EL DORADO — What would make a well designed to monitor ground water levels show an increase of about 100 feet in a few days?
Who knows?
“It’s not an emergency, but it’s still a mystery until further investigation,” said Sherrel Johnson, grants and special projects manager for the Union County Water Conservation Board, after recently meeting at the well site – a non-pumping water well – with other “water watchers.”
Members of the Union County Water Conservation board are working with the U.S. Geological Survey and other Union County
residents who monitor water wells to find out why the well at the Arkansas Welcome Center on U.S. 167 south of El Dorado measured “more or less a 100 foot rise level” during October, Johnson said.
The “real time” well is a pipe in the ground that is used just for monitoring the water level of the Sparta Aquifer – the source of drinking water for south Arkansas and north Louisiana.
Johnson said the groundwater level at the well on Oct. 10 (ground surface to top of water) was 317.36 feet and “it had been consistently around 317 feet – give or take – for weeks.” The groundwater level Oct. 11 was 176.31 and on Nov. 30, it was 124.56 feet.
The U.S. Geological Survey maintains records sent from a computer (powered by a solar panel) at the well site, said Bill Baldwin, hydrologic data chief with the USGS office in Little Rock, who made the trip to El Dorado recently to open the well house where the pipe is located. He said readings on the water level at the well are sent to Little Rock hourly and when they noticed the sudden increase in the Sparta level at the Welcome Center, an investigation began.
According to Johnson, Anna Nottmeier, hydrology tech at the USGS, said that the well depth is “actually 806.8 feet and has a total hole depth of 829 feet.”
Baldwin removed the transducer (a device that converts variations in a physical quantity, such as pressure or brightness, into an electrical signal, or vice versa) and the casing from the well and explained that the transducer transmits ground water levels.
When Kelly Arnold and Claudie Gray with Keithville Well Service in Louisiana arrived at the well site, they used a down-hole camera to look inside the pipe to see if there were any defects in the pipe that might cause the water level to rise. They saw no breaches in the pipe as far as the down-hole camera would look – 500 feet. Arnold said if there is a leak in the pipe – if the casing has been compromised – it usually occurs within 100 feet from the top.
“It was music to our ears that Kelly kept saying, ‘This is good water. I’ve seen lots of wells and well water and this is excellent water’,” Johnson said.
Water watchers on the scene – including Johnson, Baldwin, Ginger Risinger (hydrology tech who measures water levels at several wells in this area) and Michelle Fisher (hydrology field tech assistant) – began discussing several possible reasons why the water level readings might increase, including flushing wells near the monitor site.
Johnson said that Rob Reynolds, advisor and founding and former member of the Union County Water Conservation Board, said that even if “every Sparta well in Union County shut down at the same time, it wouldn’t be enough to result in that kind of water level rise, particularly that fast.”
A shift in a fault line was also suggested as another possible reason for the elevated water measurement, but after some checking, Baldwin said he looked on the website for USGS Earthquake reports during the time of the increased water reading and “nothing was reported near that area for the months of September and October.”
Reynolds said unless an earthquake was strong enough for local residents to feel, a deep underground shift would be highly unlikely to cause that kind of rise.
So the mystery continues for now.
“USGS will continue its investigation using a conductivity and temperature probe that can be lowered to 700 feet. Changes in temperature and conductivity will be easily detectable near a hairline fracture, even if the fracture is undetectable by a camera. This work will likely occur after Christmas, and we hope to have a full report ready for the (Union County Water Conservation) board’s quarterly meeting Jan. 18, including options for the board’s consideration,” Johnson said.
“The Welcome Center well is not only geographically important to monitoring the Sparta’s response to Union County’s efforts to conserve and protect the county’s pristine drinking water source, it is important for education and field briefings,” she said.
The Sparta aquifer is a primary source of ground water for industrial, municipal and agricultural uses in southern Arkansas and northern Louisiana. In Union County, withdrawals from the aquifer at one time resulted in the decline of ground water levels of over 250 feet in this area and in 1996, the Arkansas Soil and Water Conservation Commission designated this area as a critical groundwater area.
In 1999, a group of 11 local residents formed the Union County Water Conservation Board and in the span of a few years, water taken from the aquifer went from 21 million gallons per day to eight to nine million gallons per day. The project to save the Sparta included a 26-mile pipeline, an intake structure, water treatment facility and storage tanks, monitoring wells, the vote of the people to approve a one-cent sales tax and the willingness of four local plants – Lion Oil, Great Lakes Chemical, El Dorado Chemical and Entergy Power Partners – to use water piped from the Ouachita River instead of the Sparta. Water is also supplied from the river to irrigate Mystic Creek Golf Course and residential area and practice fields at El Dorado High School.
The U.S. Geological Survey monitors the ground water level of the Welcome Center well and several others.
Additional information can be found at http://ar.water.usgs.gov/sun/sparta_recovery/center/index.phtml
www.ucwcb.org