The city's poplar plantation and its ties to the wastewater treatment facility could see the material used more as compost and stream bank stabilization than lumber, as first envisioned seven years ago when the facility was established.

While those changes remain in flux, the Missoula City Council on Wednesday agreed in concept to hand the arboreal duties that come with managing the plantation to the city. They also agreed to realign the contract to match the city's fiscal year, not the calendar year as before.

Dennis Bowman, deputy director of Public Works, said the changes are intended to save money. The original agreement had a contracted arborist performing the maintenance duties. Those will be passed on to a city arborist with the Department of Parks and Recreation.

“In the past, they used to have an arborist come in,” said Bowman. “That arborist would say we needed to do all this work and I felt there was some conflict of interest there because the work he pointed out – he got the work. We're trying to be as efficient as possible.”

The poplar plantation was established around 2013 to help Missoula meet federal regulations regarding wastewater. The city is permitted to discharge wastewater into the Clark Fork River, though it's required to monitor for various nutrients.

If the city fails to meet those guidelines, Bowman said, it could be on the hook for massive wastewater improvements topping $50 million and more. In a novel experiment, the city began directing more than 1 million gallons of effluent from the treatment plant to the plantation to water the hybrid forest.

Those trees have grown tall, thick and green over the years, absorbing nutrients in a closed system while sequestering carbon. Now, the future use of those trees is shifting.

“Since the market changes, we can't use it much for board – there's not much of a call to use it for regular lumber and that,” said Bowman. “With the approximately 80,000 trees that are out there, in the future we'll need that for the compost facility. We're not going to go in there and cut everything down, because that would ruin the appearance.”

Bowman said current plans will remove 80 popular trees that are ready to topple. The cost of their removal will serve as a benchmark for a future harvesting plan.

“My goal is to look at the cost of taking 100 trees out, or 500 trees out, and do it strategically throughout the plan,” Bowman said. “We have to look at this not only for this year or next, but five years from now and 10 years.”

John DiBari, a former City Council member who now helps manage the poplar plantation, said the facility has seen a conceptual shift on how it's operated. The changes have been evolutionary and market driven, he said, and they've played out in partnership with the city.

“When we first started this project, we were looking at using those trees as saw logs and selling the actual timber for milling purposes,” DiBari said. “We're now re-envisioning how those trees are going to be used to cycle back for use in the composting facility. We've been adapting to changing market conditions and ways of doing management.”

While the trees may not be grown for lumber, using them as compost remains a plan in progress, and other aspects must also be addressed. The “supercharged nitrogen and phosphorous” directed to the plantation grows more than just trees, DiBari said, and aesthetic concerns post-harvest must also be considered.

“We do need to come up with a plan on how to harvest those trees, where to harvest those trees and how many to harvest,” he said. “We need to implement that plan going forward so we're providing a sustainable supply of wood to the compost facility, but not also changing the look and feel of the poplar plantation as well.”

A number of trees taken from the plantation will also be used to stabilize the stream bank as the old Rattlesnake Dam is removed. The plantation also grows willows, which will be used for restoration at the construction site.

DiBari said efforts to fine tune the plantation's new management plan and ensure it adheres to current conditions will continue to unfold.

“It's an opportunity for us to close the circle and use those trees in our own compost facility,” he said. “There's years and years worth of supply out there to supply the compost facility. We'll start small and figure out how the labor and costs associated with that are and how it benefits the compost facility.”