In 2009 the city adopted two ordinances that benefited Hillsboro Airport, owned and operated by the Port of Portland. Ordinance 5925 amended the Hillsboro Comprehensive Plan, creating an Airport Use (AU) zone that allowed a variety of airport-related uses. Ordinance 5926 amended the Hillsboro Zoning Ordinance, creating an Airport Safety and Compatibility Overlay (ASCO) zone. Ordinance 5926, creating the AU zone and ASCO zone, is codified at Hillsboro Zoning Ordinance chapters 135A and 135B.
The ASCO zone is intended to be applied to property within 6,000 feet of the airport, and imposes various limitations on uses and new development within six subzones, depending on proximity to the airport and its runways. In addition, under Ordinance 5926 development in ASCO subzones 2, 3, 4, 5, and 6 was subject to the obligation to provide an avigation easement to the Port of Portland prior to recording land division plats or issuing certificates of occupancy.
Ordinance 5926, Section 135B(C)(6) defines "avigation easement" as:
"A type of easement which conveys the following rights:
" A right to subject the property to noise, vibrations, fumes, dust, and fuel particle emissions associated with normal airport activity.
" A right to prohibit the erection or growth of any structure, tree, or other object that would penetrate the imaginary surfaces as defined in this ordinance.
" A right-of-entry onto the property, with proper advance notice, for the purpose of marking or lighting any structure or other object that penetrates the imaginary surfaces as defined in this ordinance.
" A right to prohibit electrical interference, glare, misleading lights, visual impairments, and other hazards to aircraft flight as defined in this ordinance from being created on the property."