Stibnite Mine’s negative impact on native fish
A bull trout in the South Fork of the Salmon River, which is impacted by Stibnite Mine. Photo credit: Mary Faurot, Save the South Fork
The Stibnite Gold Project proposal by Perpetua Resources to mine the headwaters of the East Fork of the South Fork Salmon River (EFSFSR) was further analyzed by the Forest Service in a report known as a Supplemental Draft Environmental Impact Statement (SDEIS) that is currently open to public comment through January 10th, 2023. The project would be detrimental to the South Fork watershed, a biologically diverse ecosystem of great significance to many communities.
Learn more about the proposed Stibnite Gold Project, the threats it poses to an incredible river, and how you can take action here.
The South Fork is unique in that it is one of the few places in the Columbia Basin with virtually all of its native fish species still present. The run of chinook salmon up the river was once one of the largest in the region, accounting for 70% of all summer chinook in Idaho and one-third of the state’s sportfishing harvest. Indigenous people have hunted salmon, steelhead, and lamprey in the South Fork drainage for countless generations.
Anadromous fish runs on the South Fork are now a fraction of their former abundance, primarily due to impacts from the eight-dam hydrosystem downstream. Chinook salmon and steelhead are Endangered Species Act-listed and native lamprey have been released in the drainage by the Nez Perce Tribe since 2012 in an effort to restore the population.
Bull trout (ESA listed) and westslope cutthroat trout, designated a sensitive species by the Forest Service, also call the South Fork home. For the three ESA-listed species much of the watershed is designated as critical habitat.
The proposed mining project in the EFSFSR’s headwaters would pose a serious threat to native fish populations. Lower flows, changes in water temperature and the destruction of critical habitat would occur as a result of mining activity at the site, the impacts of which would be felt in perpetuity. Perpetua’s proposal to “restore the river” in reality achieves, at best, the same degraded baseline conditions at the headwaters that are in need of restoration today due to mining activities in the past.
Here are a few takeaways from IRU staff on the impacts of the project on native fish populations:
A mile-long fish tunnel or “fishway” would reroute the river around the existing Yellow Pine pit lake during mining activity. While described in the SDEIS as the “greatest benefit” to chinook and steelhead by restoring access to blocked habitat, the Forest Service writes, “The fishway may be a partial barrier by discouraging migration of some fish, but the extent of this is unknown.”
Perpetua is simply shifting barriers from one site to another. While access to the upper EFSF will be restored, upper Meadow Creek, which is designated as critical habitat for both bull trout and chinook salmon, will be blocked and inundated by millions of pounds of mine waste.
Modeling related to temperature is misleading at best. Stream temps will drop during early mining as Meadow Creek and other streams will be routed through tunnels underground. Temperature increases occur as soon as "reclamation" starts and streams are returned to natural channels and will stay elevated until planted shrubs/trees in riparian areas begin to provide shade. For fish, this means that the initial reduction in temperature is meaningless as there is no real habitat for them to occupy. As soon as the habitat begins to be available, temperatures will increase and may make any new or reclaimed habitat unsuitable.
The 100 year estimate for temperatures to stabilize post-mining is misleading. This area generally consists of poor soil and the project will create a massive growth media deficit. The success of all riparian planting is highly theoretical and temps may never rebound if the tree cover is not established.
Any claims of opening habitat for chinook are dubious at best. The Forest Service states that impacts from this project may temporarily or permanently displace chinook from several mine site streams. Following restoration, there technically be more 'habitat' available but the Forest Service states that, "flows and temperature make the additional habitat less optimal."
For bull trout, they are losing in all aspects. Following closure and reclamation, there will be a “net decrease in both quantity and quality of habitat for bullhead trout and westslope cutthroat trout,” according to the Forest Service.