Flooding from the Arkansas River has left some parts of Bent's Old Fort National Historic Site underwater, as this photo from Tuesday shows/NPS, Rick Wallner

Editor's note: This updates with flooding reports from Fort Laramie National Historic Site in Wyoming, Lake Meredith National Recreation Area in Texas, and Chickasaw National Recreation Area in Oklahoma.

Unusually heavy and persistent spring rains have flooded several units of the National Park System in Colorado, Oklahoma, Texas, and Wyoming, leading to washed out trails, closed campgrounds, and at least one death.

At Lake Meredith National Recreation Area in Texas, a 3-year-old boy in a safety seat strapped into an ORV drowned Sunday when the vehicle became stuck on a sandbar in the Rosita area and then was washed away by high flows of the Canadian River. The ORV was found in 20 feet of water, according to the sheriff's department.

Floodwaters have limited access, but not closed, the grounds of Bent's Old Fort National Historic Site in Colorado.

According to Rick Wallner, the park's chief of interpretation and visitor services, the site that recounts the fur trade of the mid-1800s, was closed Friday-Sunday during the Memorial Day Weekend, primarily because of road access. While the six-mile stretch of Colorado 194 between La Junta, Colorado, and the fort was open, the road from Las Animas, Colorado, to the fort was inundated by high water from the Arkansas River.  The river has been over flood stage for more than a week, and it has rained almost daily.

The flooding hasn't damaged any of the fort facilities, but three-quarters of the park's 1.5-mile loop hiking trail (from the fort south along the river and back) has under water from the Arkansas River

"The river is outside its banks in the park and flowing across it," Chief Wallner said Wednesday.

The flood waters are within 200 feet of the fort, but the fort itself is not flooded or damaged.

"The park itself is pretty waterlogged," the park official said. "We're noticing the mosquitoes already."

Across the nearly 800-acre site are lots of of puddles and standing water, and areas like "large standing lakes" along the road from La Junta, he said.

At Fort Laramie National Historic Site in Wyoming, Superintendent Tom Baker said the Laramie River was predicted to reach a record 9.6 feet above flood stage. However, the flow knocked out a USGS river gauge two days ago, making it impossible to gain an accurate reading of the flood level.

While the park remains open, the lower picnic area was under 3 feet of water and closed Wednesday, the Confluence Trail (confluence of Laramie and N. Platte rivers) was closed, and sandbags had been placed around the 1866 guard house in a bid to keep it from being flooded.

Gray Rocks Reservoir above Fort Laramie was releasing more than 4,600 cfs of water, some of which was flowing over the dam's top. Superintendent Baker said the Laramie River's flow at the park was running about 4,500 cfs, which is close to eight times normal flow (574 cfs) for this time of year.

In Oklahoma, officials at Chickasaw National Recreation Area reported that floodwaters spawned by more than 17 inches of rain the past two weeks had forced closure of the Buckhorn camping area due to concerns for the sewer and electrical systems to function safely, and all boat launches in Lake of the Arbuckles were closed. The only boat launch open in park was on smaller Veterans Lake. Also closed were Catfish Bottoms, Blackjack Road, Eagle Bay, Point Day Use Area, East Hunting Area, and Blue Stem Prairie.

Lake of the Arbuckles was reported to be 13.5 feet above normal for this time of year, officials said.