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NorthLake Specific Plan
Draft Supplemental EIR

ranged from <5.0 μg/L to 340.0 μg/L and exceeded the chronic CTR criterion twice (Geosyntec
2015).

Water Supply Source and Quality

According to the WQTR, the Project’s water supply would be provided by the Newhall County
Water District (NCWD), a retail purveyor for the Castaic Lake Water Agency (CLWA). CLWA
receives and treats surface water from the State Water Project (SWP) and other imported
sources. The SWP consists of facilities operated by the DWR to transmit water to SWP
contractors for agricultural or urban supply uses. CLWA operates two water treatment plants, the
Earl Schmidt Filtration Plant in Castaic and the Rio Vista Water Treatment Plant in Saugus. The
Santa Clarita Valley’s four water retailers (Santa Clarita Water Division (SCWD), Los Angeles
County Waterworks District #36, NCWD, and Valencia Water Company (VWC) distribute the
treated imported water along with groundwater from the Alluvial Aquifer and the Saugus
Formation. The NCWD supplies water to its customers in an approximately 34-square mile area
in portions of the City of Santa Clarita and unincorporated portions of Los Angeles County
(Newhall, Canyon Country (Pinetree), Saugus (Tesoro), and Castaic (the Project location)
(Geosyntec 2015).

Existing water quality conditions for urban water uses in the CLWA service area are documented
in the Santa Clarita Valley Water Quality Reports (or Consumer Confidence Report [CCR]). An
st
annual Water Quality Report is provided prior to July 1 to all Santa Clarita Valley residents who
receive water from one of the four local retail water purveyors in the CLWA service area. There
is detailed information in that report about the results of quality testing of the groundwater and
treated SWP water supplied to the residents of the Santa Clarita Valley (Geosyntec 2015).

Perchlorate

As stated in the WQTR, the 2010 Santa Clarita Valley Urban Water Management Plan (UWMP)
discusses water quality constituents, both naturally occurring and man-made, in source waters.
The following sections summarize this information for a constituent of concern in groundwater,
perchlorate.

Perchlorate, a chemical used in making rocket and ammunitions propellants, has been a
groundwater quality constituent of concern in the Santa Clarita Valley since 1997 when it was
originally detected in four wells operated by the CLWA purveyors in the eastern part of the Saugus
Formation, near the former Whittaker-Bermite facility (CLWA, 2011). In late 2002, the contaminant
was detected in a fifth well, an Alluvial well (SCWD’s Stadium Well) also located near the former
Whittaker-Bermite site, which was immediately taken out of service. Perchlorate was detected
again in early 2005 in a second Alluvial well (VWC’s Well Q2) near the former Whittaker-Bermite
site, and in 2006 in very low concentrations (below the detection limit for reporting) in a Saugus
well (NCWD’s NC-13) near one of the originally impacted wells. The maximum contaminant level
(MCL) of six micrograms per liter (μg/L) was adopted by the California Department of Public
Health (DPH) in 2007 (Geosyntec 2015).

In August 2010, perchlorate was detected in VWC’s Saugus Well 201 (CLWA, 2011).
Confirmation sampling in the months that followed confirmed the detection of perchlorate at
concentrations that ranged from 5.7 to 12 μg/L. VWC removed Well 201 from service when
perchlorate was first detected (Geosyntec 2015).

To date, perchlorate has been detected in a total of eight wells, in both the Saugus Formation and
the Alluvium. Two of these wells (SCWD Saugus 1 and Saugus 2) have been returned to service
with DPH approval, utilizing approved perchlorate treatment. Two wells (VWC Well 157 and

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