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USGS: Water gauge monitoring critical to see scope of issue
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| Jim Leenhouts, an associate director of U.S. Geological Survey projects, makes a presentation on "Are we running out of water?" at Southeast Arizona Ag Day in February in Willcox. (AINSLEE S. WITTIG/ARN) |
By Shar Porier/Wick Communicaions
BISBEE - Can the U.S. Geological Survey continue monitoring gauges and wells in the Upper San Pedro River watershed without the county's financial assistance?
The answer to that question, originally asked by Cochise County Board of Supervisor Richard Searle, is basically "no."
So said Jim Leenhouts, associate director of USGS projects, at a work session held last Tuesday afternoon.
The USGS receives around $30,000 annually from the federal government to study the San Pedro River and the aquifer under a law that protects the river and its endangered or rare species.
It also is the law that requires Fort Huachuca to reduce its water consumption to retain a flow of water in the river and sets a date of 2011 to reach a sustainable yield, which is the amount going out of the aquifer must be equal to the amount going in, as well as keeping the river flowing. The Upper San Pedro Partnership was formed to deal with these issues, Leenhouts said.
But it is not enough to continue gathering data and studying what is going on underground.
Searle's concern was born out of a desire to cut county costs somewhere, and the USGS was one of those costs that he thought may have been a good candidate to cut. Leenhouts gave an overview, at times very technical, as to just what the USGS does for the $50,000 the county gives the agency annually for hydrological studies of the aquifer that includes sites at the Babocamari River, Lewis Springs and the San Pedro River, among others.
The USGS monitors three gauges in the county - one at Charleston Road, one at the upper Babocamari and one at the lower Babocamari - as well as a number of wells throughout the county.
These sites provide valuable information as to the extent of the water supply in the aquifer and can show trends of depletion when enough data has been gathered to actually track such trends, he said.
"We need long periods of records in order to identify trends and to see what is happening with the flows," Leenhouts said. "We would love to include more wells. Old agricultural wells not in use are good candidates. And the public can offer to volunteer old wells not in use."
Data has only been in collection for a few years in some areas to more than 12 in others. And while the USGS can determine what has happened over a few short years, more data allows for better understanding of short-term and long-term trends. Different weather patterns, such as El Niņo, can affect rainfall amounts over the short term, for instance. So, in order to identify what is really going on in the aquifer, the longer the record of data, the better picture of the health of the aquifer, Leenhouts said.
The monitoring of six wells at varying depths in the Lewis Springs area gives an indication of the hydrological system.
"This information is critical to future determinations," he said.
The only wells now showing a decline in the water table are on Fort Huachuca and some monitoring wells in other spots around the county, Leenhouts added. Yet, in other areas, the aquifer appears to be fine.
One of the ways they can determine just how the aquifer is holding up is through isotope tests of the water. Rain water at higher elevations, say in the Huachuca Mountains, is lighter than rain that falls at lower elevations, he explained.
By running the water through a spectrometer, the different masses of oxygen or hydrogen can be evaluated, and then it is known where the water came from. Water from a higher elevation, for instance, would carry a lighter elemental form of oxygen.
The water that is currently in the aquifer of the Sierra Vista Subwatershed District is around 12,000 years old, Leenhouts said. It can take that long for the water to make it to the aquifer from the mountains, he said. Snow and rain are the two main sources of recharge water, and though the amounts of both have diminished slightly in recent times, it can reach a point where what goes in does not equal what is pumped out.
And there is no way to know for sure if that threshold has not already been realized, Leenhouts said. With just a decade of data, there is no way of knowing whether the relatively flat line of the current status is good or bad. "That's why we need to continue gathering the information and studying it," Leenhouts said.
There was no action taken at the work session. That will come in a regular meeting in the future.
Herald/Review reporter Shar Porier can be reached at 520-515-4692.
The answer to that question, originally asked by Cochise County Board of Supervisor Richard Searle, is basically "no."
So said Jim Leenhouts, associate director of USGS projects, at a work session held last Tuesday afternoon.
The USGS receives around $30,000 annually from the federal government to study the San Pedro River and the aquifer under a law that protects the river and its endangered or rare species.
It also is the law that requires Fort Huachuca to reduce its water consumption to retain a flow of water in the river and sets a date of 2011 to reach a sustainable yield, which is the amount going out of the aquifer must be equal to the amount going in, as well as keeping the river flowing. The Upper San Pedro Partnership was formed to deal with these issues, Leenhouts said.
But it is not enough to continue gathering data and studying what is going on underground.
Searle's concern was born out of a desire to cut county costs somewhere, and the USGS was one of those costs that he thought may have been a good candidate to cut. Leenhouts gave an overview, at times very technical, as to just what the USGS does for the $50,000 the county gives the agency annually for hydrological studies of the aquifer that includes sites at the Babocamari River, Lewis Springs and the San Pedro River, among others.
The USGS monitors three gauges in the county - one at Charleston Road, one at the upper Babocamari and one at the lower Babocamari - as well as a number of wells throughout the county.
These sites provide valuable information as to the extent of the water supply in the aquifer and can show trends of depletion when enough data has been gathered to actually track such trends, he said.
"We need long periods of records in order to identify trends and to see what is happening with the flows," Leenhouts said. "We would love to include more wells. Old agricultural wells not in use are good candidates. And the public can offer to volunteer old wells not in use."
Data has only been in collection for a few years in some areas to more than 12 in others. And while the USGS can determine what has happened over a few short years, more data allows for better understanding of short-term and long-term trends. Different weather patterns, such as El Niņo, can affect rainfall amounts over the short term, for instance. So, in order to identify what is really going on in the aquifer, the longer the record of data, the better picture of the health of the aquifer, Leenhouts said.
The monitoring of six wells at varying depths in the Lewis Springs area gives an indication of the hydrological system.
"This information is critical to future determinations," he said.
The only wells now showing a decline in the water table are on Fort Huachuca and some monitoring wells in other spots around the county, Leenhouts added. Yet, in other areas, the aquifer appears to be fine.
One of the ways they can determine just how the aquifer is holding up is through isotope tests of the water. Rain water at higher elevations, say in the Huachuca Mountains, is lighter than rain that falls at lower elevations, he explained.
By running the water through a spectrometer, the different masses of oxygen or hydrogen can be evaluated, and then it is known where the water came from. Water from a higher elevation, for instance, would carry a lighter elemental form of oxygen.
The water that is currently in the aquifer of the Sierra Vista Subwatershed District is around 12,000 years old, Leenhouts said. It can take that long for the water to make it to the aquifer from the mountains, he said. Snow and rain are the two main sources of recharge water, and though the amounts of both have diminished slightly in recent times, it can reach a point where what goes in does not equal what is pumped out.
And there is no way to know for sure if that threshold has not already been realized, Leenhouts said. With just a decade of data, there is no way of knowing whether the relatively flat line of the current status is good or bad. "That's why we need to continue gathering the information and studying it," Leenhouts said.
There was no action taken at the work session. That will come in a regular meeting in the future.
Herald/Review reporter Shar Porier can be reached at 520-515-4692.
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