EPHRATA - Grant County Public Utility District officials said there is no threat of widespread flooding or property damage below the cracked Wanapum Dam spillway.

"Even if the worse case scenario happened and that part of the dam collapsed into the Columbia River, the water level would be within normal rainfall levels for this time of year," Grant PUD spokesman Thomas Stredwick said Sunday.

What caused the crack is still under investigation.

"Identifying the cause is instrumental in figuring out the source of the damage," Stredwick said. Figuring out what caused the crack would help engineers fix it.

Divers found the crack that spans the entire width of the 65-foot spillway about 70 feet below water level last week. Engineers noticed a slight bend or bow in the upper level of the spillway during routine inspections Feb. 25.

Stredwick said that even if the cracked spillway breaks, the other 11 spillways, which allow water to flow past the dam rather than running through the turbines, would stay intact and continue to handle runoff flow.

Grant PUD and Federal Energy Regulatory Commission engineers worked through the weekend to monitor water levels and looked into what caused the crack.

Engineers lowered water level 20 feet over the weekend to lessen the pressure on the damaged spillway. It continues to produce electricity.

All boat launches on the Priest Rapids and Wanapum reservoirs are currently closed because of low river elevation.

The Wanapum Dam is the most productive that Grant PUD operates. It produces enough power for 800,000 homes, Stredwick said.

District spokesperson Chuck Allen said the drawdown will diminish the PUD's power production. He said the PUD is already buying power on the wholesale market to make up the difference.

Ted Escobar, of the Royal Register, contributed to this article.