In response to above-normal June precipitation and later-than-normal heavy mountain snowpack, PPL Montana will be forced to increase flows into the downstream Madison River to help control water levels in Hebgen Lake.
“The excess precipitation this spring, around 150 percent of normal for the first half of June, combined with the large snowpack in the upper Madison River high country, has the potential to result in a Hebgen Lake elevation above our federal operating license limit of 6,534.87 feet if we do not increase outflows,” said Jon Jourdonnais, manager of hydro licensing and compliance for PPL Montana.
Jourdonnais said that, depending on weather patterns and the rate of projected runoff, PPL Montana will, over the next several days, adjust flows into the downstream Madison River to between 3,400 and 4,000 cubic feet per second at the Kirby U.S. Geological Survey gauge, on the river downstream of Hebgen.
“We remind the many people who use the Madison River for recreation and other uses to be mindful of these higher flows and use additional caution around the higher, faster moving water,” Jourdonnais said. “Our neighbors around Hebgen Lake should be aware that rising lake elevations may also affect shoreline properties. They should take appropriate precautions to protect personal safety, property, docks and boats.”
This plan for balanced Madison operations is designed to moderate possible Hebgen overfilling while at the same time reducing the need, as this late runoff season progresses, to release even higher downstream river flows, he said.
Although the current high inflow and outflow projections have delayed the start of the intake rehabilitation work this year at Hebgen Dam, the higher inflow conditions do not pose any additional concerns regarding dam safety.
In addition to the Federal Energy Regulatory Commission, the agency that licenses hydroelectric dams, PPL Montana has shared its short-term operating plan with its Madison River agency partners, including Montana Fish, Wildlife and Parks; the U.S. Forest Service; U.S. Bureau of Land Management; U.S. Fish and Wildlife Service; and the Montana Department of Environmental Quality.
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 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 (NYSE: PPL).