How Lo Herma’s Pump Tests Unlock ISR Uranium Potential in Wyoming
American Uranium's recent hydrogeological pump tests at the Lo Herma project validate key aquifer properties consistent with nearby operating ISR uranium mines, supporting upcoming resource and scoping study updates.
- Pump tests confirm aquifer transmissivity and hydraulic conductivity align with permitted ISR mines
- Extraction wells sustain 20 gallons per minute flow rates as assumed in Scoping Study
- Results de-risk Lo Herma project ahead of Mineral Resource Estimate update this quarter
- Further regional hydrogeological studies planned to support permitting and wellfield design
- Expansion drilling extends uranium mineralised trends by 3km north of key mine units
Hydrogeological Validation at Lo Herma
American Uranium Limited (ASX – AMU) has taken a significant step forward in advancing its flagship Lo Herma in-situ recovery (ISR) uranium project in Wyoming’s Powder River Basin. The company announced that hydrogeological pump tests conducted by Petrotek Corporation in November 2025 have confirmed that the aquifer properties at Lo Herma are consistent with those of other permitted and operating ISR uranium mines in the region.
The tests demonstrated that groundwater extraction wells at Lo Herma can sustain flow rates of approximately 20 gallons per minute (gpm), a key assumption underpinning the project’s Scoping Study. This empirical evidence of aquifer transmissivity and hydraulic conductivity materially de-risks the project by confirming that the uranium-bearing host sands possess favourable hydrogeological characteristics for ISR mining.
Technical Insights and Test Results
Four monitoring wells were tested, with transmissivity values ranging from 65 to 285 square feet per day and hydraulic conductivity between 1.4 and 8.6 feet per day across different wells. These figures align well with benchmarks from nearby ISR operations, reinforcing confidence in Lo Herma’s production potential. The pump tests included both step-rate and constant-rate methodologies, with sustained pumping over four hours confirming stable extraction rates and minimal aquifer drawdown.
Bruce Lane, AMU’s CEO, highlighted that these results "materially strengthen Lo Herma’s ISR development credentials". He also noted the recent expansion drilling program extended uranium mineralised trends by an additional 3 kilometres north of the existing mine units, which could further enhance the resource base.
Next Steps and Project Outlook
While the pump tests have validated key hydrogeological parameters, Petrotek recommends further work to develop a regional hydrogeologic conceptual model. This will map the distribution of mining sands and confining layers more precisely, essential for detailed wellfield design and regulatory permitting. Longer duration regional pump tests are also planned to assess aquifer confinement and support compliance with Wyoming Department of Environmental Quality requirements.
American Uranium aims to leverage these findings in its Mineral Resource Estimate update scheduled for this quarter, followed by an updated Scoping Study in the second half of 2026. These milestones will provide a clearer picture of the project’s scale and economic viability, potentially attracting further investor interest.
Overall, the hydrogeological testing results represent a pivotal technical validation for Lo Herma, positioning it well within the competitive landscape of ISR uranium projects in the Powder River Basin.
Bottom Line?
Lo Herma’s validated hydrogeology sets the stage for resource growth and regulatory progress in 2026.
Questions in the middle?
- How will expanded drilling results impact the confidence and size of the Mineral Resource Estimate?
- What timeline and challenges lie ahead for securing ISR mining permits based on upcoming hydrogeological studies?
- How might uranium market conditions influence the commercial development strategy for Lo Herma?
