McDonald Morrissey Associates (MMA) was founded in 1990 by Michael “Mike” McDonald and Daniel “Dan” Morrissey. Before co-founding MMA, Mike spent more than 20 years working as a hydrologist for the U.S. Geological Survey (USGS) at offices in Maryland, New Jersey, Michigan and at USGS headquarters in Reston, Virginia. He served as the Groundwater Specialist for the northeastern region of the USGS, and he developed the groundwater model MODFLOW – the most widely used groundwater model in the world. Prior to founding MMA, Dan worked for the USGS in Utah, Maine and New England, where he served as Chief of the New Hampshire/Vermont District of the Water Resources Division of the U. S. Geological Survey.
MMA is nationally recognized for expertise in the analysis of complex groundwater flow systems for industrial and government clients. MMA principals share more than 100 years of experience in the conduct, management and technical oversight of a wide variety of groundwater projects. MMA’s project experience includes: groundwater resource management and development; wellhead and source-water protection area delineation; mine dewatering; solute transport assessment; remedial design support; plume allocation; expert testimony and negotiation support; and regional groundwater flow assessment.
MMA staff are members of the National Ground Water Association, American Water Works Association, Geological Society of America, American Geophysical Union, and the International Association of Hydrologists.
Michael McDonald, Co-Founder
Mike McDonald spent his early career with the USGS, where he developed MODFLOW — now the world’s most widely used groundwater modeling code and the foundation of modern groundwater simulation. His continued involvement ensures MMA’s modeling work reflects the most current, technically sound methods available.
Daniel Morrissey, Co-Founder
Daniel Morrissey brought complementary expertise from his own USGS career, focused on applying rigorous hydrogeologic analysis to real-world water-resource and contamination challenges. Together, McDonald and Morrissey built a firm centered on translating complex science into practical, defensible answers for clients facing high-stakes groundwater decisions.
That same commitment to technical rigor, independence, and clear communication continues to guide every MMA engagement today.
