An environmental group has gone to federal court to block the use of motorized towboats in the Boundary Waters Canoe Area Wilderness as soon as the ice goes out on the 17 lakes where the service has been allowed for decades.

The request for a preliminary injunction by Wilderness Watch is in the hands of a federal judge in Minneapolis, and it's strongly opposed by the U.S. Forest Service. Superior National Forest officials say the towboat system assists people who have mobility shortcomings and helps disperse visitors deep into the million-acre wilderness — away from overcrowded edges.

A ruling in favor of Wilderness Watch would undo the plans of thousands of Minnesotans who have already booked towboat-assisted trips with BWCA outfitters.

"Wilderness Watch and its members presume the only way to experience the BWCAW is the way they want to experience the BWCAW," Assistant U.S. Attorney David Fuller wrote in a recent court filing.

The request by Wilderness Watch to immediately halt towboat service grew out of its broader lawsuit alleging that the Forest Service has not only sidestepped statutory limits on all motorboat use but has allowed commercial operators to expand activity that disrupts the solitude of the Boundary Waters.

The Forest Service has countered that it has continually refined and improved its system of permitted towboat management so as not to degrade the wilderness. It says the number of towboats permitted for use on wilderness lakes has dropped "substantially" from 91 in 1992 to 63 boats in 2019, operated by 18 approved operators.

The small-horsepower boats carry canoeists on prescribed routes to circumvent paddling over long distances. The canoes are hauled on the boats' overhead racks, then dropped on the edges of paddle-only lakes.

According to court filings by Wilderness Watch, if the injunction is not granted before the 2023 paddling season opens, its own members and all other visitors who seek a "primitive and unconfined type of recreation" would have their connections to the wilderness disrupted by "the noisy parade of commercial towboats the Forest Service has improperly allowed to proliferate."

Kevin Proescholdt, the Minnesota-based conservation director for Wilderness Watch, has said towboat traffic in the BWCA appears to have tripled since the early 1990s. His organization first sued the Forest Service over the issue in 2015, but it contends the Forest Service never followed through on settlement terms. "They've just allowed it to continue to grow," he said.

Asked what would happen to the canoeing plans this year of BWCA enthusiasts who have already booked towboat-assisted trips through outfitters, Proescholdt said they could avoid canceling by planning more time for paddling.

Despite the length of litigation in the case, no clear picture has emerged over the extent of motorized towboat usage, or which way it is trending. The Forest Service has admitted that its assessments of towboat service before 2015 weren't consistent. The Forest Service said earlier this year that its next use report on commercial services in the BWCA would be issued sometime in April.

According to research by Wilderness Watch, Forest Service monitoring reports show 2,550 commercial towboat trips in 2012, increasing to 3,865 in 2020.

But according to the recent court filing by the Forest Service, there were 3,815 towboat trips in 2020, down from 4,817 in 2019.

The Forest Service said in its court filing that Wilderness Watch cannot claim urgency in needing to stop all towboat usage. There are areas of the BWCA that truly classify as pristine wilderness, the agency said in its court filing, but even if towboats were removed from their existing routes, those areas would be "far from pristine."