The canoe slides easily through the shallow water just below Alley Spring until suddenly it shakes to a stop.
The bottom of the boat scrapes along the gravel sitting mere inches below the surface. You have to dig your paddle into the rocks or get out and push the boat to deeper water if you want to move forward.
Shallow spots like this pop up frequently along the Jacks Fork River, and if you run a business helping vacationers taking float trips, this might make you worry. Debris from the riverbank can make gravel bars and already shallow spots grow wider, which changes the way boaters must navigate the water.
Float down the river, and you can see why.
On one side, a chunk of the bank has collapsed, taking four sycamore trees into the river with it. Plants, dirt and rocks crumble into the water from this cut bank.
This erosion poses a dilemma for conservationists, said Rebecca Landewe, Current River project manager at the Nature Conservancy. When people alter an environment with their activities, park rangers can often work with visitors to slow the effects or stop the problem.
Unlike beer cans at the bottom of the river, erosion can happen without anyone’s help. This spring, for example, heavy rain pounded debris into the river.
“We have a regulatory fallback (with some problems) — with sediment, there’s not,” Landewe said.
The Nature Conservancy doesn’t carefully monitor the level of sediment in the river, and even if it did, Landewe said, determining its importance is hard.
“There’s no standard measure to say ‘This is a problem,’ ” she said.