McCracken County, KY Environmental Rules: Stormwater Management (2026)

Section 150.087, STORM WATER CONVEYANCE AND MANAGEMENT FACILITIES REQUIRED, applies countywide outside Paducah: all development occurring within the county shall provide for properly sized storm water conveyance facilities and shall contain on-site, or provide off-site, storm water management facilities capable of controlling increased runoff relative to its predeveloped condition. No final subdivision plat can be approved, and no permit issued, without a storm water plan or an approved waiver. Section 150.088 then fixes the design storm for conveyance facilities at a 25-year event for open channels and roadside ditches, storm sewers and inlets, and entrance pipes and cross drains alike, while capping the maximum headwater under a 100-year storm so it is not allowed to overtop roads or increase flooding potential in the affected areas.

Section 150.090 governs the management facilities themselves: they must be sized to the difference between pre- and post-development runoff for a 25-year, 24-hour storm, the 100-year storm's effect must be documented, and any detention basin sited in a parking lot cannot be designed to hold water more than six inches deep. Section 150.092 exempts small projects, such as subdivisions with five lots or fewer and no new streets, residential lots over two acres, and nonresidential sites with less than 10,000 square feet of impervious surface, though the Planning Commission may also waive requirements case by case. Section 150.093 requires a professional civil engineer to stamp every design, following the Kentucky Department of Highways drainage manual.