McHenry County, IL Landscaping Rules: Rainwater Harvesting (2026)

McHenry County's Stormwater Management Ordinance (Ch. 17.60, adopted by Ord. O-2020-09-15) does not require unincorporated property owners to obtain a stormwater management permit before installing a rain barrel, cistern, or rain garden for landscaping. Section 17.60.020(C)(1)(e) exempts "gardening and landscaping that does not involve filling, grading, or the construction of berms" from the ordinance's permit requirements entirely, so a homeowner catching roof runoff in a barrel or buried cistern for garden irrigation never triggers the Enforcement Officer review that larger regulated development faces.

The ordinance's definitions appendix, § 17.60.270, formally recognizes rain barrels and cisterns as "green infrastructure," the same category as green roofs, rain gardens, and vegetated swales, defined as any technique that "reduces runoff volume through preserving, restoring, utilizing, or enhancing the processes of infiltration, evapotranspiration, and reuse." That classification matters for larger sites: under § 17.60.060(B)(7)(a)(1), any regulated development creating new impervious area must provide water quality treatment, and the code lets an applicant satisfy that using "existing or proposed best management practices or green infrastructure methods specifically designed for water quality treatment," meaning a builder can count rain barrels or cisterns toward the same standard a detention pond or hydrodynamic separator meets.

McHenry County sits over a sole-source aquifer, and the ordinance's stated purpose at § 17.60.010(C)(1)(h) is in part to "protect the quantity and quality of groundwater resources." The McHenry County Stormwater Commission (MCSC) and, within their own borders, each Certified Community administer the ordinance; a property owner outside those municipal boundaries answers to MCSC staff directly if a project is ever questioned.