Multiple boaters were stranded along the Columbia River late Monday due to low water flows, according to the Clark County Sheriff's Office.
At least four boats were aground at Bachelor Island near the mouth of the Lewis River and five were aground near Government Island across from Vancouver, said sheriff's Deputy Todd Baker.
Dan Smith, 35, of Washougal said he and 20 other people in his party were stranded aground on Oregon's Gary Island across from Reed Island State Park near Camas.
"We came here Friday to go camping for the long weekend," Smith said. "We tried to leave Sunday but were trapped. We were hoping the water would rise, but it's not."
Smith said he called Bonneville Dam to ask about releasing more water.
"They said there was nothing they could do," Smith said.
Baker said all of the boaters were well-supplied or had help that could transport them back to the mainland.
"I came onshore and talked to people to see what their plan was," Baker said. "They said, 'We're going to wait until the water comes up.' Everybody just kind of deals with it."
At noon Saturday, the Columbia at Bonneville Dam was flowing at 161,300 cubic feet per second. By 8 p.m. Monday, the flow was 100,200 cubic feet per second, according to Bonneville Dam statistics.
The low flow was caused by a low tide from the Pacific Ocean and possibly from Bonneville Dam holding back water, though the latter couldn't be verified late Monday, Baker said.
"It's not uncommon to anchor the boat in the water at night and to wake up and find it aground," Baker said.
Baker said some boaters may have had a better chance of getting boats back on the river at high tide Monday. High tide near Vancouver was expected at about 9 p.m., according to the National Oceanic and Atmospheric Administration.
Baker recommended that boaters check tide levels before heading out on the river and anchor out farther from shore when water levels are expected to be low.
He also recommended that boaters buy an annual policy with a boat towing service, such as Columbia River Marine Assistance or Vessel Assist. Calling 911 won't help, as emergency responders will only respond if a vessel is in distress, Baker said.
"It costs $100 or less per year," Baker said. "It's like the AAA on the river. It's a must for boaters."
It costs about $200 per hour to tow a boat without a towing service, he said.