If the MPWSP is constructed as described in the FEIR for the North Marina Project, the slant wells would pump from the unconfined Dune Sand Aquifer. If groundwater is pumped from an unconfined aquifer and the modeling assumptions in the FEIR for the North Marina Project are accurate, there will be lowering of groundwater levels within an approximate 2-mile radius. Since seawater intrusion occurs in this area, this water developed through desalination is likely new water that is “surplus” to the current needs of other users in the Basin. Based on the information available, it is unlikely any injury would occur by the lowering of the groundwater levels in this region. Nevertheless, Cal-Am must show there is no injury and if the MPWSP reduces the amount of fresh water available to other legal users of water in the Basin or reduces the water quality so that users are no longer able to use the water for the same beneficial use, such impacts would need to be avoided or compensated for.
If the proposed slant wells are determined to be infeasible,
and the project is instead designed to extract groundwater with conventional pumping
wells, the potential impacts could be greater, but they would not necessarily result in
injury that could not be avoided or compensated through appropriate measures.
Impacts on other water users in the form of increased groundwater pumping costs could be
eliminated through financial compensation within a reasonable time frame from
when the costs are incurred. Impacts on the availability of fresh water could
be determined through modeling and any replacement of fresh water would have to be
returned in an area that is not already degraded by seawater intrusion. Impacts on
users in the form of decreased water quality could be compensated through the
replacement of water with similar quality to the pre-project conditions.
Modeling for the North Marina Project does not predict that
Basin users’ fresh water supplies would be affected if its wells pump from an
unconfined aquifer, which we assume to also be true for the MPWSP. If however, further
exploratory testing shows water is removed from a confined aquifer, water levels would
be lowered in a larger area and the effect on groundwater flow direction would be
greater. Although pumping from a confined condition affects a much larger area of the
Basin, the quantity of fresh water extracted from the aquifer would not necessarily be
greater because the capture zone for the extraction wells would be greatly influenced by
existing groundwater gradients. Additional studies are needed to determine
whether the revised MPWSP configuration could cause injury to other groundwater users
in the Basin that would require additional measures to avoid or compensate for that
injury.
Cal-Am could legally pump from the Basin by developing a new
water supply through desalination and showing the developed water is surplus to
the existing supply. If Cal- Am’s extractions are limited to water that currently serves
no beneficial use; for example, it is entirely derived from brackish or seawater
sources, and Cal-Am returns all incidental fresh water to the Basin in a method that avoids
injury to other users, it is likely the MPWSP could proceed without violating other
users’ groundwater rights. A no injury finding would have to be shown through monitoring,
modeling, compensation, project design or other means
A physical solution could be implemented to ensure all
rights are protected while maximizing the beneficial uses of the Basin’s waters. Such
an approach is consistent with the general policy in California Constitution article X
section 2, and case law provides guidance on solutions to address complex
groundwater issues where supply is constrained. The ongoing development of solutions tailored
to the specific conditions that apply to a given groundwater basin reflects the
understanding that California
waters are too valuable not to be utilized to the maximum extent
possible if beneficial uses and other legal users’ rights are maintained.
Recommendations states: Additional information is needed to
accurately determine MPWSP impacts on current and future Basin conditions
regardless of whether the extraction occurs from pumped or gravity wells.
First, specific information is needed on the depth of the wells and aquifer conditions.
Specifically, studies are needed to determine the extent of the Dune Sand Aquifer,
the water quality and quantity of the Dune Sand Aquifer, the extent and thickness
of the SVA and the extent of the 180-Foot Aquifer.
Second, the effects of the MPWSP on the Basin need to be
evaluated. Specifically, a series of test boring/wells would be needed to assess the
hydrogeologic conditions at the site. Aquifer testing is also needed to determine the
pumping effects on both the Dune Sand Aquifer and the underlying 180-Foot Aquifer.
Pre-project conditions should be identified prior to aquifer testing. Aquifer tests should
mimic proposed pumping rates.
Third, updated groundwater modeling will be needed to
evaluate future impacts from the MPWSP. Specifically, modeling scenarios will need to be run
to predict changes in groundwater levels, groundwater flow direction, and changes
in the extent and boundary of the seawater intrusion front. Additional studies
also will be necessary to determine how any extracted fresh water is replaced, whether
through re-injection wells, percolation basins, or through existing recharge programs.
It may also be necessary to survey the existing groundwater users in the affected area.
The studies will form the basis for a plan that avoids injury to other groundwater
users and protects beneficial uses in the Basin. To ensure that this modeling provides the
best assessment of the potential effects of the MPWSP, it is important that any new
information gathered during the initial phases of the groundwater investigation be
incorporated into the groundwater modeling studies as well as all available
information including current activities that could influence the groundwater quality in the Basin.
STATE WATER RESOURCES CONTROL BOARD
FINAL REVIEW OF CALIFORNIA AMERICAN WATER COMPANY’S
July 31, 2013
RELATED NEWS ARTICLE:
By JIM JOHNSON Herald Staff Writer, 08/05/2013
Excerpts Highlights:
Cal Am could proceed with its plans, the report said, if it
shows the desal water it produces is developed water, that its plans to return
any fresh water it pumps from the basin are effective and feasible, and that
the project won't irreparably harm other users.
The report outlines a series of studies needed to determine
the nature and extent of the basin's aquifers, the project's potential effect
on the basin, and updated groundwater modeling capable of evaluating future
impacts from the project.
As part of a settlement agreement announced last week, Cal
Am and the Salinas Valley Water Coalition agreed that their hydrologists,
technical teams and other designated experts would form a "technical work
group" to develop a written plan for evaluating the intake sites.
The primary purpose of the work plan is to reach a consensus on hydrogeologic studies, well tests, field work, modeling, monitoring and other data needed to evaluate to what extent Cal Am's desal plant would affect the Salinas Valley Groundwater Basin and the water supply available to legal users.
The primary purpose of the work plan is to reach a consensus on hydrogeologic studies, well tests, field work, modeling, monitoring and other data needed to evaluate to what extent Cal Am's desal plant would affect the Salinas Valley Groundwater Basin and the water supply available to legal users.
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