As the Yellowstone River neared its record-setting peak on June 13, I stood on a wall of rocks that protects the town of Livingston, Montana, then trudged along it, marveling at the force of the flood. The river had begun to crest the rocks in places, slurping muddy water onto the pavement.
It’s easy to feel as if the stones in that wall are a natural part of the landscape. The Yellowstone is known as the longest free-flowing river in the Lower 48, because there are no dams that restrict its flow. But those rocks, known as riprap, are not a natural formation; they were intentionally put in place to confine the river and protect the property along its banks. Riprap like this lines more than 100 miles of the Yellowstone River.
The June flood, which destroyed roads and homes across a huge swath of south-central Montana, created new channels on formerly dry land. The water gnawed at riverbanks that had been stable for decades. The wall where I stood remained more or less intact, but nearby, the sheer force of the current pried loose thousand-pound riprap stones and heaved them downstream.
Now, as rebuilding begins, a decades-old problem is once again arising: How can people protect their property while preserving the health of the already imperiled river?