Michael Sklash, PhD, P.Eng., is senior hydrogeologist at the Dragun Corp. in Farmington Hills, MI. He has been a full-time consultant with Dragun since 1992, and prior to that, a Professor at the Univ. of Windsor in Windsor, Ontario. Sklash received his degree in geological engineering from the Univ. of Windsor in 1973. He completed his master’s (1975) and doctorate (1978) in earth sciences at the Univ. of Waterloo in Waterloo, Ontario, where he focused on using isotopes to determine the role of groundwater in surface water runoff. While in academia, Sklash published many articles that focus on hydrogeology, the relationship between surface water and groundwater, and isotopes in hydrogeology. In his work with Dragun, he uses a multidisciplinary approach to solve large, complex problems in hydrogeology, often using isotopes such as those discussed in this article, nitrate isotopes for agricultural problems, and others. He has served as an expert witness in groundwater matters in the U.S., Canada, and New Zealand, and has taught about, consulted on, and/or conducted research in many countries, most recently in Malaysia. Sklash is a professional engineer in Ontario.