The drowning of an Oklahoma firefighter and a Texas teenager in storms that swept through the Southwest highlight the persistent dangers posed by storm drains that help protect neighborhoods during flash flooding but can suck in unsuspecting residents and rescue workers. In Claremore, Oklahoma, on Saturday, Fire Capt. Jason Farley was leading a rescue crew that helped evacuate families from flooded duplexes in the Tulsa suburb when he stepped into a water-filled box culvert, said Fire Chief Sean Douglas. In 2002, the National Institute for Occupational Safety and Health recommended that municipalities take steps "to minimize potential for injury" after the death of a Denver firefighter who was swept into a pipe while rescuing a woman stranded in a flood near a water-filled culvert. National public works and engineering groups say the grates can be kept clear with routine maintenance and innovative designs. Ken MacKenzie, a committee co-chair for the National Association of Flood and Stormwater Management Agencies, said new drainage systems are generally safer but cities need to upgrade many older structures that "can get a lot of water depth at the inlet of a pipe" and create dangerous situations.