Marvin F. Glotfelty Clear Creek Associates Scottsdale, USA Marvin F. Glotfelty is a Principal Hydrogeologist and co-founder of Clear Creek Associates, a hydrogeological consulting firm with offices in Tucson and Phoenix, Arizona. During his 23-year career, Glotfelty has participated in almost every aspect of the hydrogeologic sciences, and he has given over 45 presentations on hydrogeologic and water well topics. He has also authored or co-authored over 20 publications, including NGWA’s Illustrated Glossary of Driller's Terms.