To be fair, the purpose of state parks is not for military training. The Navy has Indian Island and numerous bases around the Puget Sound. I don’t know if the Navy notifies the public about park operations, but it should
That said, the NIMBYs are strong around Whidbey Island, protesting the sound of training naval jets out of the NAS. The jets can’t be reasonably expected to train above bases only.
A couple of circuits of the training facility, you’re familiarized. You learn more by training in unfamiliar territory.