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Projects and Programs
groundwater quality if allowed to percolate at local sites. More stormwater could be saved
by utilizing Best Management Practices (BMPs), e.g., bioswales, infiltration basins, and
porous pavements. Much of the WAS is focused on evaluating the technical feasibility of
this project and the potential impacts on groundwater quality. Other aspects of the WAS
include modeling to estimate the amount of water that can be percolated in the local
watershed and the economic value of this additional source of water. In 2009, the Elmer
Avenue neighborhood BMP demonstration project was constructed to evaluate the
effectiveness and potential of a large-scale project. Extensive monitoring of the BMP
demonstration project is planned for the coming years to assess the effectiveness of the
BMPs in water capture and maintaining or improving groundwater quality.
Stormwater Recharge Feasibility Study, which began mid-2011 and projected to finish in
May 2012, investigates regional and distributed alternatives to capture more stormwater for
groundwater recharge. To identify catchments or parcels with greatest potential to provide
additional groundwater recharge and reduce pollutant loading of surface water bodies (by
capturing and diverting stormwater, which otherwise would have discharged to rivers, creeks,
or the ocean), an in-depth, regional assessment was conducted using spatial analysis and
locally developed models, including the Structural Best management practices Prioritization
and Analysis Tool (SBPAT), the Groundwater Augmentation Model (GWAM), and the
WRD/U.S. Geological Survey (USGS) MODular three-dimensional finite-difference groundwater
FLOW model (MODFLOW). The assessment considered a suite of factors important
to siting groundwater recharge projects (e.g. surface flows, soil conditions, depth to water,
and subsurface geologic conditions, preexisting contamination, and permanent dewatering
activities) as well as local water quality objectives. Preliminary results have identified that
approximately 10% of the 270,000 acres within the WRD service area can be considered
high priority sites for local and regional stormwater recharge where expected water supply
benefits range from 8,000 to 13,000 acre-feet per year. A single 100 acre catchment was
selected and concept designs for a catchment-wide pilot stormwater capture and recharge
effort are under development and will be completed in spring 2012. Results from the
analyses and pilot project are scalable to inform future decisions about widespread
implementation of distributed and regional stormwater capture projects.
In 2011, as a member of the Southern California Water Committee (SCWC), the District
played a key role in the development of a whitepaper (released January 2012) on stormwater
capture opportunities throughout the coastal plain of Southern California. The paper is the
product of SCWC’s Stormwater Task Force, which was formed one year ago for the purpose
of collaborating regionally (Ventura, LA, Orange, San Bernardino, Riverside and San Diego
Counties representing approximately 20 million residents) on capturing more stormwater as a
water supply augmentation strategy within the coastal plain of Southern California. Towards
this effort, WRD collaborated with county flood control districts, water districts, other
groundwater management agencies, cities, builders, public interest groups and other
community leaders, who are all part of the SCWC Stormwater Task Force. This white paper
examined a number of relevant topics including: (1) existing statewide policies and goals and
regional plans related to integrated stormwater management; (2) trends, structure, and
requirements of municipal separate storm sewer systems (MS4) permits as they pertain to
both opportunities and constraints to maximizing stormwater capture for water supply
WRD Engineering Survey and Report, 2012 V-6