Fort Jones, Calif. — Groundwater in the Scott Valley – how
it moves, how much there is and what happens to it – was the
topic of discussion Thursday night in Fort Jones as Dr.
Thomas Harter of the University of California, Davis
presented an update on the effort to better understand the
resource.
According to Harter, graduate student Ryan Hines performed a
large amount of the work required to build a model of
groundwater transport throughout the valley, which included
finding Department of Water Resources well data and study of
the different types of material through which groundwater
travels.
By overlaying a grid on the valley, Harter said, Hines was
able to then assign different levels of hydraulic
conductivity – the measure of how easily water moves through
a substance – to each grid, as well as well depths, level of
groundwater and other variables affecting water movement.
By combining precipitation input and water coming into the
valley from other sources with the various losses of water,
an estimate of the total groundwater balance can be made,
Harter said.
While groundwater is lost in large part due to agricultural
pumping and to the natural flow into the Scott River, the
preliminary results, Harter explained, did not show an
“emptying-out of the aquifers.”
“The conflict is about how much fuller the groundwater can
be to maintain stream flows,” Harter said.
The next step in the process, Harter stated, will be to
check the modeling results against observed data to see how
well the assumptions work, and to factor in the uncertainty
involved with modeling natural phenomena.
“We’re not done,” Harter said, adding that the first results
are a demonstration of how much is known and how much more
knowledge is needed in the valley.
District 5 Supervisor Marcia Armstrong asked a number of
questions after Harter’s presentation on what is the
intended use of the modeling results and the data gathered.
A representative from the North Coast Regional Water Quality
Control Board said one of the reasons for the effort is that
it will create “a tool for empowering people to make
decisions.”
Harter echoed the belief that using the modeling and the
associated data could act as a tool for the community,
ultimately telling Armstrong that he does not have control
over how the information will be used once it is available.
“It is not my role to judge opinions,” Harter said.
With the modeling only a part of the overall Scott Valley
Groundwater Study Plan, Harter said that the next steps
include finding data gaps, determining future modeling
scenarios and gaining a better understanding of how
groundwater and surface water interact.
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