MI HB5638

Amends Michigan's environmental law to revise the process for evaluating water withdrawals of 1,000,000 gallons per day or less from state waters to supply common distribution systems.

Allows property owners to submit hydrological analyses by licensed professionals to challenge zone designations, with the department required to respond within 20 working days (plus up to 5 additional days in specific circumstances).

Property owners can proceed with zone A or B withdrawals after registration; zone C withdrawals require self-certification of implementing water conservation measures and submission of water level recovery measurements within 2 years.

Establishes a site-specific review process for zone B cold-transitional withdrawals or zone C/D withdrawals, with the department completing reviews within 10 working days using actual stream flow data and peer-reviewed models.

Defines technical standards for aquifer performance tests and streamflow depletion calculations, including specific measurement requirements, time intervals, and accepted analytical methods from published hydrogeological research.