Steve: see Derek Whaley’s photo and response below re: your request about the swimming hole you recall from the 1950’s. Does this look/sound familiar?
It could be the swimming hole near Siesta in Brookdale. There are still remnants of a swimming hole there with stone walls and the remains of a plank-built dam. You can kind of see it in this photograph. There are actually two swimming holes in this photo, the large one at the bottom and a smaller one at the top. The top one is the one with the stone walls. It’s right under the Irwin Way bridge.