Study examines impact of climate change on popular Missouri River

JEFFERSON CITY — Visitors to the Eleven Point River, as well as the giant Ozark hellbenders salamanders that live there, could be affected by rising temperatures and extreme flooding attributed to climate change.

In May, the U.S. Forest Service released a new, comprehensive management plan for the federally protected Eleven Point Wild and Scenic River. It includes a section on the challenges posed by climate change, including potential shifts in visitor patterns, heavy rainfall and flooding, and potential habitat loss.

According to state and federal officials, giant salamanders in the Ozarks are particularly threatened by major flooding, which can shift the rocks and boulders under which the salamanders live, wiping out their habitat.

That’s bad news for Missouri and wildlife enthusiasts. Lawmakers officially designated the Ozark hellbender a state endangered species in 2019. The Missouri Department of Conservation, the St. Louis Zoo and other partners have been working for more than two decades on a captive breeding program to restore the population.

According to the Forest Service’s plan, changes in water quality could stress certain species and the growth of invasive terrestrial and aquatic species “may outpace organizational capacity to manage them, in part because of limited access to streambanks.”

In a statement to the Post-Dispatch, the Forest Service said the endangered Ozark hellbender and non-native trout present in the park “could potentially be negatively impacted by higher temperatures.”

For humans, the plan says, warm weather and changing hydrology “will impact where people can camp and the ease with which they can move through the water.”

It adds that “visitor numbers may increase in the spring and fall due to changes in weather” and that higher temperatures and heat warning days “may increase visitors’ exposure to unsafe conditions.”

The Forest Service’s management plan for Eleven Point is the first update since 1975. In 1968, Congress protected 44 miles of the river in Oregon County.

Cody Norris, spokesman for the Mark Twain National Forest, said the management plan’s statement about heat warning days does not necessarily mean fewer people will visit the river during extreme heat.

He said people should be aware of the danger and take precautions such as drinking plenty of fluids and reducing sun exposure.

“Maybe more people would visit a river on extremely hot days in summer because they have the time and inclination to get out, but they think it is not safe to walk in the heat,” Norris said.

Missouri state herpetologist Jeff Briggler said that when it comes to hellbenders dealing with extreme heat, spring-fed streams create a “buffer” effect.

“I don’t think a few degrees is going to push the hellbenders over the edge,” Briggler said. “I think the water is very buffered by those spring influences. And I think the potential impact is going to be minimal. If the springs start to rise in temperature now, that’s a different story.”

Briggler said a major threat to the Hellbenders is heavy rainfall, “which seems to be happening at a faster pace now.”

The impact can be especially pronounced during “massive” rainstorms, such as 2 to 3 inches of rain in a very short time in an area without riverbank protection – a system of trees and other vegetation along the riverbank that filters the water and slows its flow.

Briggler pointed to flooding in southern Missouri in 2017.

“The North Fork drainage and the Bryant Creek drainage in particular had catastrophic flooding,” he said.

Briggler said the flooding damaged “the river bottom, and it moved rocks the size of cars and the habitat that these animals need. And we saw a dramatic decline in the halberd populations.”

Trisha Crabill, endangered species coordinator for the U.S. Fish and Wildlife Service, said extreme flooding can move large rocks downstream. “If there’s a basking shark underneath, say a 6-foot rock, and it’s moved downstream, that’s going to cause injury, mortality and disrupt reproductive behavior.

“The flooding is likely to have an impact on the species — at least that’s what we expect,” she said. “One thing we know — you can’t go wrong — is trying to increase shoreline protection.”