Experts Monitoring Wanapum Dam

At the top of this image of Wanapum Dam, a slight bend is noticeable in the conduit below the guardrail. This is the anomaly spotted by a Grant PUD employee that resulted in discovery of the crack.

The crack is at the bottom of the fourth spillway pier from the left in this photo.

BEVERLY, Wash. – Working in conjunction with the Federal Energy Regulatory Commission, and independent engineers, Grant PUD continues to inspect and evaluate the crack found on a spillway section at Wanapum Dam on February 27.

Preliminary engineering studies called for a drawdown of the Wanapum Reservoir on the Columbia River as a precautionary measure. By Monday, March 3, water levels above Wanapum Dam (forebay) are anticipated to be 20 feet lower than the normal high operating level to reduce the pressure on the spillway.

A spillway is the portion of the dam that allows water to “spill” past the dam as opposed to running through the turbines. The spillway consists of multiple, independent structural sections that support the spillway gates. Each of Wanapum Dam’s 12 spillway gates are capable of passing roughly 80,000 cubic feet of water per second based on current river conditions. In a worst case scenario, if one of the spillway sections failed, the remainder of the spillways and the main dam structure would remain intact. Under current conditions, the amount of water that would flow through this section of the dam would be within the range of normal river conditions.

The team of engineers and regulatory agency personnel are working through the weekend to provide constant monitoring and on-going evaluation of the area. Public safety is the utility’s paramount concern.

The dam continues to generate electricity without any additional constraints on electric generation except for reduced water levels behind the dam. All boat launches on the Priest Rapids and Wanapum reservoirs are currently unavailable because of the low river elevation.

MEDIA CONTACT: Thomas Stredwick

(509) 793-1571 /


(509) 754-5055

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