WOODSTOCK — A heavy downpour overnight caused flash flooding of the Lost River, stranding 84 people at two campgrounds and causing extensive damage to Route 112 (Lost River Hill), according to Police Chief Douglas Moorhead.
Moorhead said a micro-burst of heavy rain that came off one side of the ridge line at Mount Moosilauke hit the town, causing Lost River to rise rapidly and overflow its bank, stranding four people at Maple Haven Campground and another 80 at the Lost River Valley Campground.
He explained that when a storm comes off the mountain, it sometimes can dump four to six inches of water on the area in a very short time.
Moorehead said he hadn't seen Lost River or the Pemigewasset River running as high as they are since Hurricane Irene in 2011 or Hurricane Gloria in 1985.
No one was injured, he said.
As quickly as the Lost River rose, it has quickly receded, he said.
The Lost River campers are now able to walk out, but Moorhead said part of the road near the bridge leading in and out of the campground was washed away. Gravel needs to be brought in to repair it.
He estimated it will be about mid-day before cars and trucks will be able to leave the campground, which expects to be open this weekend.
He urged people to stay out of both the Lost and Pemigewasset rivers for fear they will be swept away in water that continues to run high and fast.
"This will be an emergency situation for a while and people should stay in place and away from the rivers," he said.
Moorhead also said that about a three-mile stretch of Route 112 was damaged and portions were washed out. He said the eastbound lane has "some significant damage" but light traffic is being allowed through.
"I have been police chief for 20 years and have never seen it this bad in that area," he said.
Officials at Lost River Gorge said they saw some flooding, but suffered no structural damage. The popular site will be closed Friday and will reopen on Saturday.
The National Weather Service issued a flood warning for both rivers and extended it until Thursday evening for the Pemigewasset.
At 4 a.m., the weather service said the river was at 9.9 feet, above the 9-foot flood stage. It predicted the river would continue rising to 11.5 feet Thursday morning, but will fall below flood stage by late this afternoon.