SALT LAKE CITY (AP) — Workers hastily tried to shore up a rural Utah dam after a 60-foot crack opened and sent water spilling into a creek, endangering the 1,700 inhabitants of a town downstream.
State and local officials do not believe the Panguitch Lake Dam is in imminent danger of opening, but have told residents to prepare to evacuate if conditions deteriorate. Lowering the reservoir below the affected area will take several days, said Everett Taylor, assistant engineer for dam safety with the Utah Division of Water Rights.
About 2 feet (61 centimeters) of water remained above the fissure Wednesday evening and they had covered nearly 45 feet (nearly 14 meters) of the fissure with rocks, he said.
An ice sheet on the reservoir was pushing against the dam, causing the top to crack and tilt downstream, with water gushing through the opening, Taylor said. The ice sheet has now moved away from the dam and the top of the dam has tilted backward, he said.
“We cut off that ice sheet so we could relieve the pressure on the dam,” Taylor said.
A community meeting was planned Wednesday to take stock and answer questions from residents of Panguitch, a town of about 1,800 located about 10 miles (16 kilometers) downstream from the dam. Another small town, Circleville, is further downstream and faces less risk.
Local officials discovered the crack in the upper portion of the dam during an inspection Monday evening, and Utah state officials announced it to the public Tuesday.
Water is released at a rate of nearly 260 cubic feet (6.5 cubic meters) per second to lower the reservoir below the fissure, and large rocks are trucked in and placed on the downstream side of the dam to support the wall. No rain is forecast until Saturday.
The dam was built in the late 1800s, but the cracked top was added to the top of the dam in the 1930s and 1940s. There were no previous concerns about the structural integrity of the dam, Taylor said .
“No one anticipated this,” he said, adding that he was encouraged by the progress being made.
State officials called it a Level 2 failure risk — a designation in the middle of the three-pronged scale that means there is a risk of the dam failing.
“We’re going to continue to focus on lowering the reservoir, making sure that the ice … we keep it out of the dam and continuing to reinforce or support that downstream side,” Taylor said.
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Peterson reported from Denver.
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