PPL Montana will lower the elevation of the Rainbow Dam reservoir near Great Falls starting Aug. 23 to support the ongoing construction of the new Rainbow powerhouse facility.

The planned drawdown will reduce the Rainbow reservoir elevation by 8 feet. The drawdown will take about a day and a half to lower the reservoir level to the temporary elevation.

The reservoir will be maintained at the temporary elevation until mid-November to support construction of the new Rainbow powerhouse.

“For safety reasons, the Rainbow boat launch on Rainbow Dam Road will be closed because water levels will be too low to navigate boats safely on the reservoir,” said David Hoffman, director of External Affairs for PPL Montana. “We apologize for any inconvenience this may cause boaters and fishermen, but safety is our priority during construction work at Rainbow.”

Boaters and fishermen can call the Montana Department of Fish, Wildlife & Parks at 454-5840 for information about fishing conditions on the Missouri River.

The drawdown will be implemented under PPL Montana’s agreements with its partner agencies and the Federal Energy Regulatory Commission.

PPL Montana is redeveloping the Rainbow facility — a symbol of Montana’s commitment to hydroelectric energy for 100 years — as part of a $230 million project that will increase by 70 percent the amount of clean, renewable power that can be generated at the plant and improve passage for fish on the Missouri River. The project is expected to be completed in 2012.

A new powerhouse, with a single 62-megawatt unit, will replace units installed between 1909 and 1930. It will be big enough to power about 45,000 homes.

PPL Montana provides safe, reliable energy from coal-fired power plants at Colstrip and Billings, as well as 11 hydroelectric plants along West Rosebud Creek and the Missouri, Madison, Clark Fork and Flathead rivers. It has a combined generating capacity of more than 1,200 megawatts and has offices in Great Falls, Billings, Butte and Helena. PPL Montana and its 500 employees are dedicated to Montana and its communities, supporting educational, environmental and economic development programs across the state. PPL EnergyPlus operates a trading floor in Butte that markets and sells power for PPL Montana in wholesale and retail energy markets throughout the western United States. PPL Montana and PPL EnergyPlus are subsidiaries of PPL Corporation.