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It's all connected: Study confirms groundwater pumping linked to river, stream depletion

SIERRA VISTA — “Arizona’s water myth is that people believe they can pump ground water without affecting surface water.”

That assessment by hydrologist T. Allen J. Gookin’s was made some years ago, as legal proceedings to determine the San Pedro River’s navigability as a waterway before the Arizona Navigable Stream Adjudication Commission.

For decades, the meandering river has been the subject of numerous studies and has been proclaimed by many scientists as probably, the most studied river in the Southwest.

A host of federal, state and local governments and agencies, along with environmental groups, have all come to the same basic conclusion in their analyzations over the past three decades — the root of the health of the river grows up from the aquifer.

Now, a new study by Laura E. Condon, University of Arizona Department of Hydrology and Atmospheric Sciences, and Reed M. Maxwell, Groundwater Modeling Center at the Colorado School of Mines, offers another substantiation of the connection.

The authors produced the report, “Simulating the sensitivity of evapotranspiration and stream flow to large-scale water depletion.”

“Groundwater pumping has caused marked aquifer storage declines over the past century,” according to the report. “In addition to threatening the viability of groundwater-dependent economic activities, storage losses reshape the hydrologic landscape, shifting groundwater surface water exchanges and surface water availability. A more comprehensive understanding of modern groundwater-depleted systems is needed as we strive for improved simulations and more efficient water resources management.”

Their study hinged on isolating impacts of “decreased groundwater storage on the hydrologic landscape and start to unravel the hydrologic differences between modern, depleted, groundwater systems and natural watersheds.” They produced a modeling simulation which shows the impact groundwater levels to land surface disturbances.

In their research, they found roughly 200 cubic miles of water was withdrawn from aquifers across the United States over the 20th century. Depending on a finite source with an infinite–use state of mind leads to groundwater losses. Combined with varying climate conditions, the problem is exacerbated.

“The long–term storage losses caused by a century of groundwater development can be viewed as a large–scale reshaping of the integrated hydrologic landscape. This will influence watershed response to both natural and human perturbations moving forward. This study seeks to isolate the impact of decreased groundwater storage on the hydrologic landscape and start to unravel the hydrologic differences between modern depleted groundwater systems and natural watersheds,” they say.

Hydrologist Laurel Lacher stated in a 2011 report, “In general, the simulations predict that in the absence of any major water use changes in the basin, much of the San Pedro and Babocomari rivers will cease to have perennial baseflow over the next century due to widespread impacts of projected ground water pumping.”

USGS hydrologist Bruce Gungle and other USGS researchers noted in a 2017 report, “It should be obvious that a watershed perennially in deficit will likely never see an increase in natural water discharge to the river. Even if groundwater pumping were to stop today and the groundwater budget balance was positive for decades to come, the effects of the pumping over the past century would eventually capture surface flow from the river.”

The study continues, “Even if pumping were immediately stopped the cone of depression would continue to propagate for decades or more. Without significant mitigation measures, it is likely too late already to prevent declining water levels from reaching the San Pedro Riparian National Conservation Area from Charleston to Tombstone.”

However, hydrologists have concurred and have cautioned continuous groundwater pumping from the aquifer will turn the San Pedro River’s perennial reaches to intermittent or ephemeral and will end up dry like the Santa Cruz River to the west.

Recharge efforts

For the San Pedro Basin Aquifer, the study becomes one more affirmation of the importance of groundwater to surface water. Numerous modeling and ground-based data all show the connectivity of the basin aquifer and the river and various ways to sustain them are being tried.

For instance, Sierra Vista set up the Environmental Operations Park which recharges Sierra Vista’s A–quality treated effluent. The project helped raise “groundwater levels in a critical area that is both supporting San Pedro River flows and protecting the river from municipal groundwater pumping centers. Through the park’s 11 recharge basins, an average of 2,000 acre–feet is recharged annually, plus another 700 acre-feet of incidental recharge occurs across its wetlands.”

Cochise County constructed its first water recharge project off State Highway 92 in Palominas in 2014. The $1.1 million, 280–acre project was constructed with a recharge goal of 98–acre feet annually. However, monitoring records from July 2015 to July 2018 indicate a total of only 82.1–acre feet has been recharged.

Cy Miller, of JE Fuller Hydrology and Geomorphology, provided an update of county data collected from a number of monitoring sites for the Cochise Conservation and Recharge Network (CCRN) to the Upper San Pedro Partnership during the June meeting.

“Groundwater levels generally declined over the monitoring period from 2014. Palominas recharge facility showed an increase (mound) in groundwater elevations following Hurricane Odile in September 2014 at monitoring wells near the facility, but followed regional declines thereafter. Additional continued monitoring is recommended to provide a record from which hydrologic modeling methods can be refined,” he added.

Though the report acknowledged CCRN annual monitoring records show less runoff than the models predicted, the historical period of record does show high flows in other locations in the Sierra Vista Subwatershed. So other stormwater projects could “take advantage of available water in the best predicted locations and downstream of the greatest magnitudes of runoff.”

Stormwater recharge facilities are dependent on precipitation which varies from year to year, he continued. “CCRN anticipates that recharge project benefits will be relevant over the long-term, regardless of annual local precipitation variability.”


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Move by ACC allows prepaid customers' power to be cut off during summer months

SIERRA VISTA — The Sulphur Springs Valley Electric Cooperative was among a group of Arizona power companies that won a victory of sorts when the Arizona Corporation Commission (ACC) on Wednesday afternoon exempted them from part of an emergency order prohibiting power companies in the state from disconnecting residential customers’ service between June 1 and Oct. 15.

The ACC’s ruling specifically affects SSVEC’s residential customers who use the prepaid option. It comes in response to SSVEC’s request for a waiver from the emergency order, which went into effect this year. SSVEC argued that the commission had already created the exemption when they first approved prepaid metering three years ago, because of several factors.

Among those are the facts that companies offering the prepaid option do not require a security deposit or a letter of credit from a previous utility, and prepaid customers agree to manage their service on a frequently used device, such as a smartphone, explained Jack Blair, SSVEC’s chief member services officer.

The emergency order was unanimously approved by the ACC in June, less than a week after it was learned that a 72-year-old Sun City West woman died in September after having her power disconnected on a 107-degree day.

SSVEC’s residential customers who are billed for their service — accounts secured by deposits — are not affected by the ruling and will continue to be protected from service being disconnected because of nonpayment until Oct. 15.

The exemptions granted this week — they were actually voted on a week ago, but officially signed Wednesday — to SSVEC and the half-dozen or so other Arizona power companies who offer prepaid service do not completely disregard the danger posed by harsh weather. Power companies “shall not disconnect (prepaid) customers on any day where the high temperature is expected to hit or exceed 95 degrees Fahrenheit,” SSVEC’s exemption order reads.

Blair said SSVEC — which had asked that 100 degrees be the benchmark temperature to preclude disconnection — is happy to abide by the ACC’s decision to lower the threshold to 95 degrees. Additionally, Blair noted, the electric cooperative will only disconnect service on days when the company’s offices are open and also open the following day, which allows customers to quickly have their service restored.

SSVEC has been messaging its prepay customers since the ACC initially voted on the exemptions last week, letting them know of the coming change, Blair said. He added that the company began disconnecting service for residential prepay accounts that were in arrears on Thursday.

“But we try to work with people all the time on (setting up payment plans or other payment options),” Blair said, who noted that prepay customers comprise less than half of their customer base. “Disconnecting someone is not something we like to do or want to do. So, we’re open to working with people all the time.”

Blair said that some service organizations, such as the Salvation Army and others who have programs to help people pay utility bills, had some reservations about the emergency order when it was adopted in June. While understanding the safety aspect of preventing companies from disconnecting service during the hot summer months of Arizona, there was fear that the order could enable a mindset that people don’t need to pay their bills. Then, come Oct. 15 when the order allows companies to resume disconnections, some customers could face colossal bills that they’re unable to pay, and are too big for service organizations to cover as well.

“A lot of these service groups who help people with their utility bills went in and said, ‘This is not a good thing, because you’re going to end up having people owe a lot more, and we can help people with $25 or $50 or $100, but we’re not going to be able to help thousands of people with hundreds of dollars,’” Blair said.

Blair encouraged power customers who are still protected from disconnection until Oct. 15 to do their best to stay current with their bill.

“The disconnect rules aren’t forever,” he noted. “It’s important that people don’t fall too far behind, because this isn’t a free ride and eventually these bills are all going to be due.”

Meanwhile, Wednesday’s waiver from the ACC allowing power companies to disconnect prepaid service customers’ electricity didn’t move the needle much for customers going in and out of SSVEC’s Sierra Vista offices at 311 E. Wilcox Drive. Many said the move won’t affect them at all.

“Where I’m from, if you don’t pay your bill, you get your power cut off,” said Erik Pierce. “Simple as that. Just pay your bills.”

Michelle Kniffen, though, said she thinks there should be yet another exception to the power companies’ new exception.

“My opinion about it is if it’s elderly people or people with children, they shouldn’t be allowed to cut the power off,” Kniffen said. “If you’re elderly or have young kids, you’re more at risk, so they shouldn’t be allowed to cut those people’s power off.”