"He then approached the boy but could not see him," the report said. "Almost immediately a young teenager lifted the boy out of the water and he appeared to be unconscious.
"After about 12 compressions, the boy coughed up some water but did not seem to be breathing. After another five or 10 compressions he coughed up more water, after another five or 10 compressions he started to breathe."
The boy was given oxygen and kept warm until the ambulance arrived, when the boy's caregiver was first seen.
The centre manager and lifeguard later visited the boy in hospital and found he "seemed to be recovering well".
Council leisure manager Rob McGee said no further action was taken and the lifeguard was still working at the pool.
"All our systems and procedures were found to be fine. All lifeguards are encouraged to keep their eye on the water at all times but they also have to respond to queries from the public."
After the incident, reception staff had been told to remind customers about rules for supervising under 8-year-olds at pools, more poolside radios would be introduced and lifeguard ratios at different areas of the venue could be changed by the lead guard when needed.
The incident was the most serious at council-run pools last year.
Documents obtained under the Official Information Act show 13 near-misses were recorded last year. Most involved children, including a girl who was rescued with a pole after she started drowning in the Moana-Nui-a Kiwa Pool and a 6-year-old boy who became unconscious in the deep end of the Lloyd Elsmore Park Pool. The boy was being watched by his grandfather when he went limp and began sinking.
Another swimmer brought the boy, who was unconscious but breathing, to the edge of the pool and he was treated by ambulance officers.
Auckland Council manages the largest publicly-owned pool network in Australia and New Zealand. Its 24 public swimming pools generate more than nine million visits a year, McGee said.
All pools were Pool Safe-accredited, a standard regulated by the New Zealand Recreation Association and Water Safety New Zealand, and major incidents were investigated.