Update 3:00 p.m. Saturday: Montgomery County Fire and Rescue has ended their search operation for the missing WSSC employee.
All resources are being pulled out of the area except for Maryland Natural Resources Police who will remain until dark.
The adult male victim has not yet been located.
Authorities search for missing WSSC staffer
The Washington Suburban Sanitary Commission has concluded its search for a missing employee for the night, planning to restart Saturday at 9 a.m.
The man has been missing for several hours at the Triadelphia Watershed in Montgomery County. Authorities searched thousand heavily wooded acres.
"We're very concerned about out missing employee and doing everything we can to find him," WSSC General Manager Jerry Johnson said in a statement. It said more than 200 people from WSSC police, Montgomery County Fire Rescue, Howard County, State police and Park Police mounted units are involved in the search.
Dogs, boats, night vision equipment and a helicopter are involved in searching the heavily wooded area and the water, the statement said. Officials had originally planned to call off the search by 7:30 p.m. Friday because of darkness, but continued for another hour and a half. A boat was found, but it's unclear whether it belongs to the missing man.
"We also have vehicles with flashing lights at ramps to guide our employee in case he is disoriented," Johnson said.
WSSC is not releasing the name of the missing man, it said.