The Mercer Island Police Department (MIPD) Marine Patrol unit was part of an immense rescue response in search of a missing man in Lake Washington on the late afternoon of July 30.

A 61-year-old man from Nevada was not found as of this writing after disappearing under water about a nautical half mile to a mile northwest of Mercer Island. A rescue wasn’t possible at that time in the approximately 170 feet of water where the man disappeared, according to the MIPD, which noted that its two-member unit was dispatched to the scene at about 4:20 p.m.

The investigation and recovery phases of the incident are ongoing.

MIPD Marine Patrol unit’s Chad Schumacher said they believe alcohol may have been a factor in the incident.

According to an MIPD press release, the caller — a 51-year-old Seattle area resident — said his uncle wasn’t wearing a lifejacket when he jumped into the water while the boat was moving. When the nephew drove the boat back to retrieve his uncle, he wouldn’t get into the boat and kept pushing away from the vessel.

“After several minutes of trying to get his uncle into the boat, his uncle failed to return to the surface,” MIPD reported.

There were a few other boats in the area, but no other witnesses to the incident, said Schumacher, adding that King County Sheriff’s Marine Rescue Dive Unit and Seattle Harbor Patrol offered assistance. Along with some Eastside fire units, members of the Bellevue and Medina police departments raced near the scene to help, but the incident was too far off the coast for them to assist.

Schumacher said none of the units entered the water at the time of the incident because of the depth where the man disappeared.

“We’re waiting for some specialized equipment to do a search for the gentleman,” said Schumacher, adding that they’re working with the family and hoping to conduct a search this week with Redmond’s Strategic Robotic Systems’ remote operated vehicle (ROV) that features imaging sonars. They’re currently waiting to see if the company is available to aid with the search this week.

On June 17, the company utilized its ROV to help Mercer Island police recover a Bellevue man who drowned in Lake Washington in the Meydenbauer Bay area.

Members of the Mercer Island Marine Patrol and Bellevue emergency responders searched for the man on the evening of June 16 after he jumped into the lake to try and assist his young son who fell off their motorboat, according to the MIPD.