Page 154 - Yucaipa Sustainable Groundwater Management Agency - Yucaipa SGMA

satisfy this requirement, we propose to re‐scale and augment the five geologic sections generated in the
2016 USGS report, “Geologic Structure of the Yucaipa Area inferred from Gravity Survey Data” with well
construction, lithologic, and water level information to the cross sections. The cross sections will provide
basin‐wide coverage both parallel and perpendicular to regional groundwater flow directions.
Evaluate Current and Historical Groundwater Conditions. We will evaluate current and historical
groundwater level and water quality conditions. Historical changes in groundwater occurrence and flow
direction will be illustrated through (1) Basin‐wide groundwater elevation contour and groundwater
level change maps under current conditions (Water Year 2017‐18) and for selected historical high and
low water level periods, and (2) groundwater level change maps for time periods between high and low
water levels. Review of selected basin wells indicates historical high groundwater level conditions
occurred in the 1980s and 1999, while historical low water levels occurred more recently between 2007
and 2009.
Additionally, we will develop a figure showing water level hydrographs for key wells across the Basin.
Wells in close proximity with different screen interval depths may be grouped on one hydrograph to
illustrate vertical gradients between aquifers. We will also develop a current depth to water map to
illustrate the available vadose zone storage capacity across the Basin; this will support evaluations of
future projects (Task 4) and help identify any areas where groundwater dependent ecosystems (GDEs)
may exist, augmenting DWR‐provided information on vegetation and wetlands.

Groundwater in the Basin is a calcium‐bicarbonate type (similar to local surface water) and generally is
very good quality with most constituents meeting drinking water standards. For this task, we will work
with Valley District staff to identify and map current concentrations of target constituents of concern
across the Basin. We will also identify and map any existing contaminant plumes in the Basin that may
be affected by GSP management activities.
Evaluate Water Budget and Sustainable Yield. We will review previous evaluations of water budget
components and the Basin’s sustainable yield. We will document water budget estimates from
completed studies and extract historical water budgets from the USGS Model. Differences in water
budget components will be noted, including those that may be attributable to slight differences in
delineated basin boundaries.
Define Management Areas. SGMA allows the YGSA to define one or more management areas to facilitate
local management and implementation of the GSP. The Basin has been divided historically into eight
subbasins to account for apparent barrier effects of geologic faults. We recommend starting with a
conceptual ‘clean slate’ and anticipate discussing how the GSP will benefit from identifying more than
one management area while minimizing the need to establish multiple sets of sustainability goals and
criteria. This will be discussed through the public process between the YGSA and stakeholders, per GSP
Regulation § 354.20. Working with YGSA, we will examine management strategies and impacts for
treating the Basin under multiple management areas.

Task 3 – Establish Sustainability Goals and Management Criteria
The establishment of sustainable management criteria begins with the definition of a sustainability goal.
In order to determine if groundwater conditions meet that goal, an evaluation of undesirable results is
required. We will build on the hydrogeologic conceptual model, groundwater conditions, and water
budgets developed in Task 2 to identify and evaluate Sustainable Management Criteria for the YGSA, as

Proposal – SBVMWD Groundwater TODD GROUNDWATER
Sustainability Plan for the Yucaipa Basin Area 5 June 2018
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