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5.18 Water Resources

State Water Project Deliveries to the Antelope Valley – East Kern County Water Agency
(AVEK)

The Project is located within the existing AVEK service area, and AVEK is the only SWP
contractor in the Antelope Valley that would provide imported water for Project use.
Exhibit 5.18-6, Project Site and Tejon Ranch Company Land Ownership within the AVEK
Service Area, depicts the Project site and TRC lands in the context of the AVEK service area.
AVEK is a wholesale supplier of SWP water to the Antelope Valley region; they have a service
area of nearly 2,400 square miles in northern Los Angeles and eastern Kern Counties and a
small portion of Ventura County. AVEK has a contract with the DWR to receive up to 144,844
acre-feet per year of SWP water. Based on the ELT delivery reliability scenario in the DCR,
the Agency’s average year supply would be 85,460 acre-feet (59 percent) of the SWP contract
amount. In 2015, the AVEK service area had a population of 359,500 Antelope Valley
residents (AVEK 2016).

Under the Antelope Valley Adjudication Judgment and Physical Solution, AVEK has an
overlying pre-rampdown production right of 4,000 acre-feet per year (afy) and an overlying
production right of 3,550 afy at the end of the 7-year production rampdown period. The
Judgment and Physical Solution also provides AVEK with the right to produce an amount of
imported water return flows in any year equal to 34 percent of agricultural imported water
use and 39 percent of municipal and industrial imported water use multiplied by the average
amount of imported water used by AVEK in the preceding 5-year period. The 2015 UWMP
conservatively assumes that AVEK’s annual supply of groundwater is 3,550 afy and does not
include return flows that also may be available to the Agency (AVEK 2016).

AVEK has developed groundwater banking programs to increase the reliability of the
Antelope Valley region’s water supplies by storing excess water available from the SWP
during wet periods and recovering these supplies for delivery to customers during dry and
high demand periods or in the event the SWP system is disrupted. AVEK’s Water Supply
Stabilization Project No. 2 (Westside Water Bank) started operations in 2010, and currently
includes approximately 400 acres of groundwater recharge basins and 9 groundwater
recovery wells. Up to 20 new wells may be constructed as a part of the Westside Water Bank
project. Five irrigation wells existing on the property at the time of development may also be
used in the program. AVEK meters the water delivery and recovery amounts for the banking
program and will not recover more than 90 percent of the amount recharged to account for
evapotranspiration, other losses during recharge and conveyance, and metering accuracy.
The Eastside Water Banking and Blending Project started operations in 2016 and includes
three 2-acre recharge basins and three groundwater wells. The project allows for recharge
of raw water that is later recovered and blended for delivery to the Eastside Water
Treatment Plant (AVEK 2015).

The maximum recharge and recovery volumes for the Westside Water Bank are estimated
to be approximately 36,000 afy. AVEK can also recover groundwater from the Eastside Water
Bank (5,700 afy total estimated capacity) and from 3 potable groundwater wells in the Bench
Ranch Well Field (total capacity of about 3,700 afy). The 2015 UWMP projects that AVEK will
recover up to 36,000 afy from groundwater banking facilities during single-dry and multiple-
dry years (AVEK 2016).

R:\Projects\PAS\CEN\000306\Draft EIR\5.18 Water Resources-051117.docx 5.18-29 Centennial Project
Draft EIR