Initial results from an investigation into why a dam released a surge of water on the North Shore, that resulted in tragedy, has found human error as one of the main causes. 

Metro Vancouver released preliminary findings into an unexpected release of water from the Cleveland Dam into the Capilano River in North Vancouver on October 1.

"While the review continues, we can now confirm that the clearest contributing factor was human error related to programming of the control system for the spillway gate at the Cleveland Dam," Metro Vancouver commissioner Jerry Dobrovolny stated in a news release. "Metro Vancouver takes responsibility for this mistake and our deepest sympathies go out to those affected by the tragic loss of life."

North Vancouver RCMP stated on October 1 that several people who were fishing at the river at the time were swept away but four of those individuals either swam to shore or were later rescued.

However, one man was later found dead while a second male, identified by news reports as the 27-year-old son of the first man, remains missing.

Dobrovolny said that Metro Vancouver hasn’t experienced any similar unintentional water releases in approximately 20 years.

CBC News reported that four people fishing were trapped on a small island in the river when the water levels abruptly rose in 2002. During that same year, a film crew working near the dam was endangered when a valve controlling the dam’s gate opened by mistake.

Metro Vancouver stated in its news release that these incidents occurred while commissioning a new system, which caused an unplanned high flow release and which had been since remedied.

"Following technical recommendations by experts, Metro Vancouver upgraded the Cleveland Dam spillway gate from a mechanical to fully automated control system in 2002 and there have been subsequent upgrades,” Dobrovolny explained.

To implement new preventative measures, Metro Vancouver is bringing in consultants and peer reviewers for an evaluation of current practices and procedures and recommendations on how to improve operations and maintenance systems.

Potential enhancements being considered include an improved public warning system and increased monitoring downstream of the dam.

In addition, the spillway gate of the dam will remain in the lowered position throughout the winter, with water from the lake flowing from the spillway into the Capilano River.

Metro Vancouver stated that it conducts dam safety reviews every seven years, including evaluating public safety measures. An independent technical expert conducted the last review in 2016, as required by the Provincial Dam Safety Program.

A formal public safety assessment of the Cleveland Dam was completed earlier this year, which considered the nature of the dam and the river system, the geography, and potential hazards for downstream users and activities. 

Water contained by the dam, built in 1954, forms the Capilano reservoir, which provides drinking water in the Lower Mainland.

Metro Vancouver will release further information when available.