MD SB42

Department of the Environment must designate four specific watersheds and all their headwaters and tributaries as interjurisdictional flood hazard watersheds: Carroll Creek (Frederick City/County), Gwynns Falls (Baltimore City/County), Jones Falls (Baltimore City/County), and Herring Run (Baltimore City/County)

Adds new statutory definitions for "headwater stream" (source of a stream or small stream/wetland at the highest end of a watershed) and "interjurisdictional watershed" (land spanning two or more jurisdictions draining to a common outlet)

Flood management plans for interjurisdictional watersheds are subject to review and approval by the Department as one unified plan across all affected subdivisions

Effective date is October 1, 2025