Looking for Open Water Swimming in Del. Cty, PA

I am currently working as a consultant on a project between
Philadelphia and Wilmington, DE. I'm trying to stick to my training
routine and am looking for somewhere to do some outdoor lake swimming
around Wilminton, DE or West Chester/Chadds Ford, PA. If anyone has
advice on where to find places to swim outdoor in this area, please
post it on here or email me directly - really appreciate it. Thanks!!