Neihart fish barrier proposed to save last of Belt Creek's Western cutthroat trout

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Montana Fish, Wildlife and Parks is seeking public comment on a draft environmental assessment on a proposal to construct a concrete fish barrier on Carpenter Creek in the Little Belt Mountains.

Carpenter Creek, a tributary to Belt Creek, is downstream of the town of Neihart and currently supports one of the last genetically pure populations of native Western cutthroat trout in the Little Belts.

According to the draft Environmental Assessment, which is available to the public on the FWP website https://fwp.mt.gov/news/public-notices, genetically unaltered WCT (Western Cutthroat Trout) presently occupy 6.2% of their historic habitat within the Belt Creek watershed. Carpenter Creek is one of 10 streams within the Belt Creek watershed that still supports an unaltered WCT population; however, the population is comprised of only an estimated 591 fish, which are confined to the upper 1.5 miles of stream.

For more than 60 years, WCT populations in the Little Belts have been isolated from Belt Creek by mining that resulted in poor water quality unable to support fish.

“Historic mining within the Carpenter Creek drainage has resulted in the lower 3.2 miles of stream contaminated by effluent from at least 21 abandoned mines,” the draft EA states. “This chemical barrier has prevented the upstream movement of nonnative trout from Belt Creek."

The mines are no longer in operation, but recent mine cleanup activities have had the unwanted impact of removing the current chemical barrier that isolates the native trout from nonnatives in Belt Creek.

“As cleanup activities have progressed and water quality has improved, nonnative trout have begun moving into lower Carpenter Creek from Belt Creek,” the EA states. “Through a combination of competition and hybridization, the establishment of nonnative trout in Carpenter Creek will eventually lead to the extirpation of this unprotected population of native WCT."

Since the late 1800’s, numerous nonnative fish species have been introduced throughout the Belt Creek watershed. Nonnative brook, brown, rainbow, and hybrid trout have now become the dominant species in most streams historically occupied by WCT.

“Brook and brown trout displace WCT through competition or predation,” the barrier proposal explains. “Rainbow and Yellowstone cutthroat trout readily hybridize with WCT which results in populations entirely comprised of hybrid individuals (hybrid swarm) or mixed populations of hybrid and genetically unaltered fish.”

Fish, Wildlife and Parks note’s that the strongest remaining WCT populations in Montana are those isolated from nonnative species by natural or manmade barriers, and that the likely long-term survival of genetically pure populations of Western cutthroat trout not protected by barriers is questionable.

“Construction of a concrete fish barrier in Carpenter Creek would secure the nonhybridized WCT population by preventing the upstream movement of nonnative trout,” the EA states. “As the mine cleanup activities continue, an additional 1.7 miles of habitat would be available in Carpenter Creek for WCT as well as 4.8 miles of tributary habitat (Snow, Lucy, Mackay, and Burg Creeks).”

FWP suggests the construction of a concrete fish barrier on Carpenter Creek would potentially bring the total number of unaltered WCT in the Belt Creek drainage to more than 2,500 fish, which would greatly increase the population’s likelihood of long-term survival.

"Protecting this population of cutthroats would secure an invaluable component of the Belt Creek watershed’s natural heritage for future generations to enjoy," the EA states. "Moreover, conservation of native cutthroat trout brings a range of benefits to local communities and is required under state and federal law."

Additional printed copies of the draft Environmental Assessment are available at Montana Fish, Wildlife & Parks office in Great Falls, located at 4600 Giant Springs Road. The draft EA is also available on the FWP website at https://fwp.mt.gov/news/public-notices.

A public review and comment period will be available Jan. 11-Feb. 10. Written comment should be delivered to the following address: Montana Fish, Wildlife & Parks, R-4 Fisheries, Carpenter Creek Westslope Cutthroat Trout Conservation, 4600 Giant Springs Road, Great Falls, MT 59405, or by email at fwpr4publiccom@mt.gov.

This article originally appeared on Great Falls Tribune: Proposed fish barrier could save Montana's last native cutthroat trout

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