The place you are referring to is called the Power Dam. It is directly below Potato Salad Hill on Mill Creek. While the water is about 12-15 feet near the dam it is and always has been the place where many locals choose to hang out and swim. It is likely to be somewhat crowded, depending on what you define as crowded.
Lefthand was mentioned earlier, it is another 1 1/2 to 2 miles upstream. Obviously on the lefthand fork of the creek. It is considerably colder water and may not be deep enough this late in the year or if no one rebuilt the dam that causes the water to back up into a pool.
The Power Dam can be driven to, from either side. Lefthand must be hiked to from the Power Dam.