American Uranium (ASX:AMU) advances hydrogeological testing at Lo Herma
November 20, 2025American Uranium’s latest update shows meaningful operational progress at its Lo Herma in situ recovery uranium project in Wyoming’s Powder River Basin, with hydrogeological test work now underway alongside the ongoing Phase 1 drilling campaign.
The concurrent programs mark a substantial step towards the next stage of technical evaluation as the company seeks to update its Mineral Resource Estimate and Scoping Study in 2026.
Highlights
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Hydrogeological testing underway to validate aquifer performance.
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Testing program expected to run for approximately two weeks with results due before the end of 2025.
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Phase 1 drilling more than halfway complete with initial results anticipated before year end.
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Current work programs designed to support a Mineral Resource Estimate and Scoping Study update in 2026.
The mobilisation of Petrotek Corporation, a specialist in hydrogeological and subsurface resource assessment with nearly three decades of experience, provides external technical rigour at a time when interest in the project is increasing.
The hydrogeological testing is designed to determine whether the aquifer characteristics at Lo Herma are suitable for in situ recovery methods, which depend on predictable groundwater behaviour, adequate transmissivity and stable wellfield operation.
Petrotek’s program will run parallel to the Phase 1 drilling, reinforcing a structured development path that integrates subsurface data collection with resource growth objectives.
The drilling campaign is already past the halfway point and aims to build on the existing 8.57 million pound uranium resource reported for Lo Herma.
The company expects drilling results and hydrogeological test outcomes before the end of the calendar year, setting the foundation for more detailed engineering and economic assessments in 2026.
A key element of the testing involves step drawdown work, in which single well pumping tests are used to determine well efficiency, sustainable pumping rates and broader hydraulic properties of the mineralised aquifer.
These results will be compared with earlier laboratory permeability tests undertaken on core samples collected during the initial groundwater monitoring well program completed in March 2025.
Each of the four wells drilled in that earlier phase demonstrated submergence of the mineralised sands within the groundwater system, a necessary condition for ISR extraction, and were constructed with five inch casing to accommodate the more advanced pumping and aquifer characterisation now underway.
In commenting on the commencement of both field programs, American Uranium chief executive Bruce Lane said,
“These programs represent major steps toward advancing one of America’s most promising ISR uranium projects. Lo Herma is one of the few near term, low cost ISR projects in the U.S.”
The company notes that future work is expected to include additional monitoring wells and long duration aquifer pumping tests designed to support a mine permit application
Such studies typically form part of the regulatory process for ISR operations in the United States, where environmental, hydrological and engineering data must be integrated into a comprehensive development plan.
While the path to production remains contingent on technical validation and regulatory approvals, American Uranium has now entered a decisive phase in understanding the Lo Herma aquifer system and its suitability for ISR mining.
The combination of drilling progress and hydrogeological testing indicates a project moving through the critical data gathering stages that precede mine design.
With results from both programs expected before year end and a Scoping Study update planned for 2026, Lo Herma is approaching a period of increased clarity in a US market where interest in domestic uranium supply continues to escalate.
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