Lower Pilarcitos Creek Groundwater Basin Study - Coastside ...

Introduction
This report summarizes a study of the technical and economic feasibility of a
proposed Lower Pilarcitos Creek groundwater project in Half Moon Bay, California.
This study is based on available data and focuses on three telescoping study
areas: the Pilarcitos Creek watershed, Lower Pilarcitos Creek groundwater basin,
and proposed Lower Pilarcitos wellfield.
Background and Purpose
Coastside County Water District (CCWD) is responsible for provision of water
supply to customers within its service area, including the City of Half Moon Bay and
several unincorporated coastal communities. Currently, CCWD provides water from
several sources, including the Pilarcitos Creek wellfield in Pilarcitos Canyon, City of San
Francisco sources (Pilarcitos Lake and Crystal Springs Reservoir), and the Denniston
project (surface water diversions and wells north of the City). Moderate demand for
additional water service connections exists in the service area, and in light of expected
increased costs for water from City of San Francisco system, CCWD is considering
supplemental water supply sources, including the Lower Pilarcitos Creek groundwater
basin.
The purpose of this study is threefold:
• To evaluate the safe or perennial yield of the Lower Pilarcitos Creek
groundwater basin,
• To assess the potential for production from the five existing test wells in the
basin, and
• To prepare a cost estimate to construct the infrastructure for groundwater
production.
In addition, if the project is deemed feasible, this study is intended to provide the basis
for subsequent environmental review and application for a coastal development permit.
Scope and Study Area
CCWD has explored the feasibility of a Lower Pilarcitos Creek groundwater
project through previous efforts, including evaluation of existing wells for possible CCWD
acquisition during the 1991 drought relief program and an exploratory drilling program in
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