By AP/KWMU
St. Louis – Missouri inspectors say they were "shocked" to discover that the portion of a collapsed reservoir was made from rocky fill material. They say they had assumed for decades it was granite.
The state's chief dam and reservoir inspector, James Alexander, says the entire 660-foot wide section that failed appeared to consist strictly of soil and smaller rock.
He inspected the site after the accident on Wednesday.
AmerenUE says it will address Alexander's concern as part of its investigation.
The upper reservoir of the utility's Taum Sauk hydroelectric plant breached this week, sending a billion gallons of water rushing down the side of Proffit Mountain.
A five-year-old boy injured during that accident remains in critical condition, but his brother and sister continue to improve.
Three-year-old Tara Toops and her seven-month-old brother, Tucker, were upgraded to fair condition Wednesday at Cardinal Glennon Children's Hospital in St. Louis.
Hospital spokesman Bob Davidson says the two youngsters have been moved out of the pediatric intensive care unit to a regular nursing floor.
Their five-year-old brother, Tanner, remains critical.
All three children were in critical condition with hypothermia when they arrived from southeast Missouri Wednesday. Their home was washed away during the reservoir failure.