The Corps is greatly overworked these days and unless your project results in off site problems with neighbors it is very unlikely they would even know about. Second the Corps lost a huge lawsuit in the midwest several years ago that says they can't regulate "isolated wetlands". So if your pond is not built by damaging up a stream they couldn't regulate if they wanted to. There is another court case, (Deloche Doctrine), they have lost that says they can't regulate excavtion in a wetland. Fill in a wetland without a permit and you go to jail, excavate a wetland without placing a fill there and you're ok. I wouldn't get a permit from them if your project was mine.
