American Rivers, a Washington-based nonprofit, highlighted both the Mississippi River and Ozark National Scenic Riverways with its yearly list of the 10 most endangered rivers in the nation. Other Midwestern rivers to make the list include the Chicago River in Illinois and the St. Croix River in Minnesota and Wisconsin.

The Mississippi has made the American Rivers list eight times since the program's inception. This time its inclusion was as a unique mention that fell outside the top 10.

"We actually did a special nomination and designation due to the recent flooding. We thought it was critical to include this in the 10 endangered rivers, so we now have 11," said Shana Udvardy, the group's director of flood management policy. "This was due to the threat of outdated flood management and an overreliance on levees as a flood-control approach."

Famous for the limestone-tinted crystal blue water of its springs, Ozark National Scenic Riverways, a 134-mile-long park that came under federal protection in the 1960s, includes the Current and Jacks Fork rivers in southern Missouri, popular destinations for campers, anglers and float trippers.

The organization said the area was included on the list for the first time due to overuse and concern over management.

"It's almost being loved to death," said Fay Augustyn, conservation assistant with the group. "People have been enjoying the river so much there have been erosion and pollution. We're just concerned about the area's clean water and that the experience around the rivers will be lost."

Augustyn said that the annual list, which has been issued by the group since 1986, changes frequently and is designed to raise awareness of pressing issues or decisions at a given point in time so people can take action.

The group's website said criteria for nomination include waterways that have a major decision that the public can influence in the coming year and the significance of the river to people and animals as well as the magnitude of the threat.

None of last year's listed rivers was the same as this year's.

A release by the organization cited unmanaged dirt roads, excessive vehicular access points and extensive unofficial horse trails as threats to Ozark National Scenic Riverways.

The National Park Service is at present working on a draft of a new general management plan, due to be released for public comment early next year. American Rivers encouraged officials to use the document as an opportunity to examine the issues it has raised more closely.

Kathleen Logan Smith, executive director of the Missouri Coalition for the Environment, said she supported the group's move.

"I think it will help bring attention to one of our national treasures, which is the whole point of having it listed," Smith said.

She said dozens of extra places of contact for vehicles and transport animals have sprung up over the years creating a danger of pollution and equine waste in the water.

"We'd like to see fewer access points and horses managed in a way that protects the resource," Smith said. "Nobody I know would say 'Get the horses out of the park.' It's a wonderful way to enjoy one of our national parks. There just needs to be more enforcement of standards."

Present National Park Service rules prohibit use of ATVs on trails, in rivers or off-road, and horse riders are encouraged not to ride in the water any longer than absolutely necessary.

Faye Walmsley, chief of interpretation and public information officer for the National Park Service office in the park, said that Ozark National has been in the process of developing a new general management plan for several years. The park's previous blueprint dates to 1984.

"It's going to be identifying what the park needs to do 20-25 years out," she said.

Walmsley, who said she had not been in contact with American Rivers, said she questioned some of the numbers in the group's report and was presently comparing them with findings from a user-capacity study done by the park last summer.

Walmsley called Ozark National "beautiful" and said the park service works hard to monitor water quality and is required to comply with the provisions of the Clean Water Act. She noted that the purpose of the management plan was precisely to assess any issues or challenges that might be occurring and welcomed public involvement in the formation of the new plan.

"We encourage people to participate in the general management process," she said. "If folks have concerns about some of the issues and challenges that we're facing, we want them to participate in the open houses that we'll have, find out more online and make comments."

Walmsley hopes the final plan will be issued by October 2012.

Adam Wiseman, a St. Louisan who went camping along the Current River just days ago, won't be in town that long. He said he will soon be moving to New York and wanted to experience the Missouri wilderness of the park once more before leaving. He said he thought it was good that the American Rivers report might call attention to any potential problems associated with heavy use of the park by humans.

"Even on a cold weekend like last weekend, there are people floating on the river," Wiseman said.