Well, the problem is jurisdiction and ownership. Big Sur isn't a National Park, it's really just a region, including a State Park scattered around an area with privately owned land as well. In contrast, Muir Woods is just a very small national monument (AFAIK, hence its small visitation) and Yosemite has the protection of the NPS and federal government.

Looks like the hotel was on private land, so really the issue is the waterway modifications and general carelessness with regards to laws and regulations. Those laws and regulations are still extremely important: water is a complex subject especially in the west. In this case the river flows directly through the state park and has many ecological considerations, as well as fishing (salmon spawning) and other wildlife.

So, it's still private land, but anything that happens to a stream in California has gotta be done right or you're in trouble, and there's a damn good reason why even if you don't like fish.