As part of a civilian search and rescue team, Marks is helping guide ground crews to areas still untouched nearly a week after deadly floodwaters swept through Central Texas.

“It’s hard not to feel like you are surrounded by a higher power when you’re down there, because it’s just so beautiful,” my friend Olivia Marrus told me.

Since its construction in 1926, the camp — which promised cabins “snugly arranged” in a “picturesque bend” in the river — repeatedly experienced flood disruptions, including evacuations or damage to s...