Kiiza Mupendo died as a result of accidental fresh-water drowning, officials said.
The boy was swimming in the lake on Sunday afternoon as part of an Everett church outing, police said. Witnesses called 911 when the boy went missing in the water.
Monroe firefighters found him, performed CPR and rushed him to a local hospital.
He later was taken to Seattle Children's Hospital, where he died just after midnight Tuesday.
It was the second known drowning death of a child in Snohomish County this summer.
Jeremiah Monroe Jr., 12, of Everett, died Aug. 8 after being pulled from Martha Lake near Mill Creek several days before.
More Local News Headlines
Oso Community Chapel celebrates 100th birthday with a makeover App allows Everett parents to track where student's school bus is Two men indicted on drug charges after 11 pounds of heroin found Ferry launches rescue of woman diving at Mukilteo Lake Stevens woman, whom teen rescued from fire, charged with arson Man who smoked meth with baby in car in Edmonds may avoid prison Lake Stevens schools want public input on expansion choices National crime syndicate theft ring suspect arrested in Mill Creek
Our new comment system is not supported in IE 7. Please upgrade your browser here.