The 6-foot leash rule shows up at almost every park, and it isn't bureaucratic fussiness. It's what keeps your dog, the wildlife, and other hikers out of trouble.
Most parks cap leashes at 6 feet and ban retractable leashes outright. A retractable lets a dog range 15 or 20 feet ahead, enough to reach a snake, a cliff edge, or another hiker before you can react. Six feet keeps your dog inside your control and your reach.
Loose or long-leashed dogs chase wildlife, and it goes badly in both directions. A dog can flush nesting birds, stress animals conserving winter energy, or corner a porcupine. In predator country, a loose dog can bring a coyote or bear back toward you.
Dog waste carries bacteria that don't belong in the ecosystem, and it's one of the top reasons trails and beaches close to dogs. Bag it and carry it out, every time.