Bonneau dam project begins in May

After 10 years of planning, Bonneau Dam in the center of Rocky Boy's Indian Reservation will be enlarged beginning in May, tripling the capacity of its reservoir.

The dam's embankment will be raised this year, increasing the capacity from 956 acre-feet to 3,800 acre-feet, said Bruce Sunchild Sr., the tribe's water resource committee chair.

The majority of the water will be used for irrigation of alfalfa on the reservation, which will then be sold to Rocky Boy ranchers at a discounted price, Sunchild said.

About 700 acres of alfalfa are irrigated with water from the reservoir at this time. The increased capacity will hopefully increase the number of irrigated acres to more than 1,250, said Jonathan Eagleman, the tribe's water resources manager.

"In the past we didn't have a good irrigation system so we couldn't maximize on the alfalfa we were growing down there," Sunchild said.

He said in the past alfalfa had to be brought in from Canada, and that although some may still need to be trucked in, the extra alfalfa will be an improvement.

"The majority of ranchers in Rocky Boy will benefit," Sunchild said.

There are about 38 ranching families on the reservation now, said tribal natural resource director Robert Belcourt.

"This will definitely make a difference," Eagleman said. "This is an effort to improve the quality of life along Box Elder Creek drainage."

Sunchild said some of the water will be leased to downstream users, but that most of it will be used for irrigation on the reservation.

The drainage includes land between the reservation and the Milk River to the north.

"Anybody downstream of Bonneau Dam will serve to benefit," Eagleman said. "In the past it hasn't been managed to this degree ever."

The project, which will cost between $8 million and $9 million, was funded by a federal appropriations bill that passed about three weeks ago, Sunchild said.

Three other dams on the reservation - East Fork Dam, Toe Dam, and Brown Dam - are also planned to be enlarged in the next five years with federal funds under the tribe's water rights settlement, he said.

Eagleman said the project allows the tribe to develop its water resources, as well as stimulating the local and regional economy.

"It epitomizes the value of (tribal) self-governance," he said.

The main work items include excavating a spillway, producing the materials for the new earthen dam, raising the embankments about 36 feet, and topping the dam and spillway with rolled concrete, Eagleman said.

Work is expected to take about two years. This year the embankment will be raised, and next year the compacted concrete will be added, Sunchild said.

In addition to the benefit of developing water rights, the project will create jobs.

The work will be carried out by the Chippewa Cree Construction Co., and will employ as many as 28 workers, all of whom will be from the tribe, Sunchild said.

"We're going to try to make it as local as possible," he said.

The project originally came about as a result of safety concerns about the dam, Eagleman said.

In 1995 Bonneau was classified as one of the "high-hazard" dams in the United States by the federal Bureau of Reclamation. At the same time, the tribe was negotiating its water rights with the federal government. It was able to negotiate a plan that would correct the dam's deficiencies and also enlarge it, Eagleman said.

The dam was classified as dangerous because there was seepage along the dam's right abutment, the outlet works were inadequate for the amount of water in the reservoir, the spillway wasn't adequate, and there was no overtopping structure to prevent a breach of the dam.

The seepage has been corrected, and the outlet works have been fixed, Eagleman said.

That happened in 1995 and 1996, Sunchild said.

The spillway and the overtopping structure will be built as part of the construction that has just been approved.

Information from The Associated Press was used in this story.