McDonald Morrissey Associates was founded in 1990 by Michael McDonald and Daniel Morrissey following distinguished careers with the U.S. Geological Survey. From the beginning, MMA was built on a simple premise: complex groundwater problems deserve rigorous science and independent judgment. That founding philosophy still shapes how the firm approaches every project today.
What began as a specialized modeling practice has grown into a nationally recognized consultancy serving industrial, legal, and government clients across the United States and internationally. Along the way, MMA’s principals have contributed to landmark groundwater investigations, water-management disputes, and litigation support engagements — building a reputation for technical credibility that clients and courts alike have come to rely on.
MMA was founded by two U.S. Geological Survey veterans whose research and fieldwork helped define modern groundwater science. Their partnership combined deep technical expertise with a shared commitment to independent, defensible analysis — a combination that remains at the core of MMA’s identity.
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 work fundamentally changed how hydrogeologists study and predict groundwater behavior, and 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, with a focus 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.
The founders’ emphasis on scientific rigor, independence, and clear communication continues to guide every MMA engagement — from routine water-supply evaluations to complex litigation support involving multimillion-dollar disputes.
Today, MMA carries forward the same commitment to quantitative rigor and practical, independent guidance that defined its earliest work — helping clients navigate groundwater decisions with confidence, backed by decades of proven experience.
