Authorities have discovered a crack at the base of the Wanapum dam in Washington State. Measuring 65 feet (or 20 meters) long and two inches (or five centimeters) wide, the crack is found specifically in the spillway of the hydroelectric power plant, which is located on the Columbia River. Officials started decreasing the dam’s water level by 20 feet to allow inspectors to assess the real amount of damage the dam is in.

While the Public Utility District  spokesperson of Grant County, Thomas Stredwick assured that the crack poses no harm or danger to the public, he said that the forebay is being lowered to lessen the pressure on the spillway during the investigation. The spillway is a crucial channel that enables controlled water release from a dam.

Earlier this week, The Seattle Times reported that one of the engineers working on the repairs spotted minor “bowing” right above the area of the spillway gates where vehicles pass through the dam. Divers were sent out to check the status of the crack on one of the spillway piers, so that public utility district officials could analyze their findings. They declared on Friday that the risk of failure was high enough to prompt notification to downstream water users and concerned government agencies.

Since the Wanapum Dam sits downstream from the town of Vantage in Washington, its failure would make a significant impact on farming, fishing, and power generation in the area. The dam has a generating capacity of more that 1,000 megawatts of hydroelectric power. It caters to more than 45,000 customers in Grant County and provides electricity across the Pacific Northwestern region.

The 55-year-old dam was named after the Wanapum Indians and did not officially operate until 1963. It has 10 spillway gates that are supported by multiple piers, which each has a height of 126 feet, width of 65 feet, and depth of 92 feet.

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