CHICAGO — As Friday marked the official start of summer beach season, the city continues to face a severe, widespread lifeguard shortage that could result in closed beaches and pools later this year. Chicago Park District officials are hoping an added $500 bonus for new seasonal lifeguards will boost a recent recruitment push to fill the 587 lifeguard positions it needs for a full staff. As of May 16, 686 people had applied for the position of lifeguard but none had been hired, according to the Park District. Before they can be hired, lifeguard candidates must earn their certification from the…