSTEM 238 Diverted above 5 Coves dam WARNER SYSTEM 1 609 Includes Foster Huckleberry and Conrock basins OLIVE BASIN2 648 Inflow from Warner basin ANAHEIM LAKE2,944 Inflow from Warner basin MINI-ANA LAKE220 Inflow from Anaheim pumps KRAEMER BASIN4,993 Inflow from Anaheim pumps and GWR MILLER BASIN2,222 Inflow from GWR, Carbon Div spilled LA JOLLA BASIN510 Inflow from Anaheim pumps PLACENTIA BASIN3 0 Not in use RAYMOND BASIN3 18 Inflow from Anaheim pumps FIVE COVES BASIN345 Inflow from river valves BURRIS BASIN175 Inflow from SAR RIVER VIEW BASIN199 Inflow from Santiago SANTIAGO BASINS2,460 Inflow from Villa Park dam release and local runoff SANTIAGO CREEK290 Inflow from Santiago TOTALS 21,843

TABLE 1 TABLE 2 AVAILABLE FLOWS TO RECHARGE SYSTEMS (AF) LOSSES FROM RECHARGE SYSTEM (AF) Imperial Headgates (OCWD) Estimated 90,000 Est'd SAR flow past Chapman Ave. 76,000 GWRS 4,089.91 OC-11 (MWD) 0 Est'd Santiago Cr. flow to SAR 988 OC-28 (MWD) 0.00 Est'd flows past Raymond Basin 0 OC-28a (MWD) 0 Est'd local Forebay inflow below Imperial4 1,353 Calc'd evap (inches) Estimated 3 Est'd local Santiago inflow (estimated) 1,558 Est'd evaporative losses5 125 Irvine lake releases (OC-13 MWD) 0 Villa Park Dam releases (estimated) 12,767 Precip at Warner Basin (inches) 10.45 Precip direct to open water surfaces5 435 TOTAL INFLOW 110,203 TOTAL LOSSES 77,113

TABLE 3 STORAGE CHANGES (AF) SUMMARY Facility Begin End Net Deep basins 6,909 7,855 946 TOTAL INFLOW (TABLE 1) 110,203 Santiago Pits 3,200 13,501 10,301 TOTAL LOSSES (TABLE 2) 77,113 River 0 STORAGE CHANGE 6 (TABLE 3) 11,247 Off-river 0 CALC'D PERCOLATION 21,843

Irvine Lake TOTAL 10,109 21,356 11,247 NOTES: 1) Warner system includes est monthly perc values for Foster-Huckleberry and Conrock basins. 2) No instrumentation in Olive Basin; perc estimated. 3) Placentia and Raymond are County of Orange RDMD flood control basins. 4) Carbon Diversion included. 5) Estimated Precipitation and Evaporation is based on 500 acres of open water surface. 6) Net "negative" storage is water volume moving from basins to underground recharge. PERCOLATION BASIN MONTHLY SUMMARY December-10 (values in acre-feet)

Facility Storage Storage Maximum Total Max Avg Avg W.S. 1 Start End Storage Perc Perc Perc Elev Desilting Ponds2,3 230 230 230 60 0 0 Fos-Huckleberry2,3 585 580 630 na na Conrock Basin3,4 1,000 962 1,060 na na Warner Basin 2,496 2,433 2,600 609 na na Little Warner 187 190 210 na na na Olive Pit2 0 77 183 648 na na na Anaheim Lake 1,450 1,668 2,300 2,944 138 100 214.1 Mini-Anaheim Lk 5 0 21 220 na Miller Basin 225 0 340 2,222 100 86 213.6 Kraemer Basin 366 897 1,050 4,993 180 162 200.6 La Jolla Basin 0.00 3.44 510 na na na Placentia Basin2 5 5 75 0 0 0 na Raymond Basin2 20 20 162 18 0 0 na Five Coves Basins 0 168 700 345 na na na Burris Pit 340 622 2,670 175 na na na Santiago (Bond) 1,800 8,346 8,690 2,460 na na na Santiago (Blu Dia)5 1,400 5,155 5,240 na Deep Basin Totals 10,109 21,356 26,161 15,204

Prado Dam6 2,070 73,475 25,000

NOTES: 1) "Avg W.S." is feet above Mean Sea Level. 2) Some values estimated where lack of instrumentation precludes calculation. 3) Warner system includes Foster-Huckleberry and Conrock basins. 4) Periodic discharge from YLWD's well #11 into Conrock Basin unaccounted for. 5) Storage in Blu Dia includes Smith Pit. Above elev 235, Santiago Pits respond as one basin. 6) Prado dam storage values provided by U.S. Army Corps of Engineers.

"na" indicates data not available. FOREBAY PERCOLATION EFFICIENCY REPORT January-11

Actual Remarks RIVER SYSTEM 6,158 Average perc 99 cfs DESILTING SYSTEM 60 Estimated based on observations OFF-RIVER SYSTEM 365 Diverted above 5 Coves dam WARNER SYSTEM 1 422 Includes Foster Huckleberry and Conrock basins OLIVE BASIN2 494 Inflow from Warner basin ANAHEIM LAKE2,640 Inflow from Warner basin MINI-ANA LAKE513 Inflow from Anaheim pumps KRAEMER BASIN3,514 Inflow from Anaheim pumps and GWR MILLER BASIN1,950 Inflow from GWR LA JOLLA BASIN590 Inflow from Anaheim pumps PLACENTIA BASIN3 0 Not in use RAYMOND BASIN3 381 Inflow from Anaheim pumps FIVE COVES BASIN619 Inflow from river valves and Dam diversion BURRIS BASIN2,104 Inflow from SAR RIVER VIEW BASIN208 Inflow from Burris Pit SANTIAGO BASINS7,037 Inflow from Villa Park dam release and local runoff SANTIAGO CREEK227 Inflow from Burris Pit TOTALS 27,282

TABLE 1 TABLE 2 AVAILABLE FLOWS TO RECHARGE SYSTEMS (AF) LOSSES FROM RECHARGE SYSTEM (AF) Imperial Headgates (OCWD) Estimated 87,400 Est'd SAR flow past Chapman Ave. 65,000 GWRS 3,565.23 OC-11 (MWD) 0 Est'd Santiago Cr. flow to SAR 0 OC-28 (MWD) 0.00 Est'd flows past Raymond Basin 0 OC-28a (MWD) 0 Est'd local Forebay inflow below Imperial4 300 Calc'd evap (inches) Estimated 3 Est'd local Santiago inflow (estimated) 123 Est'd evaporative losses5 125 Irvine lake releases (OC-13 MWD) 0 Villa Park Dam releases (estimated) 2,970 Precip at Warner Basin (inches) 0.8 Precip direct to open water surfaces5 33 TOTAL INFLOW 94,392 TOTAL LOSSES 65,125

TABLE 3 STORAGE CHANGES (AF) SUMMARY Facility Begin End Net Deep basins 7,855 10,104 2,248 TOTAL INFLOW (TABLE 1) 94,392 Santiago Pits 8,346 8,224 -122 TOTAL LOSSES (TABLE 2) 65,125 River 0 STORAGE CHANGE 6 (TABLE 3) 2,126 Off-river 0 CALC'D PERCOLATION 27,140

Irvine Lake TOTAL 16,201 18,328 2,126 NOTES: 1) Warner system includes est monthly perc values for Foster-Huckleberry and Conrock basins. 2) No instrumentation in Olive Basin; perc estimated. 3) Placentia and Raymond are County of Orange RDMD flood control basins. 4) Carbon Diversion included. 5) Estimated Precipitation and Evaporation is based on 500 acres of open water surface. 6) Net "negative" storage is water volume moving from basins to underground recharge. PERCOLATION BASIN MONTHLY SUMMARY January-11 (values in acre-feet)

Facility Storage Storage Maximum Total Max Avg Avg W.S. 1 Start End Storage Perc Perc Perc Elev Desilting Ponds2,3 230 230 230 60 00 Fos-Huckleberry2,3 580 580 630 na na Conrock Basin3,4 962 962 1,060 na na Warner Basin 2,433 2,422 2,600 422 na na Little Warner 190 186 210 na na na Olive Pit2 77 88 183 494 27 16 222 Anaheim Lake 1,668 1,833 2,300 2,640 110 84 216.5 Mini-Anaheim Lk 0 15 21 513 na Miller Basin 0 286 340 1,950 94 88 211.3 Kraemer Basin 897 944 1,050 3,514 182 88 213.0 La Jolla Basin 3.44 3.74 590 36 18 201.2 Placentia Basin2 5575 0 00 na Raymond Basin2 20 100 162 381 00 na Five Coves Basins 168 168 700 619 na na na Burris Pit 622 2,281 2,670 2,104 94 68 164.9 Santiago (Bond) 8,346 8,224 8,690 7,037 240 228 284.4 Deep Basin Totals 16,201 18,328 20,921 20,324

Prado Dam6 73,475 9,102 25,000

NOTES: 1) "Avg W.S." is feet above Mean Sea Level. 2) Some values estimated where lack of instrumentation precludes calculation. 3) Warner system includes Foster-Huckleberry and Conrock basins. 4) Periodic discharge from YLWD's well #11 into Conrock Basin unaccounted for. 5) Storage in Blu Dia includes Smith Pit. Above elev 235, Santiago Pits respond as one basin. 6) Prado dam storage values provided by U.S. Army Corps of Engineers.

"na" indicates data not available. FOREBAY PERCOLATION EFFICIENCY REPORT February-11

Actual Remarks RIVER SYSTEM 5,780 Average perc 96 cfs DESILTING SYSTEM 60 Estimated based on observations OFF-RIVER SYSTEM 177 Values estimated WARNER SYSTEM 1 550 Includes Foster Huckleberry and Conrock basins OLIVE BASIN2 175 Inflow from Warner basin ANAHEIM LAKE2,428 Inflow from Warner basin MINI-ANA LAKE342 Inflow from Anaheim pumps KRAEMER BASIN1,702 Inflow from Anaheim pumps and Warner MILLER BASIN2,381 Inflow from GWR LA JOLLA BASIN762 Inflow from Anaheim pumps and Warner PLACENTIA BASIN3 0 Not in use RAYMOND BASIN3 167 Inflow from Anaheim pumps and Warner FIVE COVES BASIN188 Values estimated BURRIS BASIN1,213 Inflow from SAR RIVER VIEW BASIN221 Inflow from Burris Pit SANTIAGO BASINS6,090 Inflow from Villa Park dam release and local runoff SANTIAGO CREEK174 Inflow from Burris Pit TOTALS 22,410

TABLE 1 TABLE 2 AVAILABLE FLOWS TO RECHARGE SYSTEMS (AF) LOSSES FROM RECHARGE SYSTEM (AF) Imperial Headgates (OCWD) Estimated 32,500 Est'd SAR flow past Chapman Ave. 13,000 GWRS 2,145.35 OC-11 (MWD) 0 Est'd Santiago Cr. flow to SAR 0 OC-28 (MWD) 5.00 Est'd flows past Raymond Basin 0 OC-28a (MWD) 0 Est'd local Forebay inflow below Imperial4 350 Calc'd evap (inches) Estimated 3 Est'd local Santiago inflow (estimated) 250 Est'd evaporative losses5 125 Irvine lake releases (OC-13 MWD) 0 Villa Park Dam releases (estimated) 742 Precip at Warner Basin (inches) 2.18 Precip direct to open water surfaces5 91 TOTAL INFLOW 36,083 TOTAL LOSSES 13,125

TABLE 3 STORAGE CHANGES (AF) SUMMARY Facility Begin End Net Deep basins 10,104 10,251 147 TOTAL INFLOW (TABLE 1) 36,083 Santiago Pits 13,379 13,780 401 TOTAL LOSSES (TABLE 2) 13,125 River 0 STORAGE CHANGE 6 (TABLE 3) 548 Off-river 0 CALC'D PERCOLATION 22,410

Irvine Lake TOTAL 23,483 24,031 548 NOTES: 1) Warner system includes est monthly perc values for Foster-Huckleberry and Conrock basins. 2) No instrumentation in Olive Basin; perc estimated. 3) Placentia and Raymond are County of Orange RDMD flood control basins. 4) Carbon Diversion included. 5) Estimated Precipitation and Evaporation is based on 500 acres of open water surface. 6) Net "negative" storage is water volume moving from basins to underground recharge. PERCOLATION BASIN MONTHLY SUMMARY February-11 (values in acre-feet)

Facility Storage Storage Maximum Total Max Avg Avg W.S. 1 Start End Storage Perc Perc Perc Elev Desilting Ponds2,3 230 230 230 60 0 0 Fos-Huckleberry2,3 580 552 630 na na Conrock Basin3,4 962 932 1,060 na na Warner Basin 2,422 2,510 2,600 550 na na Little Warner 186 201 210 na na na Olive Pit2 88 79 183 175 10 6 213 Anaheim Lake 1,833 2,137 2,300 2,428 96 90 220.2 Mini-Anaheim Lk 15 15 21 342 na Miller Basin 286 262 340 2,381 94 64 216.4 Kraemer Basin 944 922 1,050 1,702 70 62 213.8 La Jolla Basin 3.74 12.90 762 36 26 201.2 Placentia Basin2 5 5 75 0 0 0 na Raymond Basin2 100 50 162 167 0 0 na Five Coves Basins 168 168 700 500 na na na Burris Pit 2,281 2,175 2,670 1,213 60 44 168.3 Santiago (Bond) 8,224 8,408 8,690 6,090 240 228 285.0 Santiago (Blu Dia)5 5,155 5,372 5,240 285.0 Deep Basin Totals 23,483 24,031 26,161 16,370

Prado Dam6 9,102 9,782 25,000

NOTES: 1) "Avg W.S." is feet above Mean Sea Level. 2) Some values estimated where lack of instrumentation precludes calculation. 3) Warner system includes Foster-Huckleberry and Conrock basins. 4) Periodic discharge from YLCWD's well #11 into Conrock Basin unaccounted for. 5) Storage in Blu Dia includes Smith Pit. Above elev 235, Santiago Pits respond as one basin. 6) Prado dam storage values provided by U.S. Army Corps of Engineers.

"na" indicates data not available. FOREBAY PERCOLATION EFFICIENCY REPORT March-11

Actual Remarks RIVER SYSTEM 5,722 Average perc 92 cfs DESILTING SYSTEM 60 Estimated based on observations OFF-RIVER SYSTEM 0 SEE 5 COVES WARNER SYSTEM 1 931 Includes Foster Huckleberry and Conrock basins OLIVE BASIN2 177 Inflow from Warner basin ANAHEIM LAKE2,240 Inflow from Warner basin MINI-ANA LAKE340 Inflow from Anaheim pumps KRAEMER BASIN728 Inflow from Anaheim pumps and Warner MILLER BASIN1,755 Inflow from GWR LA JOLLA BASIN409 Inflow from Anaheim pumps and Warner PLACENTIA BASIN3 0 Not in use RAYMOND BASIN3 45 Inflow from Anaheim pumps and Warner FIVE COVES BASIN694 Incudes Off River and Lincoln Basin BURRIS BASIN1,176 Inflow from SAR RIVER VIEW BASIN122 Inflow from Burris Pit SANTIAGO BASINS6,203 Inflow from Villa Park dam release and local runoff SANTIAGO CREEK123 Inflow from Burris Pit TOTALS 20,725

TABLE 1 TABLE 2 AVAILABLE FLOWS TO RECHARGE SYSTEMS (AF) LOSSES FROM RECHARGE SYSTEM (AF) Imperial Headgates (OCWD) Estimated 25,500 Est'd SAR flow past Chapman Ave. 12,000 GWRS 1,818 OC-11 (MWD) 0 Est'd Santiago Cr. flow to SAR 0 OC-28 (MWD) 69.9 Est'd flows past Raymond Basin 0 OC-28a (MWD) 2.4 Est'd local Forebay inflow below Imperial4 300 Calc'd evap (inches) Estimated 3 Est'd local Santiago inflow (estimated) 522 Est'd evaporative losses5 125 Irvine lake releases (OC-13 MWD) 0 Villa Park Dam releases (estimated) 2,733 Precip at Warner Basin (inches) 2.42 Precip direct to open water surfaces5 101 TOTAL INFLOW 31,047 TOTAL LOSSES 12,125

TABLE 3 STORAGE CHANGES (AF) SUMMARY Facility Begin End Net Deep basins 10,251 8,684 -1,567 TOTAL INFLOW (TABLE 1) 31,047 Santiago Pits 13,780 13,544 -236 TOTAL LOSSES (TABLE 2) 12,125 River 0 STORAGE CHANGE 6 (TABLE 3) -1,803 Off-river 0 CALC'D PERCOLATION 20,725

Irvine Lake TOTAL 24,031 22,228 -1,803 NOTES: 1) Warner system includes est monthly perc values for Foster-Huckleberry and Conrock basins. 2) No instrumentation in Olive Basin; perc estimated. 3) Placentia and Raymond are County of Orange RDMD flood control basins. 4) Carbon Diversion included. 5) Estimated Precipitation and Evaporation is based on 500 acres of open water surface. 6) Net "negative" storage is water volume moving from basins to underground recharge. PERCOLATION BASIN MONTHLY SUMMARY MARCH 2011 (values in acre-feet)

Facility Storage Storage Maximum Total Max Avg Avg W.S. 1 Start End Storage Perc Perc Perc Elev Desilting Ponds2,3 230 230 230 60 0 0 Fos-Huckleberry2,3 552 552 630 na na Conrock Basin3,4 932 932 1,060 na na Warner Basin 2,510 2,502 2,600 931 na na Little Warner 201 199 210 na na na Olive Pit2 79 0 183 177 8 6 215 Anaheim Lake 2,137 2,033 2,300 2,240 86 72 222.1 Mini-Anaheim Lk 15 0 21 340 na Miller Basin 262 294 340 1,755 78 44 218.2 Kraemer Basin 922 0 1,050 728 46 20 196.2 La Jolla Basin 12.90 4.78 409 36 12 200.7 Placentia Basin2 5 5 75 0 0 0 na Raymond Basin2 50 5 162 45 0 0 na Five Coves Basins 168 200 700 694 na na na Burris Pit 2,175 1,727 2,670 1,176 46 38 166.9 Santiago (Bond) 8,408 8,299 8,690 6,203 224 202 285.4 Santiago (Blu Dia)5 5,372 5,245 5,240 285.4 Deep Basin Totals 24,031 22,228 26,161 14,758

Prado Dam6 9,782 19,663 25,000

NOTES: 1) "Avg W.S." is feet above Mean Sea Level. 2) Some values estimated where lack of instrumentation precludes calculation. 3) Warner system includes Foster-Huckleberry and Conrock basins. 4) Periodic discharge from YLWD's well #11 into Conrock Basin unaccounted for. 5) Storage in Blu Dia includes Smith Pit. Above elev 235, Santiago Pits respond as one basin. 6) Prado dam storage values provided by U.S. Army Corps of Engineers. "na" indicates data not available. FOREBAY PERCOLATION EFFICIENCY REPORT April-11

Actual Remarks RIVER SYSTEM 5,758 Average perc 96 cfs DESILTING SYSTEM 60 Estimated based on observations OFF-RIVER SYSTEM 0 See Five Coves WARNER SYSTEM 1 1,264 Includes Foster Huckleberry and Conrock basins OLIVE BASIN2 187 Inflow from Warner basin ANAHEIM LAKE1,894 Inflow from Warner basin MINI-ANA LAKE451 Inflow from Warner basin KRAEMER BASIN2,621 Inflow from Warner basin MILLER BASIN646 Inflow from GWR and Warner Basin LA JOLLA BASIN846 Inflow from Warner basin PLACENTIA BASIN3 0 Not in use RAYMOND BASIN3 5 No inflow this month FIVE COVES BASIN750 Incudes Off River and Lincoln Basin BURRIS BASIN982 Inflow from SAR RIVER VIEW BASIN245 Inflow from Burris Pit SANTIAGO BASINS5,489 Infow from Burris Pit SANTIAGO CREEK180 Inflow from Burris Pit TOTALS 21,378

TABLE 1 TABLE 2 AVAILABLE FLOWS TO RECHARGE SYSTEMS (AF) LOSSES FROM RECHARGE SYSTEM (AF) Imperial Headgates (OCWD) Estimated 21,854 Est'd SAR flow past Chapman Ave. 2,500 GWRS 2,958.02 OC-11 (MWD) 0 Est'd Santiago Cr. flow to SAR 0 OC-28 (MWD) 0.00 Est'd flows past Raymond Basin 0 OC-28a (MWD) 0 Est'd local Forebay inflow below Imperial4 10 Calc'd evap (inches) Estimated 4 Est'd local Santiago inflow (estimated) 65 Est'd evaporative losses5 167 Irvine lake releases (OC-13 MWD) 0 Villa Park Dam releases (estimated) 0 Precip at Warner Basin (inches) 0.03 Precip direct to open water surfaces5 1 TOTAL INFLOW 24,888 TOTAL LOSSES 2,667

TABLE 3 STORAGE CHANGES (AF) SUMMARY Facility Begin End Net Deep basins 8,684 9,490 806 TOTAL INFLOW (TABLE 1) 24,888 Santiago Pits 13,544 13,581 37 TOTAL LOSSES (TABLE 2) 2,667 River 0 STORAGE CHANGE 6 (TABLE 3) 843 Off-river 0 CALC'D PERCOLATION 21,378

Irvine Lake TOTAL 22,228 23,071 843 NOTES: 1) Warner system includes est monthly perc values for Foster-Huckleberry and Conrock basins. 2) No instrumentation in Olive Basin; perc estimated. 3) Placentia and Raymond are County of Orange RDMD flood control basins. 4) Carbon Diversion included. 5) Estimated Precipitation and Evaporation is based on 500 acres of open water surface. 6) Net "negative" storage is water volume moving from basins to underground recharge. PERCOLATION BASIN MONTHLY SUMMARY April-11 (values in acre-feet)

Facility Storage Storage Maximum Total Max Avg Avg W.S. 1 Start End Storage Perc Perc Perc Elev Desilting Ponds2,3 230 230 230 60 0 0 Fos-Huckleberry2,3 552 560 630 na na Conrock Basin3,4 932 951 1,060 na na Warner Basin 2,502 2,485 2,600 1,264 na na Little Warner 199 197 210 na na na Olive Pit2 0 37 183 187 16 22 200 Anaheim Lake 2,033 2,092 2,300 1,894 70 66 220.7 Mini-Anaheim Lk 0 5 21 451 24 8 na Miller Basin 294 90 340 646 48 40 207.4 Kraemer Basin 0 234 1,050 2,621 138 88 178.0 La Jolla Basin 4.78 7.21 846 36 12 201.0 Placentia Basin2 5 5 75 0 0 0 na Raymond Basin2 5 0 162 5 0 0 na Five Coves Basins 200 297 700 750 na na na Burris Pit 1,727 2,300 2,670 982 40 34 167.6 Santiago (Bond) 8,299 8,317 8,690 5,489 194 184 285.2 Santiago (Blu Dia)5 5,245 5,264 5,240 285.2 Deep Basin Totals 22,228 23,071 26,161 15,195

Prado Dam6 19,663 13,565 25,000

NOTES: 1) "Avg W.S." is feet above Mean Sea Level. 2) Some values estimated where lack of instrumentation precludes calculation. 3) Warner system includes Foster-Huckleberry and Conrock basins. 4) Periodic discharge from YLCWD's well #11 into Conrock Basin unaccounted for. 5) Storage in Blu Dia includes Smith Pit. Above elev 235, Santiago Pits respond as one basin. 6) Prado dam storage values provided by U.S. Army Corps of Engineers.

"na" indicates data not available. FOREBAY PERCOLATION EFFICIENCY REPORT May-11

Actual Remarks RIVER SYSTEM 5,785 Average perc 93 cfs DESILTING SYSTEM 60 Estimated based on observations OFF-RIVER SYSTEM 690 Used est of 12 cfs for days with flow WARNER SYSTEM 1 1,331 Includes Foster Huckleberry and Conrock basins OLIVE BASIN2 632 Inflow from Warner basin ANAHEIM LAKE1,123 Inflow from Warner basin MINI-ANA LAKE469 Inflow from Warner basin KRAEMER BASIN3,333 Inflow from Warner basin, Anaheim lake and OC-28 MILLER BASIN1,844 Inflow from GWR, Warner Basin and OC-28 LA JOLLA BASIN433 Inflow from Warner basin, Anaheim lake and OC-28 PLACENTIA BASIN3 0 Not in use RAYMOND BASIN3 237 Inflow from Warner basin, Anaheim lake and OC-28 FIVE COVES BASIN123 Based on estimate of 2 cfs from last drop test BURRIS BASIN779 Inflow from SAR RIVER VIEW BASIN95 Inflow from Burris Pit SANTIAGO BASINS5,108 Infow from Burris Pit SANTIAGO CREEK282 Inflow from Burris Pit TOTALS 22,324

TABLE 1 TABLE 2 AVAILABLE FLOWS TO RECHARGE SYSTEMS (AF) LOSSES FROM RECHARGE SYSTEM (AF) Imperial Headgates (OCWD) Estimated 15,020 Est'd SAR flow past Chapman Ave. 0 GWRS 3,289.54 OC-11 (MWD) 0 Est'd Santiago Cr. flow to SAR 0 OC-28 (MWD) 724.37 Est'd flows past Raymond Basin 0 OC-28a (MWD) 518.45 Est'd local Forebay inflow below Imperial4 10 Calc'd evap (inches) Estimated 5 Est'd local Santiago inflow (estimated) 65 Est'd evaporative losses5 208 Irvine lake releases (OC-13 MWD) 0 Villa Park Dam releases (estimated) 0 Precip at Warner Basin (inches) 0.57 Precip direct to open water surfaces5 24 TOTAL INFLOW 19,651 TOTAL LOSSES 208

TABLE 3 STORAGE CHANGES (AF) SUMMARY Facility Begin End Net Deep basins 9,490 7,178 -2,312 TOTAL INFLOW (TABLE 1) 19,651 Santiago Pits 13,581 13,012 -569 TOTAL LOSSES (TABLE 2) 208 River 0 STORAGE CHANGE 6 (TABLE 3) -2,881 Off-river 0 CALC'D PERCOLATION 22,324

Irvine Lake TOTAL 23,071 20,190 -2,881 NOTES: 1) Warner system includes est monthly perc values for Foster-Huckleberry and Conrock basins. 2) No instrumentation in Olive Basin; perc estimated. 3) Placentia and Raymond are County of Orange RDMD flood control basins. 4) Carbon Diversion included. 5) Estimated Precipitation and Evaporation is based on 500 acres of open water surface. 6) Net "negative" storage is water volume moving from basins to underground recharge. PERCOLATION BASIN MONTHLY SUMMARY May-11 (values in acre-feet)

Facility Storage Storage Maximum Total Max Avg Avg W.S. 1 Start End Storage Perc Perc Perc Elev Desilting Ponds2,3 230 230 230 60 0 0 Fos-Huckleberry2,3 560 500 630 na na Conrock Basin3,4 951 865 1,060 na na Warner Basin 2,485 2,464 2,600 1,331 na na Little Warner 197 194 210 na na na Olive Pit2 37 87 183 632 24 20 218.7 Anaheim Lake 2,092 0 2,300 1,123 60 36 210.0 Mini-Anaheim Lk 5 5 21 469 26 16 225.1 Miller Basin 90 311 340 1,844 76 60 214.7 Kraemer Basin 234 447 1,050 3,333 157 108 187.0 La Jolla Basin 7.21 2.10 433 40 0 200.0 Placentia Basin2 5 5 75 0 0 0 na Raymond Basin2 0 80 162 237 0 0 na Five Coves Basins 297 178 700 123 na na na Burris Pit 2,300 1,810 2,670 779 36 26 166.1 Santiago (Bond) 8,317 8,053 8,690 5,108 176 165 284.7 Santiago (Blu Dia)5 5,264 4,959 5,240 284.7 Deep Basin Totals 23,071 20,190 26,161 15,472

Prado Dam6 13,565 8,221 25,000

NOTES: 1) "Avg W.S." is feet above Mean Sea Level. 2) Some values estimated where lack of instrumentation precludes calculation. 3) Warner system includes Foster-Huckleberry and Conrock basins. 4) Periodic discharge from YLWD's well #11 into Conrock Basin unaccounted for. 5) Storage in Blu Dia includes Smith Pit. Above elev 235, Santiago Pits respond as one basin. 6) Prado dam storage values provided by U.S. Army Corps of Engineers.

"na" indicates data not available. FOREBAY PERCOLATION EFFICIENCY REPORT June-11

Actual Remarks RIVER SYSTEM 5,620 94 cfs average perc DESILTING SYSTEM 30 Estimated based on observations OFF-RIVER SYSTEM 714 Used est of 12 cfs for days with flow WARNER SYSTEM 1 1,211 Includes Foster Huckleberry and Conrock basins OLIVE BASIN2 376 Inflow from Warner basin ANAHEIM LAKE2,855 Inflow from Warner basin and OC-28 MINI-ANA LAKE365 Inflow from Warner basin and OC-28 KRAEMER BASIN6,509 Inflow from GWR, Anaheim lake and OC-28 MILLER BASIN1,403 Inflow Warner Basin and OC-28 LA JOLLA BASIN1,216 Inflow from Warner basin, Anaheim lake and OC-28 PLACENTIA BASIN3 354 Inflow to basin assumed as half of total to RAYMOND BASIN3 387 Placentia and Raymond basins (no flowmeters) FIVE COVES BASIN119 Based on estimate of 2 cfs from last drop test BURRIS BASIN938 Inflow from SAR RIVER VIEW BASIN367 Inflow from Burris Pit and Santiago SANTIAGO BASINS4,583 Infow from Burris Pit SANTIAGO CREEK268 Inflow from Burris Pit and Santiago TOTALS 27,314

TABLE 1 TABLE 2 AVAILABLE FLOWS TO RECHARGE SYSTEMS (AF) LOSSES FROM RECHARGE SYSTEM (AF) Imperial Headgates (OCWD) Estimated 16,800 Est'd SAR flow past Chapman Ave. 0 GWRS 3,483.05 OC-59 (MWD) 50 Est'd Santiago Cr. flow to SAR 0 OC-28 (MWD) 9,740.40 Est'd flows past Raymond Basin 0 OC-28a (MWD) 0.00 Est'd local Forebay inflow below Imperial4 0 Calc'd evap (inches) Estimated 5 Est'd local Santiago inflow (estimated) 65 Est'd evaporative losses5 208 Irvine lake releases (OC-13 MWD) 0 Villa Park Dam releases (estimated) 0 Precip at Warner Basin (inches) 0.05 Precip direct to open water surfaces5 2 TOTAL INFLOW 30,091 TOTAL LOSSES 208

TABLE 3 STORAGE CHANGES (AF) SUMMARY Facility Begin End Net Deep basins 7,178 9,675 2,497 TOTAL INFLOW (TABLE 1) 30,091 Santiago Pits 13,012 13,083 71 TOTAL LOSSES (TABLE 2) 208 River 0 STORAGE CHANGE 6 (TABLE 3) 2,568 Off-river 0 CALC'D PERCOLATION 27,314

Irvine Lake TOTAL 20,190 22,758 2,568 NOTES: 1) Warner system includes est monthly perc values for Foster-Huckleberry and Conrock basins. 2) No instrumentation in Olive Basin; perc estimated. 3) Placentia and Raymond are County of Orange RDMD flood control basins. 4) Carbon Diversion included. 5) Estimated Precipitation and Evaporation is based on 500 acres of open water surface. 6) Net "negative" storage is water volume moving from basins to underground recharge. PERCOLATION BASIN MONTHLY SUMMARY June-11 (values in acre-feet)

Facility Storage Storage Maximum Total Max Avg Avg W.S. 1 Start End Storage Perc Perc Perc Elev Desilting Ponds2,3 230 230 230 30 0 0 Fos-Huckleberry2,3 500 515 630 na na Conrock Basin3,4 865 884 1,060 na na Warner Basin 2,464 2,490 2,600 1,211 na na Little Warner 194 198 210 na na na Olive Pit2 87 90 183 376 18 12 220.2 Anaheim Lake 0 1,405 2,300 2,855 164 98 198.8 Mini-Anaheim Lk 5 15 21 365 24 12 224.5 Miller Basin 311 258 340 1,403 58 48 217.5 Kraemer Basin 447 984 1,050 6,509 240 218 210.8 La Jolla Basin 2.10 4.20 1,216 50 42 200.6 Placentia Basin2 5 70 75 354 0 0 na Raymond Basin2 80 112 162 387 0 0 na Five Coves Basins 178 178 700 119 na na na Burris Pit 1,810 2,242 2,670 938 44 32 167.8 Santiago (Bond) 8,053 8,086 8,690 4,583 180 154 282.3 Santiago (Blu Dia)5 4,959 4,997 5,240 Deep Basin Totals 20,190 22,758 26,161 20,345

Prado Dam6 8,221 0 25,000

NOTES: 1) "Avg W.S." is feet above Mean Sea Level. 2) Some values estimated where lack of instrumentation precludes calculation. 3) Warner system includes Foster-Huckleberry and Conrock basins. 4) Periodic discharge from YLWD's well #11 into Conrock Basin unaccounted for. 5) Storage in Blu Dia includes Smith Pit. Above elev 235, Santiago Pits respond as one basin. 6) Prado dam storage values provided by U.S. Army Corps of Engineers.

"na" indicates data not available.

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Orange County Water District P.O. Box 8300 Fountain Valley, CA 92728-8300 (714) 378-3200 (714) 378-3373 fax www.ocwd.com