David MurrayGreat Falls Tribune
It’s been nearly 100 years since the waters of the Missouri River began rushing over the spillway at Black Eagle Dam. Throughout that time the dam has been a trustworthy source of clean, reliable electricity for the people of Great Falls.
Yet there is a singular peculiarity about Black Eagle Dam that has proved troublesome at times. It is the only one of the 11 hydroelectric dams NorthWestern Energy operates where a large quantity of river ice periodically builds up on the upstream side, threatening to block the river from efficiently flowing over the spillway.
When winter temperatures plunge into the single digits, NorthWestern crews must walk out onto Black Eagle Dam's crest and chip away the built-up ice using a small crane and long iron bars. When temperatures drop below zero the frigid task sometimes needs to be done twice a day.
The solution will be a major upgrade and enhancement of the Black Eagle Dam’s spillway, one that is expected to take two years to complete and will require the use of a barge to ferry equipment and materials down the Missouri River to the upstream face of Black Eagle Dam. Construction on the barge landing has already begun.
“The project is going to be installing new support structures and components for the spillway,” explained NorthWestern Energy spokesperson JoDee Black. “This project will not only enhance the dam itself to serve Montanans for the next century, but also it will eliminate the need for that manual ice removal. It’s to improve the efficient operation of the dam, and the safety of the workers to eliminate that ice chipping task when its bitter cold out.”
Already a heavy industrial excavator has begun work on the Missouri’s north shore, digging out a level base for the landing where the barge will eventually be loaded and stored. The motivation to incorporate a barge in the project is due to the difficulty of reaching the dam from the surrounding shoreline.
“The accessibility with the terrain on either side of the dam makes a barge carrying equipment in the river itself a much better choice,” Black said. “Once the barge arrives it will go into the river right there. That will be the barge launch and landing area. It will stay in the river most of the year. As the river ices up, it may need to come out to be in that landing area.”
The site where the barge landing is being constructed is directly adjacent to the River’s Edge Trail. That close proximity means there will likely be short closures of the trail when heavy equipment is being moved back and forth from the barge landing site.
“People use this part of the trail all of the time,” said Black. “We want to answer their questions about what’s going on and let them know that there could be short interruptions. You might have to wait for a truck to pass or something else at this point, but from now to the end of June there’s no plan to have extended closures of the River’s Edge Trail at that spot. What we want people to know is this is occurring, and we appreciate their flexibility.”
Ensuring the trail is not damaged while the spillway enhancement project takes place is another priority for NorthWestern Energy. Crews have placed temporary metal overlays across the River’s Edge Trail to protect it from the heavy equipment.
“The project will take two years. When it’s all done those metal overlays will come off and everything will be returned back to its original condition,” Black explained. “Right now, there are short intermittent closures of the trail of much less than an hour if a construction vehicle is needing to cross it. If there is going to be a longer closure, we’ll let the recreating public know. We have a website page about the project at NorthWesternEnergy.com.”
She also noted that the current dam was not the first to occupy that section of the Missouri River. The original dam at Black Eagle Falls was a timber and rock crib dam that was completed in 1890. It was first hydroelectric dam built in Montana, and the first on the Missouri River.
The existing concrete dam was built slightly downstream from the original Black Eagle Dam site. It was completed in 1926 and became fully operational in 1927. The old timber and rock Black Eagle Dam was never removed from the river bed and now lies submerged in the reservoir.
The completion of the ongoing spillway project will coincide with the 100th anniversary of completion of the existing Black Eagle Dam.
