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PPL Montana says temporary repairs on the Madison River Dam below Ennis Lake will begin next week.

A large crane will be used to lower 3,000-pound bags of concrete around the rock that damaged the dam early Monday. The concrete will seal off the area where waters are flowing over the remnants of the dam.

Geologists will inspect the cliff from which the bus-sized rock fell on the dam to determine if there's a danger of more rocks falling in the future.

These pictures show the level has dropped five feet since Monday

PPL Montana also says it will reopen access to the Upper Bear Trap Canyon for the Labor Day holiday weekend. The company made the announcement in a news release this morning:

"Safety of the public and employees continues to be the top priority as we move forward with plans to repair Madison Dam," said David Hoffman, director of External Affairs for PPL Montana. "In consultation with the Federal Energy Regulatory Commission, state and federal regulatory agencies, geologists and other experts, PPL Montana has determined that conditions are safe for public use of the road, and that's good news for the Labor Day weekend."

Equipment atop the west side of the dam was damaged by a falling boulder from the wall of Bear Trap Canyon early Monday (8/30).

The road will be opened at 7 a.m. Saturday (9/4) and remain open until sunset on Monday (9/6). The road will remain closed on weekdays to allow construction equipment to access the dam. It may reopen on weekends after Labor Day, depending on the status of the work being done at the dam.

Hoffman said PPL Montana is sensitive to the importance of the fisheries, angling and boating on this popular section of the Madison River, and to the local economy.

"We're pleased that we can open the road for the holiday weekend," Hoffman said. "We ask the public to be mindful, however, that that road will be closed during the week so we can bring equipment to the dam. We plan to post signs by the Trail Creek trailhead with information about the status of the road."

Meanwhile, PPL Montana will complete a 5-foot drawdown of Ennis Lake by Friday night as the first step in the company's plans to remove the boulder and repair the damaged equipment on the dam. To reduce pressure on the dam and the boulder, PPL Montana began to draw down Ennis Lake behind the dam on Monday evening.

The current flow rate of 3,300 cubic feet per second should limit effects on fishing and recreation on the lower Madison River, but the drawdown will affect boat docks and public launch sites on Ennis Lake. Flows will be reduced even further over the weekend - to near 1,400 cubic feet per second - once the drawdown is complete.

"Working with geologists and other experts, we've also determined that another large rock above the dam is anchored to the canyon wall," Hoffman said. "That will allow us safe access to make repairs."

Damaged equipment on the dam includes three spill gates, walkways and wooden flashboards that sit atop the dam to raise the level of water it is able to hold back.

PPL Montana is coordinating its efforts at Madison Dam with regulatory agencies and law enforcement officials from the state and local level up to FERC, which is responsible for oversight of hydroelectric facilities.

Madison Dam is a four-unit hydroelectric plant on the Madison River at the head of Bear Trap Canyon about 10 miles north of Ennis. The units have a total generating capacity of 9 megawatts. Madison Dam is 257 feet long and 35 feet high."