The installation of a "poiree needle system" at the Thatcher Lock and Dam has set a temporary barrier to allow the United States Army Corps of Engineers to begin work to fix a leak that has resulted in low water levels in the Ouachita River pool above Thatcher dam.
Robert Reynolds, a volunteer advisor to the Union County Water Conservation Board (UCWCB), as well as the board's founding president, said Wednesday that the poiree needle system will hold the Thatcher pool above 71 feet above sea level, acting essentially as a temporary dam.
In October, a leak in the hinged crest gate at the lock and dam allowed the Ouachita River to begin falling to levels that could have potentially threatened the drinking water supply in Camden and impacted UCWCB infrastructure in Calion.
Camden residents get their drinking water from the Ouachita River via an intake system in the city, while everyone in Union County's drinking water comes via the Sparta Aquifer. The UCWCB does, however, have an intake pumping system in Calion that draws water out of the Ouachita River for local industries.
Usually, the hinged crest gate would maintain the Thatcher pool water level at 77 feet above sea level. The permanent concrete dam structure prevents the pool level from falling lower than 71 feet above sea level.
A statement released by the U.S. Army Corps of Engineers (USACE) last month said that once water levels fell to 71 feet and the hinged crest gate was exposed, inspections would begin immediately, with repairs following as soon as possible.
On Wednesday, the USACE announced that it was continuing to monitor water levels at Thatcher following the poiree needle system's installation. Reynolds said he didn't know the condition of the hinged crest gate leak on Wednesday, but noted that no matter the water level, the leak will be able to be fixed with the poiree needle system in place.
"With this poiree needle system, they (USACE) can perform the work they need to with the current water levels, whether that's 71 feet, 72 feet, 73 feet," he said. "I think they've got the barrier they need that will allow them to do the work. That's my interpretation."
Several local industries use water from the Thatcher Lock and Dam, including Delek: El Dorado Refinery, the LANXESS Central plant, El Dorado Chemical and the Entergy/Union Power Partners power plant, which was built at the same time as the UCWCB's infrastructure in Calion. Additionally, the new El Dorado High School, Mystic Creek Golf Course, Mystic Creek residential development and Holly Falls, a local wedding venue, use the river water for irrigation.
Reynolds said no industries had been affected by the dam leak as of Wednesday.
"We're on pins and needles of course, because (the water level) has never been that low, but we believe that we're in a position to operate when the water level is only 71 feet and continue unabated," he said.
The intake pumping system at Calion, additionally, is at 67 feet above sea level; according to a statement Reynolds presented to the UCWCB last month, it's believed the system will continue to pump water so long as the dam pool is higher than 67 feet, though that hasn't been tested since the intake system became operational in 2002.
He said last month that he didn't anticipate local industries being affected by the Thatcher leak.
Reynolds also noted Wednesday that during to a draw down -- where the surface elevation of a body of water is lowered -- performed by the USACE at the Thatcher Lock and Dam last week, the UCWCB was able to observe a sandbar in front of the intake structure that hadn't been seen before and that could have potentially caused problems.
"We could see something that we did not know existed: there was a naturally deposited sandbar in the river in front of the Union County Water Conservation Board's intake structure," he said. "Even though the system was designed to flow when the water level was down to 67 feet, we've never been stress-tested."
He said the board sought and was granted emergency authorization from the USACE to knock some of the sandbar away.
"We really could not accurately measure by observation; it's hard to tell how deep the water is on top of the sandbar, and it was too close for comfort," Reynolds said. "So far so good ... but just in case, we did knock a hole in the sandbar."
Reynolds said that per USACE drafts of the repair plan, the leak could be fixed by the end of the year, barring major rain events.
"We've been in -- I would call it a normal seasonal drought, maybe a little longer," he said. "If we receive some pretty good rainfall in the Ouachita River drain basin, that could hurt their work and make it delayed, but right now, the sun is shining, birds are singing and we have two weather systems that are keeping us warm and dry."
According to the National Weather Service, the water level at Thatcher Lock and Dam was 74.4 feet at 4 p.m. Wednesday, and it was projected to stay at about that level through Sunday at least. Slight chances of rain were forecast for Friday and Saturday.
Camden Mayor Julian Lott said in a statement on Wednesday that he is grateful for the work the USACE and others have done to ensure the city can continue to access potable water.