Page 135 - Yucaipa Sustainable Groundwater Management Agency - Yucaipa SGMA

SGMA Project Management and Development of a GSP

Client: BWD and County of San Diego
Dates: 2013–Present
Key Dudek Staff: Peter Quinlan, Trey Driscoll (Project Manager), Jill Weinberger, Steven Stuart, Daniel
Ritter, Hugh McManus, Dylan Duvergé, Kyle Harper
Reference: Geoff Poole, BWD General Manager, 760.767.5806, geoff@borregowd.org

Dudek is managing the development of
a GSP for the critically overdrafted
Borrego Valley Groundwater Basin for
the BWD and the County of San Diego.
Dudek has prepared cost estimates for
the GSP; technical analysis of the
existing BWD and County Demand Offset
Water Credit Policy; scientific and
jurisdictional analysis of the basin
boundaries to support application for a
Bulletin 118 BBM; water replacement
cost analysis; and analysis on managing
proportional groundwater production
cutbacks through a water market
approach. Dudek is also currently
building a custom data management
platform to support the Borrego GSP and
providing on-call grant application preparation services and support for various projects through
numerous chapters of Proposition 1 for the district.

Dudek has worked collaboratively with USGS in modifying the Borrego Valley Hydrologic Model, a
finite-difference groundwater flow numerical model developed by USGS using the MODFLOW-
OWHM code, to extend the simulation period from 2010 to 2016. Dudek updated the numerical
model by incorporating known and estimated pumping at wells in the basin up to the end of 2016.
The model was validated by simulating conditions from 2010 to 2016 and comparing the simulated
results to observed water level data collected from 2010 to 2016. Model validation is a measure of
the uncertainty in model predictions. Improvements in model accuracy may be made after
identifying the model parameters that result in the greatest uncertainty and implementing future
investigations and data collection to reduce the uncertainty. Dudek identified three conditions, or
parameters, that contributed most to uncertainty: estimated pumping in lieu of actual metered
pumping, aquifer storage, and recharge from infiltrating stream flow. Additional information on
pumping, storage and recharge will be collected over the next 5-year period to reduce uncertainty
and generate more accurate simulations.

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Yucaipa Sustainable Groundwater Management Agency - August 9, 2018 - Page 133 of 208