I looked there yesterday and it seems that it is open to use. There are some "private' spaces closest to the powerhouse, but the rest looks like public use to me. The only prob is acces to the water, its all rock, all down-hill.
Hey Spur, if you're looking at the lake, off to the right (After you come under the bridge) there are some steps coming down to the lake. It's still all rocks on either side though.