A former Vancouver lifeguard has been charged for allegedly sexually assaulting four boys in a series of incidents dating back four decades.

Abraham Kiewiet, 70, is charged with five counts of indecent assault on a male and five counts of gross indecency.

Police allege he assaulted four boys between the ages of 11 and 17 between 1971 and 1982 when he worked for the city's Park Board, instructed at the Vancouver Lifeguard School and volunteered as a YMCA aquatics coach.

The alleged victims are now in their 40's and 50's, and investigators believe there are other victims and are asking them to come forward.

Kiewiet was arrested at his home and released on a promise to appear next month and under the condition that he not be found in any public place where children might be, and not to seek work that would put him in a position of trust with children.