While the siting of wireless facilities is generally a local matter subject to zoning ordinances and statutes, the FCC has some rules relating to the location and construction of communications towers.  For example, to ensure safe air navigation FCC rules require the registration of towers or other structures that support antennas, such as water towers or buildings, that are more than 200 feet in height or located near an airport runway.  The FCC administers these requirements through the Antenna Structure Registration (ASR) system.  The FCC also administers rules to ensure the construction of communications towers complies with environmental and historic preservation laws, including the National Environmental Policy Act and National Historic Preservation Act.  In addition, the FCC has provided guidance on how long a state or local government has to act on a zoning application.