Wednesday, July 23, 2014

Groundwater depletion sinks portions of Cedar Valley

By Amy Joi O'Donoghue, Deseret News

Published: Mon, March 31 2:53 p.m. MDT

 Too much groundwater pumping in Iron County's Cedar Valley is causing the land to sink and crack with the subsidence creating significant \

Too much groundwater pumping in Iron County's Cedar Valley is causing the land to sink and crack with the subsidence creating significant "fissures" in an urbanized area of Utah for the first time.

(Utah Geological Survey)

SALT LAKE CITY — Over-pumping of groundwater from a deep aquifer in Cedar Valley for the past three decades has caused the ground to sink and crack, inflicting damage on a would-be subdivision and putting future development at risk.

The mining of the aquifer — taking more water out than can be replenished — has already led to a moratorium on new allocations of water by the state engineer and may ultimately lead to harsher measures for existing water users.

"There's no way to make the ground go back up," said Boyd Clayton, Utah's assistant state engineer over water rights. "The limits would depend on how much worse it gets."

A just-released report from the Utah Geological Survey shows the ground has been sinking in some areas around Cedar City for decades. The 116-page report said the pumping has lowered the water table in the Cedar Valley aquifer by as much as 114 feet since 1939.

"They don't have a lot of water. It is a deep aquifer system that has a limited recharge, and they are using as much or more water than is being recharged into the system," Clayton said.

Tyler Knudsen, project geologist with the survey, said clay sediments and fine-grained silts over time become compacted due to water withdrawals, causing the land to sink.

The subsidence has caused a total of more than 8 miles of earth fissures to form in a 100-square-mile area of the valley. The damage was first noticed in May 2009 in a partially developed subdivision.

"Enoch City reported what they thought was an active fault disrupting the pavement, sidewalks, and curbs and gutter in a rather large subdivision," he said. "The fissure ran through the middle of several lots."

Knudsen added that the discovery marks the first time in Utah that an urbanized area has been impacted by ground subsidence and fissures — which have been responsible for tens of millions of dollars in damage in places such as North Las Vegas, Nev., California, and Texas.

The report, compiled with the support of the Central Iron County Water Conservancy District, noted that an annual average of 600 acre-feet of water has been pumped from the Cedar Valley since 1964.

Agricultural withdrawals make up the vast majority of that water use, though that has changed somewhat over time — from 96 percent in 1964 to 74 percent in 2008.

The report suggests possible aquifer management options to bring average annual groundwater discharge and recharge into balance to stop more damage from playing out.

Other areas that have had the problems — such as North Las Vegas and Murrieta, Calif. — require fissures and subsidence to be part of the consideration for any new development.

Enoch city manager Rob Dotson said the same type of restrictions will be in effect should there be any interest in developing impacted areas.

"They will have to come to us with a plan that works," Dotson said.

Email: amyjoi@deseretnews.com, Twitter: amyjoi16

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1. Red Smith
American Fork, UT,
March 31, 2014

Who is liable for the damages caused by the over pumping caused by the State Engineer authorizing too many water permits in Cedar Valley?

The San Joaquin Valley dropped 34 feet in elevation due to over pumping on farm ground.

Gray water recharge in Cedar Valley may help.

2. My2Cents
Taylorsville, UT,
April 1, 2014

I have wondered about this happening in Utah and many desert areas where aquifers have become abused and overused. It could even contribute to drought conditions in Utah and western states because ground water levels also affect humidity levels above the ground and there have never been any statistics or monitoring levels of atmospheric humidity. Ground evaporation does contribute to climatic changes and what some mistake as global warning rather than humidity depletion of aquifers.

This giant sink hole is in a remote area of the state and its cause for caution and to limit development in the more urban areas of the state in northern Utah. The west side of the valley lake Bonneville beach front property has already been impacted by mud slides and sinking homes and why the USGS had zoned the west area of the valley as not fit to develop for homes and business back in the 1930-1940's and our Utah government leaders have chosen to ignore the USGS warning.

These sink holes take time to reveal themselves and if oil fracking is developed in Utah then it may put Utah lower by hundreds of feet and ghost towns for tourist to visit.

3. Happy Valley Heretic
Orem, UT,
April 1, 2014

Some of these aquifers are left over from the last Ice age and lake bonneville. They haven't been being recharged with enough spring run off to compensate for what we're drawing out for probably 50 years, and in the last 20 (as My2Cents pointed out) our "leaders" a bunch of developers have ignored the USGS and built where ever they could snatch the land cheap.

4. not here
COLORADO SPRINGS, CO,
April 1, 2014

@ My2Cents:

Can and will you please share where your getting your information on Fracking. And it seems that you have no idea what your talking about, because there has been Fracking going on in Utah since they figured out that's what it took to break down formations in order to get gas and oil to flow. And if Fracking was/is going to cause sink holes then Eastern Utah is in for one heck of a shock because they have been Fracking those wells for decades. Oh look no cracks from Fracks. Oh and you will have bigger and better sink holes after they quit mining coal, and all of there shafts start to cave in but that's just common knowledge.

5. CylonesRus
sunamn, IN,
April 1, 2014

What would have happened if the MX missiles were staged in Utah 30+ years ago? That is what Orrin Hatch pushed for. That is when the good people should have got wise about Hatch.