A 58-year-old man from Ceres was missing as of press deadline, feared dead since disappearing into the water of New Melones Reservoir on Saturday.

Sources in social media say the man is Richard “Rick” Matlock. He jumped into the lake for a swim near the southeast area of the dam but never resurfaced.

Agencies involved in the search include the Tuolumne County Sheriff’s Office and its boating unit, the Tulare County Sheriff’s Office boating unit and the Merced County Sheriff’s Office which brought in sonar and underwater camera equipment.

Tuolumne sheriff’s spokeswoman Sgt. Andrea Benson said that the man who is presumed to have drowned was aboard a Glastron boat with his son-in-law. At approximately 1:30 p.m., the Calaveras Sheriff’s Office received a report that the man jumped in to swim and did not resurface.

“Due to the lack of visibility and depth in the water, which can be up to 400 feet at times, boating units are using the assistance of sonar and remotely operated underwater vehicles for the search,” the Tuolumne County Sheriff’s Department said in a Facebook.

Matlock’s Facebook page says he is from Hughson and graduated from Hughson High School in 1978.