Fresh off a ninety-minute hike that led me down a rocky hillside, past the crumbling remains of an old stone chimney, and onto a sandy beach along Lake Travis, just east of Marble Falls, I ease myself into a steamy outdoor tub and tip back my head. Dang, I think. Parks have gotten fancy.As I recall, Texans once visited parks simply to do typical outdoorsy stuff: hike, pitch a tent, jump in a river, and maybe grill up a few burgers. But at a string of Lower Colorado River Authority (LCRA) parks, including Shaffer Bend Recreation Area, where I lolled like a dumpling in a soup pot, that’s just the starting point.The LCRA produces and delivers electric power and manages roughly six hundred miles of…