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For
scientists, measuring the water in a
river or a lake is relatively
straightforward. It’s much more
complicated to figure out how much water
lies underground.
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After
years of research, a team of scientists
has finally mapped what remains of these
hidden waters across the United States,
and they’ve produced the most extensive
estimate of the country’s groundwater to
date.
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Researchers
at Princeton University and the
University of Arizona took data from
about 800,000 wells and applied a
machine-learning model to estimate the
depth of the water table nationwide.
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“Groundwater
is out of sight and out of mind for most
people,” said Reed Maxwell, a
hydrologist at Princeton and co-author
of the recent study
in the journal Nature. “Knowing how much
we have will be helpful in knowing how
to use it wisely.”
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They
incorporated data on the geology of
aquifers and estimated down to nearly
1,300 feet, far deeper than most wells.
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The
scientists say their detailed map
and data could help local
decision-makers address overpumping from
stressed aquifers, and help researchers
estimate how much water has been
depleted.
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California
has seriously depleted groundwater in
the San Joaquin, Salinas and Cuyama
valleys, Ventura County and other
places, with some of the fastest
rates of water decline in
the world.
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In
parts of the Central Valley, where large
farms draw heavily from wells, aquifer
levels have plummeted.
The U.S.
Geological Survey estimates
it has lost 128 million acre-feet,
comparable to the volume of Lake Tahoe,
since pumps started pulling it out in
the early 20th century.
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That
was as of 2019, and water levels have continued to
decline.
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(Yueling Ma et al. / Princeton
University)
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In
the desert Southwest, the groundwater is
largely considered “fossil water”
because it took millennia to accumulate.
So once it is pumped out, it’s in effect
gone for good.
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Even
depleting small amounts of water can be
a problem, said co-author Laura Condon,
a University of Arizona hydrologist. “We
see this in Arizona and in Southern
California too, where long before you
run out of water, you start disappearing
wetlands, disappearing small
tributaries.”
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The
total quantity of water underground is
still immense. The scientists found
nationwide there is roughly 250 billion
acre-feet, or 13 times the volume of the
Great Lakes.
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Data
compiled by lead author Yueling Ma show
the Colorado River watershed has about
as much groundwater as the volume of the
Great Lakes, while California has about
70% of that.
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Research
shows vast portions of
the world are losing
fresh water and getting
drier. Groundwater
depletion accounts for
two-thirds of the
continents’ water
losses, contributing to
rising oceans.
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Those
are vast quantities, but the researchers
said that definitely doesn’t mean there
is plenty of water to recklessly use up.
Declines in groundwater levels have in
recent years caused household wells to
sputter and run dry,
streams and wetlands to dry up,
and land to sink, damaging
canals and levees.
California’s database of dry wells shows
about 6,000 have run dry since 2013, but
in the last year, only 13 dry wells were
reported. So that problem has slowed
down for now. It could soon worsen
again.
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The
new map shows
groundwater varies widely across the
country. In some places, you have to
drill down 300 feet to reach it. In
others, it’s just a few feet below the
soil.
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The
map
can help scientists studying where
slow-flowing aquifers are feeding
nature, nourishing
streams and wetlands.
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Jay
Famiglietti, a hydrologist and professor
at Arizona State University who wasn’t
involved in the research, called the
researchers’ map and estimates a
“remarkable achievement for modeling and
understanding groundwater” in the United
States.
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The
scientists “convincingly show that it is
now possible to simulate groundwater
depths and availability at very high
resolutions,” he said, and they have
made their results “accessible and
useful for water managers across the
country.”
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He
said the research adds to satellite
measurements that scientists
now use to track shifts in water over
time. What the country still needs, he
said, is a “national-scale network of
deep groundwater wells” to track the
quantity and quality of water all the
way down to bedrock.
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More
water news
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Two
years ago, Gov. Gavin Newsom announced a
strategy to save declining salmon. Now,
as Rachel Becker reports for
CalMatters, members of the
Winnemem Wintu Tribe say the state is
ending its support for an effort to
reintroduce endangered winter-run
Chinook to waters upstream of Shasta
Lake reservoir, and they feel betrayed.
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The
Trump administration recently announced
it will spend $40 million to begin a
plan to raise the height of Shasta Dam,
which would expand California’s largest
reservoir. As Camille von Kaenel reported
for E&E News by Politico, dozens of
environmental, fishing and tribal groups
sent a letter
to Newsom urging him to oppose the Trump
administration’s renewed effort to raise
the dam.
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I
followed up to ask Newsom’s office about
the idea of raising Shasta Dam. “We
aren’t getting distracted by conceptual
projects, years from viability,” Newsom
spokesperson Tara Gallegos said.
Instead, she said the governor is
focusing on getting the planned Sites
Reservoir built northwest of
Sacramento, which “will benefit regions
throughout California and is much
farther along towards construction.”
Gallegos added that the state already is
“a significant investor in the project,
and the federal government should join
us in ensuring this project comes to
fruition.”
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In
the San Joaquin Valley, the
Delta-Mendota subbasin has become the
fourth farming area to avoid being
placed on groundwater probation by state
regulators. The State Water Resources
Control Board voted this week not to
impose enforcement measures on the area,
Monserrat Solis reported for
SJV Water.
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In
the Owens Valley, Los
Angeles siphons water
from Sierra streams and
also pumps groundwater
from wells. Native
tribes are calling for
the city to take less
water.
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More
climate and environment news
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The
Trump administration has a budget
proposal that calls for increasing
military spending while slashing funding
for clean energy and federal science
programs. My colleague Hayley Smith wrote about
the proposed cuts, which are
strongly opposed by Democrats and
environmental groups.
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A
wolf that captured national attention
when she ventured into L.A. County
earlier this year continues to make
history. As Lila Seidman reports
for The Times, it’s the first time a
wolf has ventured into Inyo County in
the Eastern Sierra in more than a
century.
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Imperial
County supervisors voted to combine
several parcels of land to clear the way
for construction of a massive data
center, which has faced opposition from
residents who worry about the complex’s
environmental footprint, Kori Suzuki reports for
KPBS.
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California’s
last remaining nuclear power plant has
received federal approval to run through
at least 2030. My L.A. Times colleague
Blanca Begert reports
that the federal Nuclear Regulatory
Commission has renewed Diablo Canyon
Power Plant’s license to operate.
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A
couple more things
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Los
Angeles Climate Week started April 8,
with a big lineup of community events
running through April 15. Here is the full
calendar of events, which
include a day of
activities along the L.A.
River and an interfaith
climate gathering.
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PBS
SoCal’s new season of its locally
produced environmental series Earth Focus
premieres April 22, Earth Day, at 7:30
p.m., with an episode focusing on how
L.A. stadiums are taking steps to be
more environmentally friendly.
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This
is the latest edition of Boiling
Point, a newsletter about climate
change and the environment in the
American West. Sign up here
to get it in your inbox.
And listen to our Boiling Point
podcast here.
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For
more water and climate news, follow
Ian James @ianjames.bsky.social
on Bluesky and @ByIanJames
on X.
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More
L.A. Times environmental stories
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