Polk County, IA Outdoor Lighting: Dark Sky Rules (2026)

Article 12, Division 1, Section 4 of the Polk County Zoning Ordinance, Exterior Lighting Options, requires every fixture to fall into one of three defined categories: no cutoff, total cutoff up to ninety degrees, or total cutoff at an angle less than ninety degrees, each meeting a separate table of standards. Under Table 12.1, a no-cutoff fixture, one with no shielding at all, is capped at 0.20 footcandles and 10 feet in height for all residential uses and for nonresidential uses in the AG, AT, ER, MU, GC, NB and MH districts, rising only to 0.20 footcandles and 15 feet, or 0.30 footcandles and 20 feet in the Light and Heavy Industrial districts.

Table 12.2 rewards partial shielding: a fixture with total cutoff up to ninety degrees, meaning it must emit maximum candlepower at an angle not exceeding seventy-five degrees from a line perpendicular to the ground, is allowed up to 0.30 footcandles and 15 feet for residential uses, climbing to 1.50 footcandles and 35 feet for nonresidential uses in Light and Heavy Industrial districts. Table 12.3 rewards the most complete shielding: a fixture with total cutoff at an angle less than ninety degrees, where the bare bulb is fully hidden from a five-foot-tall observer standing where the cutoff angle meets the ground, can reach 4.00 footcandles and 50 feet in Light and Heavy Industrial districts, because the design keeps the light source itself invisible off-site.

Every category still caps lighting adjacent to residential zoning at 0.2 footcandles at the property line. Ball diamonds, playing fields and tennis courts can seek an exemption from the Board of Adjustment under Division 2 if fixtures stay under an 80-foot post height and shielding keeps spill-over at the bufferyard line to 0.2 footcandles or less.