Black Hawk County, IA Environmental Rules: Stormwater Management (2026)

Black Hawk County's subdivision design standards, adopted under Title 17, place drainage control on the developer rather than leaving it to individual lot owners. 020(B)(10)(b) requires a stormwater or drainage easement wherever a proposed subdivision is traversed by a watercourse, channel, drainageway or stream; that easement must be sized to the anticipated drainage but never less than 30 feet wide, and it has to be shown on the recorded plat, alongside the separate 10-foot utility easements the same subsection requires along rear or side lot lines.

050(C) sets three concrete storm drainage duties: adequate storm sewers and inlets must be provided wherever necessary, natural waterways within the subdivision must be maintained and protected rather than filled or rerouted informally, and every stormwater facility, from a culvert to a detention basin, needs sign-off from both the County Engineer and the Board of Supervisors before it counts as compliant. These stormwater requirements sit alongside the chapter's street standards, which route paved streets using open ditches for drainage into a minimum 24-foot surfaced width with a three-foot rock shoulder, and streets using curb and gutter into a 31-foot back-to-back minimum, so the street cross section and the drainage system are engineered together rather than as separate approvals.

The rule applies only to subdivisions platted in the unincorporated county; subdivisions inside Waterloo, Cedar Falls or the county's other incorporated cities are reviewed under those cities' own subdivision and stormwater ordinances, not BHCC Title 17.