Ozarka, the Rule of Capture and Hydrogeology:
Untold Story of the Supreme Court Case

Michael R. Thornhill
Thornhill Group, Inc. (TGI)

Details: Mr. Thornhill will present the hydrogeologic setting of Ozarka's Roher Spring. Due to the legal process, the technical facts of this landmark case were never argued (at least formally). Mr. Thornhill, Ozarka's expert hydrogeologic witness in the case and current consultant, will provide evidence demonstrating that Ozarka's production did not adversely impact wells on neighbors' properties. Even so, the case has spawned intense debate with respect to ground-water policy in Texas, and probably was the impetus for the formation of numerous ground-water conservation districts, including the Neches and Trinity Valleys Groundwater Conservation District. Based on Ozarka's average production of 147 gallons per minute, he will discuss how the rules of the district impact other water suppliers more significantly than they do Ozarka.

Mr. Thornhill is the founder and president of Thornhill Group, Inc. (TGI), an independent consulting firm consisting of geologists and hydrogeologists specializing in ground-water resources. Mr. Thornhill has been a consultant in the Austin area since 1989 and formed TGI in 1998. He has provided consulting services in numerous projects across Texas and in several other states. Clients have included municipalities, water supply corporations, municipal utility districts, law firms, engineering firms, developers, water marketing companies, industries, mines and quarries, bottled-water companies, ground-water conservation districts and private landowners.

Mr. Thornhill received his B.S. in Geology (1985) and M.S. in Geology (1990) with an emphasis in hydrogeology from Oklahoma State University, where he studied under Dr. Wayne Pettyjohn. He is a Licensed P.G. in Texas, and a Certified Professional Geologist with the American Institute of Professional Geologists. He has provided presentations to professional groups including the American Institute of Hydrology, the American Association of Professional Geologists, and the Continuing Legal Education (CLE) International. He co-authored with Dr. Charles Woodruff the article entitled Hydrogeology and Karst of a New Town: Case Study of Sun City-Georgetown, Williamson County, Texas" included in Austin Geological Society Guidebook 16, Urban Karst: Geologic Excursions in Travis and Williamson Counties, Texas.