Operators of the Moccasin Creek Dam issued an "imminent failure" warning Thursday, but that status was downgraded to "potentially hazardous" according to Tuolomne County Sheriff James Mele.
There were some evacuations. Peter Tira is with the Department of Fish and Wildlife. He says the department operates a hatchery downstream that holds one and a half million trout of all ages.
"We evacuated all nine of our employees and their families who live and work at the hatchery or right nearby the hatchery,” he explained.
The San Francisco Public Utilities Commission operates the dam and says it observed the reservoir "leaking" at about one o'clock this afternoon.
The commission says heavy rains caused a lot of water to enter the Moccasin Reservoir along with a lot of debris. Water began spilling over the primary and emergency spillways.
Water was receding at last check, but if the dam fails, the commission says Lake Don Pedro would handle the flood waters without a problem.
The National Weather Service says Highway 49 has been flooded due to outflow from the emergency spillway. Highway 120 may be also be impacted.
Sheriff Mele reported some streets also became inundated with water.
"There was a "basically a river running through downtown Groveland," Mele said.
He also says some students in the county were forced to shelter in place as buses were unable to reach them.