Toby J. Hewitt, P.G.
Senior Hydrogeologist



Mr. Hewitt, a senior hydrogeologist with over 15 years of experience in water resources, recently joined Hydro Geo Chem. His experience includes working at an in-situ recovery uranium mine as a project geologist mapping and evaluating uranium ore fronts for in-situ mining. He worked on an underground coal gasification R&D permitting project in central Wyoming’s Powder River Basin; has managed the restoration division at Smith Ranch-Highland Operations Uranium Mine; managed an environmental consulting firms Gillette, Wyoming field office, providing hydrologic technical support to clients in the Powder River Basin. His areas of expertise are in aquifer characterization; aquifer testing and analysis; hydrogeologic conceptual models; groundwater surface water interaction; geologic cross-sections; groundwater flow mapping; well design, construction, and development; and numerical and analytical groundwater modeling.


M.S. (Geology), University of Montana, 2004
B.S. (Geology), University of Hawaii-Hilo, 2000


Professional Geologist, Wyoming, License Number PG-3625, 2007
40 Hour HAZWOPER, 2015
29 CFR 1910.120(e), MSHA New Miner, 2013

Representative Experience

Water Resources:

Basin 42C Water Right Records Research Summary Report: Final report submitted to the BLM reporting on the results of water right records research on BLM claims that were missing flow rate or volume data. Records in the Miles City Field Office were reviewed and scanned to provide flow rate and volume data for the DNRC.

King Mine Expansion Spring and Seep Survey: Conducted an extensive field survey and geologic mapping of the perimeter area of a proposed underground coal mine expansion. Field work for the survey resulted in locating one seep and a water quality monitoring station was established at the site.

Paris Hills Proposed Phosphate Mine, Hydrogeological Characterization: Performed oversight of a large production water well build and well development. Aquifer test and analytical analysis of aquifer properties were used to develop a regional numerical groundwater flow model.

Sevier Lake Project Trench Test Groundwater Flow Model: Designed a three-dimensional numerical groundwater flow model to develop reliable estimates of hydraulic conductivity and specific storage for use as input values to the groundwater flow model that was being developed for a prefeasibility study.

Draft East Wintinna and Weedina Coalfield Hydrology Review: A draft summary of documents reviewed for the East Wintinna and Weedina Coalfields. The review summarizes information regarding geology of the areas, extract basic hydrogeologic information into tables and summary paragraphs, document the sources of the information, review the data quality and analysis, and summarize the thicknesses and depths of hydrostratigraphic units. The intent is to compile the information to facilitate analysis of how hydrogeologic conditions may impact potential underground coal mining operations at East Wintinna and Weedina coalfields, and to assist in identifying potential impacts to availability and quality of the groundwater system due to mining operations.

Underground Coal Gasification Research and Development Permit Application-Hydrogeologic Site Characterization, Powder River Basin, Wyoming: Performed aquifer testing in three aquifers in support of the aquifer characterization section of the demonstration project and characterized the planned location of the gasifier. Analytical models were designed to estimate operational water usage and disposal volumes.

Mine Unit K-North Hydrologic Test Report, Smith Ranch-Highland Uranium Project, Wyoming: Planned and implemented the aquifer testing program for a mine unit expansion prior to the start of production. The aquifer tests were submitted with a wellfield data package to the Wyoming Department of Environmental Quality.

Fortification Creek Aquifer Testing and Simulation of Discharge for Reservoir Design, Wyoming: Conducted aquifer testing and analysis for water production estimates from three coal seams in the Powder River Basin. A numerical groundwater flow model was designed to predict discharge volumes in support of a reservoir design.

Piceance Creek Oil Shale Project, Colorado: Conducted numerous pumping tests, groundwater sampling, injection-falloff testing, spring and seep base flow investigation, and surface water characterization.

Geoduck Land & Cattle Company Water Right Change Application, Montana: Conducted an intermediate to local groundwater flow system investigation on the timing of return flow from flood irrigation water to the surfaces water source (Beaverhead River). The client switched from flood irrigation to center pivot sprinkler irrigation to conserve water and expand irrigable lands. The study was in support of a change application to prove no adverse impact to downstream water users. Shallow monitor wells and staff gauges were installed along seven miles of the Beaverhead River and monitored throughout the irrigation season. Flow measurements were conducted on the river, tributary sloughs, creeks and irrigation ditches along the reach. Slug tests and pumping tests were conducted to obtain aquifer properties for a numerical groundwater flow model.

Geoduck Land & Cattle Company New Groundwater Appropriations Application, Montana: A new groundwater water right permit application was submitted to the Montana Department of Natural Resources and Conservation. The permit included a 3-day pumping test to determine groundwater - surface water connectivity, groundwater availability and aquifer parameters. Several monitor wells, and staff gauges were monitored during the aquifer test. The permit included proving groundwater availability and no adverse impact to other groundwater or surface water users.

Groundwater Restoration:

Willow Creek In-Situ Uranium Project Restoration Plan, Powder River Basin, Wyoming: Designed an analytical model to predict flow volumes for disposal during the groundwater sweep phase of restoration.

Mine Unit C Restoration-Bioremediation Project Final Report, Smith Ranch-Highland Uranium Project, Wyoming: Conducted an experimental bioremediation test to restore groundwater at an in-situ recovery uranium mine.

Wellfield 1 Restoration Plan, Smith Ranch-Highland Uranium Project, Wyoming: Designed analytical and numerical groundwater flow models to plan groundwater restoration at in-situ recovery uranium mine. Models were used to predict groundwater flow paths and disposal volumes for various phases of restoration.

Gillette, Wyoming Landfill Groundwater Sampling Project: Conducted semi-annual groundwater sampling at the Gillette area landfills using bailers. Provided cost estimates and plans for installation of low flow bladder pumps in place of using bailers.


Hewitt, Tobias J., "Characterization of impacts to water resources of Upper Miller Creek from septic system effluent, Missoula County, Montana" (2004). Graduate Student Theses, Dissertations, & Professional Papers. 1781.

Hewitt, Tobias J., 2000, Magnesioferrite Formation within Lava Tubes, Undergraduate Fellowship Reports, pp. 30-35. Hawaii Space Grant College, Honolulu, HI



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