(a) A permanent employee of a county having a population in excess of 500,000 whose principal duties consist of active protection, rescue, and rendition of aid or assistance to persons injured or imperiled in water areas at beaches and lakes, streams, dams, reservoirs, or other bodies of open water (not including swimming pools) or in small craft or airplanes at sea near the shoreline and the recovery from water areas of submerged objects and bodies of persons drowned or believed to have drowned in those areas, or the immediate supervision thereof, including persons employed to perform the duties now performed under the titles of director of beaches, assistant director of beaches, deputy director of beaches, chief lifeguard, assistant chief lifeguard, captain lifeguards, lieutenant rescue boat, lieutenant lifeguards, beach lifeguard, but who performs additional duties, some of which (including the maintenance of peace and order and the apprehension of law violators) are customarily performed by police or peace officers, and whose other duties (such as resuscitation work involving the use of special equipment in cases having no connection with their principal duties) which in other areas are customarily performed by firemen, and other and further duties (such as the rescue of persons from disabled aircraft and small boats in inshore or inland waters and the removal of dangerous obstructions from waters) which do not come directly within any of the aforesaid classifications but are essential to the safety and security of the public, excluding those whose principal duties are those of a telephone operator, clerk, stenographer, machinist, mechanic, or otherwise clearly do not fall within the scope of active lifeguarding or lifesaving service, even though a person is subject to occasional call, or is occasionally called upon, to perform duties within the scope of active lifeguarding or lifesaving service, shall be considered and is hereby classified as an employee whose principal duties consist in "active law enforcement." Persons employed to perform the duties of director of beaches, assistant director of beaches, or deputy director of beaches shall not be within the classification of "active law enforcement" employee, unless those persons have previously been included within that classification, or have performed duties which would have qualified such person as an "active law enforcement" employee under this section.