"This Advisory Circular (AC) provides guidance to assist airport operators in preparing for water rescue operations.[...]The Federal Aviation Administration (FAA) recommends the guidelines and standards in this AC for the operation of civil airports where aeronautical activity is conducted near a significant body of water. In general, use of this AC is not mandatory. However, this AC provides guidance in meeting the requirements outlined in Title 14 Code of Federal Regulations (CFR) §139.325, Airport Emergency Plan. An airport operator may elect to follow an alternative method, provided it is also found by the FAA to be an acceptable means of complying with 14 CFR part 139, Certification of Airports. For airports certificated under part 139 the use of the guidelines and standards in this AC is mandatory. In the event of a conflict, the requirements under 14 CFR part 139 takes precedence over the guidelines set forth in this AC. The standards contained in this AC must be used for the development of new Airport Water Rescue Plans and are to be implemented at all part 139 certificated airports no later than one year from the effective date of this AC. In addition to the foregoing, the use of this AC is mandatory for all projects funded with federal grant monies through the Airport Improvement Program (AIP) and with revenue from the Passenger Facility Charges (PFC) Program."
United States Federal Aviation Administration: http://www.faa.gov