Sure. No one has stopped us from going in the creeks so far. If you go far enough down the main trail... almost to the area where the trail opens to the railroad and the Susquehanna, there are some really nice pools in the creek. Creek shoes or "get wet" shoes are recommended with rocks, etc. in the beds. My guess is everything you do is at your own risk. Check and make sure to comply with the preserve rules posted in the main parking area. Have fun. Be safe.
Swimming is not explicitly prohibited by Lancaster County Conservancy's rules and I often see people taking a dip about 2/3 of the way down the tail near the footbridge. I'd say it's a safe bet. Keep in mind though, that's it not the most private place to swim in the area and that most of the creek is too shallow for swimming.
No swinning. Wadding. Very shallow rocks everywhere. Be safe. Play safe.
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