PPL Montana begins next phase of work at Hebgen Dam

PPL Montana has identified the source of the problem — damaged logs, called stoplogs — in one of the bays in the intake structure at Hebgen Dam, and the company has begun making repairs.

New stoplogs are being placed in a safe and controlled manner, as part of a plan to reduce water flow gradually. Stoplogs, which are 12 inch by 12 inch wooden beams similar to railroad ties, are stacked and used to regulate water flow.

The dam remains safe and stable, according to on-site monitoring equipment, and the concrete piers of the intake structure are sound.

PPL Montana employees, structural engineers and experts in dam construction have been working since Aug. 31, when the problem in the intake structure was discovered, to determine the safest and most effective approach to stem the flows.

The company is communicating with local, state and federal officials and those who depend on the river for business and recreation as work continues on the intake structure.

“PPL Montana understands the inconvenience this has caused and appreciates the interest and patience of everyone who depends on Hebgen Lake and the Madison River,” said Brad Spencer, PPL Montana’s vice president and chief operating officer.

As a result of the increased water flow from the lake, the water elevation level in the lake has dropped below the minimum recreational level. PPL Montana has notified the Federal Energy Regulatory Commission and other agencies of the situation and made personal contact with marinas and homeowners to remove their boats as lake levels drop.

Engineering work continues on a longer term solution to replace all the timber stoplogs currently in service in the intake tower. When the intake structure is repaired, PPL Montana will operate the dam to balance the needs of recreational users of Hebgen Lake, and the need to protect important trout habitat downstream on the Madison River.

The U.S. Geological Survey has information, updated every four hours, on the Web about river flows and lake elevations.

For river flows, click here.

For lake levels, click here.