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SIERRA VISTA - Scientists have a new problem to study concerning the San Pedro River, according to a U.S. Bureau of Land Management official.
The problem: to present information to policy makers to ensure water does not stop flowing past the waterway's Charleston gauge in the future.
When water was not recorded going by the gauge for the first time since a measuring device was put in the area more than 70 years ago, the Upper San Pedro Partnership's Technical Committee geared up to look at the causes, said Bill Childress, BLM's manager of the San Pedro Riparian National Conservation Area.
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On July 5 and for a few days following, no water was measured going by the gauge during daylight hours. Some water passed the device at night. From July 9-16, no water was measured during the day or night, Childress said.
Some environmental critics of growth in the Sierra Vista Subwatershed of the San Pedro River say unbridled development is the cause for the first-ever lack of water flowing pass the Charleston gauge.
However, Childress and others are not jumping on that bandwagon yet.
Drought, excessive heat and a late start of the summer rainy season may have been contributing factors, he said.
Over the past few years, the flow past the gauge has gone down and there are more wells being drilled to support growth, Childress said.
But, he said, "To me there is a variety of reasons that may have caused the problem."
The partnership has a number of scientists and technical personnel who can look at the reasons why the river dried up this year, Childress said. Those people also will need to come up with possible causes and recommended solutions for the partnership's policy makers.
It's not easy to claim one thing caused the problem when other issues combined to create the problem, he said.
"We have to look at it from a scientific base. That's what science is all about," Childress said.
The Partnership's Technical Committee will be meeting on Aug. 17 to discuss the issue.
Saying there are "tons of information already available," Childress said more data may have to be obtained before the committee can make a conclusion to present to all the partnership's members.
Without scientific conclusions, the group's policy makers, which include Sierra Vista and Cochise County elected officials and himself, cannot make logical decisions, Childress said.
Close prediction
A former county hydrologist Rick Koehler predicted that the Charleston gauge would go dry in 2006. Childress said he was a year off.
Koehler, who was hired by the county in July 1997, advised many times that growth and Mother Nature caused decreasing flows in the river. In 1999, Koehler noted that monsoon flows lessened and the summer rains were starting later.
With a delay in the summer monsoon, more water from the area's water table is used, especially by vegetation along the river, Koehler once said.
In 2000, he said the lessening of the water flow passed the Charleston gauge "doesn't appear to be a problem - yet."
In a Jan. 11, 2000, article in the Sierra Vista Herald/Bisbee Daily Review, Koehler said groundwater pumping is part of the river's problem.
Koehler now works for a federal agency in Colorado and could not be reached for additional comment.
Biological Diversity Center Board Chairman Dr. Robin Silver immediately jumped on the first report of the river drying up at the Charleston gauge.
On July 9, he sent out a news release stating "excessive deficit groundwater pumping on the Fort Huachuca/Sierra Vista (area) is now directly affecting (the) an Pedro River base flow."
According to figures from The Nature Conservancy, water flow that passed the gauge in six Junes - 1999 to 2004 - was normally less than 2 cubic feet per second, except for 2001 when it was slightly more than 3 cfs. A cfs equals 71/2 gallons of water going past a specific point in a second.
Reason for concern
U.S. Geological Survey hydrologist Don Pool said the lack of flow past the Charleston gauge is a major concern.
But Pool, too, said it is too early to place blame on a specific cause. He said that what happened at the Charleston gauge may not be indicative of what is going along the entire waterway in the San Pedro Riparian National Conservation Area.
People who want growth stopped because storm water in the Huachuca Mountains does not make it to the river fail to understand that the water from rains in those mountains soaks into the ground and then flows underground in a northeast direction, not east to the river.
There is a cone of depression, but it impacts the Babocomari River, a tributary to the San Pedro River, Pool said. A cone of depression is lowering the water's table surface in the vicinity of a pumping well, which causes water not to travel beyond the immediate area.
Two gauges along the Babocomari River also went dry in July, as did a number of similar devices in areas in southern Arizona, he said. And Pool noted that there is little development in some areas where gauges came up dry, such as in Lochiel in Santa Cruz County.
"I don't really know if the problem is man induced or not," he said.
There is no denying that in the past water flow at the Charleston gauge was more than has been measured in the past six years, Pool said. According to a USGS Web site, the 92-year average flow of water on July 30 is about 90 cfs.
On Saturday, it was slightly more than 6 cfs at 11 a.m.
The amount of water flowing past the Palominas gauge a few miles south of the Charleston device measured 3,500 cfs at 9 a.m. Saturday.
Between the two gauges is a stretch of the river where beavers have put up dams. Pool said that has to be looked at to see if it is reducing flow to the north.
Wells near the river also have an impact on the waterway's flow, he said.
"We know water levels are down in the river and some wells," Pool said. "A well close to the river has had a 2 foot (total) decline in the past 10 years."
The partnership is working on solutions, but the county has to do more to enhance its recharge capabilities, the USGS hydrologist said. And, he said, everyone has to practice more conservation.
John Glueck, a National Weather Service meteorologist, said the weather has been a major player in the past few years, causing stream flow to lessen.
The area near the river is in a moderate drought condition. Even with the recent rains, the area may have to go up to a severe drought condition, he said.
How long the drought, which officially started in 1998, will last is unknown because there have been more la Niñas instead of the wetter el Niños, he said. El Niños form in the Pacific and bring better rains to the southwest United States.
Watching the river
Every year The Nature Conservancy organizes a river walk, measuring where there is water in the stream.
Holly Richter, a member of the partnership's Technical Committee and The Nature Conservancy's Upper San Pedro program manager, said a reach of the river has to have at least 30-foot-long stretch of water to be considered a wet area.
Like others involved in the partnership, a consortium of federal, state and local agencies and private groups established to find solutions to ensure the San Pedro keeps flowing, Richter said what is happening in the waterway is a combination of problems.
"To be fair, we (the partnership) have done a lot, but not enough yet," she said.
Richter said the scientist in her wants to find out how the river works and what can be done to make sure it doesn't die.
But the clock is ticking for the partnership to have an answer ready to let Congress know that the organization has a solution to the area's water deficit, she said.
The river having dried up at the Charleston gauge for the first time will make it more difficult, Richter said.
"We have to have sustainable yield by 2011 and 2011 is right around the corner. It's a short period of time," she said.
For Childress, who is directed to keep the federally protected river alive, the partnership's Technical Committee has to come up with the best science possible, "and then the policy makers will have to make political decisions."
HERALD/REVIEW senior reporter Bill Hess can be reached at 515-4615 or by e-mail at bill.hess@svherald.com.
TheSilverRose wrote on Jun 27, 2009 10:22 PM:
Thank You! "