Ridin' Point, by Marcia Armstrong,
Siskiyou County Supervisor District 5, 11/2/07
has jurisdiction over groundwater use within the county. In
its water quality action plan for temperature pollution, the
North Coast Regional Water Quality Control Board (NCRWQCB)
County create a plan to “study the
connection between groundwater use on surface flow and
beneficial uses, and the impacts of groundwater levels on
the health of riparian vegetation in the watershed.” In
cooperation with the Scott River Watershed Council water
committee and the NCRWQCB, a grant was received to contract
with Thomas Harter, Ph.D. of University of
Extension Dept. of Land and Water Management. Harter was
given the study goals and series of “hypothesis,” (suggested
explanations for an observed state that can be
scientifically tested to see if they are true.) He has
designed a plan for a study using a series of scientific
methods to test the hypothesis and better understand the
relationship of groundwater use to surface water in
Participation in the
implementation of the study will be voluntary for the
landowner. I have publicly stated that “the train will not
leave the station until the landowners are on board.” That
means that the study will not get off the ground unless it
has the participation necessary to get the data needed. This
will involve outreach and education so that landowners
understand the study and its implications. If the study is
unsuccessful, NCRWQCB has stated that the State Water
Resources Control Board may decide to conduct a study.
Without voluntary landowner cooperation, it is unknown what
form this will take.
At a recent community meeting, Dr.
Harter talked about groundwater. He used the example of a
plugged flower pot, first filled with dirt, then with water.
The water fills the pores between the dirt. The moist top of
the dirt is the “vadose zone.” The saturated area at the
bottom of the pot is the “aquifer.” The top of the aquifer
is the “water table.” If the soil is clay or silt, there are
fewer pores to fill.
The direction water drains depends
on water pressure. High pressure or water elevation level
generally drains to low. The rate it drains depends upon how
porous the soil is. Drainage is fast through sand and slow
through clay. A stream gains water is the stream water level
is lower than the aquifer. It loses water if the stream is
higher than the aquifer.
River seems to be a gaining stream.
River flows can be influenced by
storm events. Depending on how long the precipitation takes
to get to the river, storm events can cause the flow to
increase to high stage and then decrease. “Base flow” is the
flow established from the steady discharge of groundwater
into the stream. The stream is connected with the
groundwater immediately beneath the stream in what is called
the “hyporheic zone.” The coarse streambed material allows
the intermixing of the waters. There is flow in the rivers
in summer only if the groundwater levels are higher than the
river levels are.
River groundwater study plan will try
to identify the areas where groundwater is upwelling into
the stream. It hopes also to determine if changes in water
management practices, can change the temperature in the
streams. According to Dr. Harter, the average annual
discharge in the Scott
Valley watershed is 615,000 acre feet
of water. This is more than the groundwater basin can hold
(400,000 acre ft. – U.S. Geological Survey.) It is
interesting to note that the Department of Water Resources
has estimated that agriculture uses only 70-90,000 acre ft.