Officials tour St. Mary Diversion

BLACKFEET INDIAN RESERVATION - The massive, rusted steel pipe nestled in the foothills of the Rocky Mountains shakes from the force of the water rushing through it.

Near the top of its downhill slope, the 90-inch siphon periodically jerks because of turbulence in the water, as if a giant knuckle is tapping it. Near the bottom of the downhill slope, before the siphon crosses the St. Mary River and runs up the other side of the valley, the 80-year-old pipe sways as the water races through it. Along the length of the pipe, water hisses as high pressure forces it out of expansion joints in the sip...