Where In The Pacific Northwest Are David, Theo & Ruby?

Incoming four emails last night, asking the question, "Where in the PNW are David, Theo & Ruby?"

Each email had one photo, with text saying Hint #1, Hint #2, Hint #3, with the final email text saying "Not sure if this a place you’ve ever explored. It would have looked much different when you were a kid and even, I think, most of the time you lived here."

When I saw the first photo hint, that being the one above, before I read the text in the 4th email, which said "not sure if this is a place you've ever explored," I thought it was likely Birch Bay. 

Then the next hint...

Definitely not Birch Bay.

On to hint #3...

The Padilla Bay tide lands south of Bay View State Park, maybe? But this does not quite look like the Padilla Bay tide lands.

On to the final hint...

Well, I believe I have driven by this location a number of times, driving Interstate 5 between Tacoma and Olympia.

That would make where David, Theo & Ruby are in the Pacific Northwest to be the Nisqually National Wildlife Refuge.

I do not remember this area as developed, like it is now. I do not remember if this was a National Wildlife Refuge when I lived in Washington. I just remember this location, where the Nisqually River empties into Puget Sound as the Nisqually Mudflats.

I wonder where in the Pacific Northwest David, Theo & Ruby are going next?