American Rare Earths (ASX:ARR) has installed groundwater monitoring wells at the Cowboy State Mine, part of the Halleck Creek Rare Earths Project in Wyoming, US.
The company says quarterly groundwater sampling and analysis will continue throughout the 12-month monitoring period with the completion of 24-hour pump tests to support groundwater modelling.
A formal mine permit application is also expected to be submitted in parallel to data collection.
The Cowboy State Mine Prefeasibility Study (PFS) is progressing on schedule for delivery in late 2025 and American Rare Earths “remains focused on advancing one of the largest and most strategically significant rare earth projects in the United States, supporting the nation’s efforts to develop a secure, sustainable critical minerals supply chain”.
The company says this represents a significant step forward in the environmental permitting process with the Wyoming Department of Environmental Quality (WDEQ), a requirement for progressing the company’s state mining permit application.

Water quality collection methods and analysis are being conducted in accordance with guidelines defined by the WDEQ.
CEO Chris Gibbs says the installation of the groundwater monitoring wells is an important milestone in the Cowboy State Mine permitting pathway.
“This work underpins our environmental approvals process and further validates our strategy of developing on state land, which is a major competitive advantage in the US market. We remain on track to complete the Prefeasibility Study by the end of 2025, as we continue to build momentum toward our target of first production as early as 2029,” Gibbs says.
Located on State-managed land, American Rare Earths says the Cowboy State Mine benefits from a significantly simplified permitting framework compared to projects on Federal lands.
The groundwater wells will now be monitored for a full year to generate required baseline hydrological and environmental data. This data will inform groundwater modelling, mine planning, and ultimately support the formal submission of the mining permit application.
Planning is also underway for 24-hour pump testing, which is a key requirement for permit approval. The testing will measure water flow, aquifer connectivity, and potential mine dewatering needs.
American Rare Earths is a critical minerals company advancing the Halleck Creek Project in Wyoming, which it touts as a rare earth deposit with the potential to secure America’s critical mineral independence for generations.
Located on Wyoming State land, the Cowboy State Mine within Halleck Creek “offers cost-efficient open-pit mining methods and benefits from streamlined permitting processes in this mining-friendly state”.
Write to Adam Orlando at Mining.com.au
Images: American Rare Earths



