Wednesday, January 26, 2022 The Nugget Newspaper, Sisters, Oregon
WATER: Region9s
geology plays
a big role
Continued from page 1
outside the city limits rely on
their own individual or shared
wells for their water. All wells
are accessing groundwater.
Groundwater vs. surface
water
Groundwater is the water
that collects or flows beneath
the earth9s surface, filling the
porous spaces in soil, sedi-
ment, and rocks. It originates
from rain and melting snow
and ice and is the source of
water for aquifers, springs,
and wells.
The water table is an
u n d e rg r o u n d b o u n d a r y
between the soil surface and
the area where groundwater
fully saturates spaces between
sediments and cracks in rocks.
The saturated zone is bounded
at the bottom by impenetrable
rock or sediment. The aquifer
from which the City of Sisters
draws its water is a basalt
aquifer.
Surface water is the water
that is available above ground
in the form of rivers, streams,
oceans, lakes, and wetlands.
Surface water is mainly col-
lected from precipitation.
However, in the Deschutes
River Basin, studies have
determined there is a hydrau-
lic connection (operated by
the pressure of water) between
groundwater and surface
water. Groundwater appropri-
ations (wells) have the poten-
tial for substantial interference
with surface water and could
measurably reduce waterway
flows. Likewise, low stream
flows could reduce the amount
of groundwater available to be
pumped from a well.
What is an aquifer?
Aquifers are often iden-
tified by the way they were
formed. Alluvial aquifers are
water-deposited (usually by
moving water), and glacial
drift aquifers are deposited by
the gradual movement of gla-
ciers. Large aquifer systems
may be composed of several
geologic formations, includ-
ing both alluvial and glacial
drift deposits.
Coarse sand and gravel,
transported and deposited by
rapidly moving water, turns
into permeable aquifer depos-
its when buried. They can
extend laterally from a few
feet to many miles and can be
paper thin to hundreds of feet
thick.
The Deschutes Basin aqui-
fer has been described as a
large bowl, with a deep end
near the Cascade Mountains
(and Sisters) becoming shal-
lower up to the northeast and
Madras. Much of the eastern
side of the Cascade Range
drains into this bowl, which is
lined by large areas of perme-
able volcanic rock. When the
large annual precipitation at
higher elevations collects on
that permeable rock, the result
is a substantial regional aqui-
fer system and a stream sys-
tem that is heavily dominated
by groundwater, with either
resulting springs when the
groundwater is high or lower
water levels when the ground-
water level is lower. The
headwaters of the Metolius
and Fall Rivers, as well as the
springs downriver that feed
the Metolius, are examples
of that groundwater being
released.
When it comes to water,
Sisters is ideally located.
Groundwater elevations are
highest near the Cascade
Mountains in the west and
Newberry Volcano in the
south and decrease to the
northeast and north toward the
confluence of the Deschutes
and Crooked Rivers. The City
only needs to drill down about
300-plus feet to reach copious
groundwater.
Surface water became the
source for irrigation by the
early farmers and ranchers in
Sisters Country and beyond.
A large network of open
canals carried water through-
out the area. Gradually, over
the years, a number of those
canals have been replaced by
wells and irrigation ponds. In
recent years, the
Basin to the south
irrigation districts
central down by
have been piping
Sunriver. Some
the remaining
scientists believe
canals to stop
that the fault
leakage into the
could be respon-
ground.
sible for disrupt-
For almost
ing an even flow
100 years, due
of groundwater
to those leaky
to the east from
canals, the entire
higher western
area had an artifi-
elevations.
cially high water
Long-term
table. With the
groundwater
piping, the water
level records in
table is returning
the central part
to its original nat-
of the Upper
ural level, which
Deschutes Basin
is leaving some
have shown that
shallow wells dry,
some areas are
intermittently or
experiencing per-
MODIFIED FROM LITE AND GANNETT, 2002
permanently.
Sisters lies at an advantageous spot over the region’s water table. sistent groundwa-
Increasing
ter level declines,
water demands
Some of the more recent particularly in an area extend-
The demands for water in modeling done in the Upper ing from the vicinity of
the region are coming from all Deschutes Basin, in coop- Bend, north toward Lake
corners 4 a rapidly increasing eration with the Oregon Billy Chinook, and northeast
regional population, agricul- Water Resources Department toward Redmond and Powell
ture, environmental projects, (OWRD), explores the influ- Butte. The Deschutes Basin
hydroelectric, businesses, and ence of well location and geo- Groundwater Mitigation
recreation. Additional appro- logic structure on stream cap- Program allows for limited,
priations for surface water ture by pumping wells. The additional groundwater devel-
have been closed. In a col- OWRD report states:
opment using mitigation to
laborative effort, a new water
<Wells were simulated offset the impacts to the State
bank project by the Deschutes at three locations within a Scenic Waterways and spe-
River Conservancy will offer 12-mile area close to known cific instream rights.
payments to Central Oregon groundwater discharge areas
Sister area wells going
Irrigation District patrons in and crossed by a regional dry
exchange for renting their fault zone. Simulations indi-
In the Sisters Country area,
water out to the North Unit cate that the magnitude and this past summer, there have
for a year. There are several timing of stream capture from been reports of wells going
collaborations working on pumping is largely controlled dry, and the need to either
possible solutions to a variety by the geographic location of lower the pump or drill an
of water-related issues but, the wells, but that faults can entirely new well. Some of
where water is involved, each have a large influence on the the reports came from proper-
possible solution can also have increase of pumping stresses.= ties on Harrington Loop, Gold
unintended consequences.
Sisters fault zone
Coach Road, and around the
Impact of climate cycles
In addition to the regional Cloverdale area, as well as
Additionally, the current flow pattern from higher Terrebonne and Redmond. It
climate cycle has the area in groundwater elevations near is important to remember that
a drought, so the amount of the mountains, groundwater most wells, depending on cir-
snow melt in the mountains levels in the central part of cumstances, have a lifespan
is currently reduced, leaving the Upper Deschutes Basin of 30-50 years and most well
less ground and surface water are several feet to several pumps typically last anywhere
to meet increasing demands. hundred feet below the sur- from eight to 15 years.
Glaciers are integral to the face of the land, indicating
In subsequent articles, we
Central Oregon ecosystems that stream reaches in the will explore one longtime
and economies, and they are central part of the basin are Sisters resident9s experience
disappearing, most likely due separated from the regional with wells, what to do if your
to regional climate change. A groundwater flow system by well runs dry, as well as water
new unnamed lake now sits an unsaturated zone, perhaps as it relates to growth and
on the flanks of North Sister along the Sisters Fault Zone development and the political
where Thayer Glacier used to which runs from the north- umbrella of more regulated
flow.
west of the Upper Deschutes uses, higher costs, etc.
FUN & GAMES
SUDOKU EASY PEASY!
MATH SQUARE
Place a number in the empty boxes in such
a way that each row across, each column
down, and each small nine-box square con-
tains all of the numbers from 1 to 9.
Use the numbers 1 through 16 to complete
the equations. Each number is used once.
Each row is a math equation. Each column is a
math equation. Remember that multiplication
and division are performed before addition
and subtraction.
WORD SEARCH PUZZLE
14