by Michael Howell
Bitterroot Valley residents are seeing a lot of helicopter activity in the valley right now. Some of it is related to spraying for noxious weeds as the Bitterroot National Forest has been cooperating with the Ravalli County Weed District in treating cheatgrass and spotted knapweed on approximately 3,000 acres through the aerial application of herbicides, with the goal of reducing or even eradicating these species.
Aerial spraying with a helicopter began on September 18 and ended September 29, 2023. Treatment units are located on the Darby-Sula Ranger District in the areas of Sleeping Child, Little Sleeping Child, Gird Creek, and Tolan Ridge.
The U.S. Geological Survey (USGS) has also begun some low-level helicopter flights over a broad region in Idaho and Montana, including the Bitterroot National Forest, to image geology using airborne geophysical technology. The survey work started on September 25 and will be conducted for approximately two months, and then resume in mid- to late-spring of 2024, weather and wildfire restrictions permitting.
According to a press release from the Bitterroot National Forest, flights will cover an area of more than 3,000 square miles and include portions of the following counties: Beaverhead, Custer, Idaho, Lemhi, and Ravalli.
The survey will use an Airbus AS350-B3, or similar, helicopter equipped with an elongated “stinger” mounted to the underside of the cabin extending forward. Instruments in the stinger and inside the cabin will measure variations in the earth’s magnetic field and natural low-level gamma energy created by different rock types.
“The scientific instruments on the helicopter are completely passive with no emissions that pose a risk to humans, animals, or plant life,” states the press release. “No photography or video data will be collected. The data collected will be made freely available to the public once complete. The aircraft will be flown by experienced pilots who are specially trained and approved for low-level flying. The company works with the FAA to ensure flights are safe and in accordance with U.S. law. The surveys will be conducted during daylight hours only.”
According to information released by the USGS, the flights will be based out of Lemhi County Airport. The flights could shift with little warning to other parts of the survey area as necessitated by adverse flying conditions.
The agency states that the purpose of the survey is to provide images that expand the fundamental knowledge of geology underpinning the Idaho Cobalt Belt and the Montana-Idaho Porphyry Belt, two formations that have the potential to host critical minerals like cobalt, niobium, rare earth elements and titanium.
The new geophysical data will be processed to develop high-resolution three-dimensional representations of bedrock composition and structure to depths more than 3,280 feet (1 kilometer) below the surface.
“The 3D models and maps are important for improving our understanding of critical mineral resource potential, water resources, groundwater pathways near legacy mining areas, parameters for infrastructure and land use planning, and potential risks of naturally occurring radon,” according to the press release.
The helicopter will fly along pre-planned flight paths relatively low to the ground at about 300 feet (100 meters) above the surface. The ground clearance will be increased to 1,000 feet (300+ meters) over populated areas and will comply with Federal Aviation Administration (FAA) regulations. Flight line separation will be approximately 200 meters, with 2000 meter tie-line spacing, throughout the survey area.
The USGS is contracting with Dewberry Engineers Inc., who has subcontracted Sander Geophysics Ltd, to collect data.
According to BNF Public Affairs Officer Todd McKay, the Bitterroot National Forest has no further information than the press release sent by the United States Geological Survey about the helicopter survey, such as the flight schedule or whether it flies over the wilderness areas or only over Forest management lands.
One avid hiker in the Bitterroot told the Bitterroot Star, “While it is true that they ‘are completely passive with no emissions that pose a risk to humans, animals, or plant life’—if you are looking for peace and quiet and find yourself underneath one of these surveys as I did on a hike in Lemhi County last fall, the disturbance from the low-flying helicopter completely ruined my all day walk, all day. Of course, this is also an enormous taxpayer subsidy to the mining industry.” The USGS contact person for the press release did not return repeated phone calls last week or this Monday.
The survey fits into a broader effort by the USGS, the Idaho Geological Survey, the Montana Bureau of Mines and Geology and many other state geological surveys and other partners, including private companies, academics and State and Federal agencies to modernize understanding of the nation’s fundamental geologic framework and knowledge of mineral resources. This effort is known as the Earth Mapping Resources Initiative (Earth MRI), and it includes airborne geophysical surveys like this one, geochemical reconnaissance surveys, topographic mapping using LiDAR technology, hyperspectral surveys, and geologic mapping projects.
According to the agency, the motivations for starting the Earth MRI have to do with potential investments. The United States is 100-percent-dependent on imports for 21 critical mineral commodities and is at least 50 percent dependent on imports for another 28 critical mineral commodities. They state that undiscovered deposits of at least some of these critical and strategic minerals almost certainly exist in the United States, “but mineral exploration by the private sector is hampered by the lack of modern geological, geophysical, and topographic data. In contrast, governments of other countries provide such datasets to the public and private sectors and studies in Australia and Canada have reported that investments by their federal governments in these basic geologic and geophysical datasets can be expected to lead to investments five times as large by the private.”
A couple of private companies that may stand to benefit from the government survey are U.S. Critical Materials and Canadian owned U.S. Critical Metals which are currently proposing to mine for rare earth elements (REE) in the headwaters of the Bitterroot River where they own 223 mining claims across seven square miles in the Sheep Creek drainage along the West Fork of the Bitterroot River about 36 miles south of Darby. The company hopes to be operational in about five years with both underground and open-pit mines and nearby ore processing operations.
Rare-earth mining usually involves excavation of ore-bearing earth followed by chemical leaching in on-site ponds, or by pumping leaching chemicals through pipes directly into the ore beds. According to the Harvard International Review, both methods produce toxic waste with high risk of environmental and health hazards.
“For every ton of rare earth produced, the mining process yields 13kg of dust, 9,600-12,000 cubic meters of waste gas, 75 cubic meters of wastewater, and one ton of radioactive residue,” states the report. “This stems from the fact that rare earth element ores have metals that, when mixed with leaching pond chemicals, contaminate air, water, and soil.”
Several local and regional conservation organizations have expressed concerns about the proposal including a newly formed local group called Bitterroot Clean Water Alliance (BCWA) which has sponsored public informational meetings in Stevensville and Hamilton. Spokesperson for BCWA, Dr. Philip Ramsey, states “We are not against mining. It’s just that there are much better places to extract REE than in the pristine headwaters of the Bitterroot River.” He points to the Berkley Pit in Butte as a good example. He said work was already being done to implement a system for extracting REE from the water that now fills the pit. He said it could even be extracted from coal ash which is also in big supply in the state around Colstrip. He is also an expert on how mine wastes affect rivers and soil. He said the toxicity of mine waste and ore processing for REE is a clear danger and poses a threat to wildlife, including the endangered species that inhabit the area such as grizzly bears and bull trout. It also has the potential of polluting the Bitterroot River with radioactive materials.