Slightly downstream from where the San Marcos and Blanco rivers meet in Central Texas, Tom Goynes likes to show visitors to his campground the “symphony of birds,” as he calls it, in the mornings — the woodpeckers, the cardinals. He routinely sees deer, bobcats and coyotes.

“You’re surrounded by God and everything that he’s created,” said Mr. Goynes, 74, who has operated campgrounds on the San Marcos River since 1972. “It’s a whole lot better than being in any cathedral.”

In the region of Texas known as the Hill Country, the rivers that etch an otherwise semiarid terrain are a defining feature: They have long offered a cool respite from unforgiving heat, access to wildlife and a splendor that can resonate in a way that feels spiritual.

When some of those rivers quickly rose early on July 4, unleashing floodwaters that killed more than 100 people, with dozens of others still missing, the disaster served as an abrupt reminder of the danger that has always lurked in a place referred to as Flash Flood Alley.

But the substantial loss of life also reflected these waterways’ magnetic allure. The floodwaters crashed through beloved sleep-away camps, vacation properties and homes built along the banks. Some of those houses belonged to families who had staked their claims generations ago, and plenty of others to newcomers who had sought out this part of Texas with visions of a life that felt more rustic.