I'm tempted to name this one after Ricardo Bayon, because it came up in our conversation a few years back, but I'll spare him. We were talking about the problem I'd seen in Chicago and Minnesota where municipalities were enacting rules that prevented wetland credits from leaving their territory -- Elgin didn't want to lose its wetlands to rural Kane County, etc. -- even though both of them were in the same Corps service area. This was really getting in the way of local wetland bankers.
Ricardo waved off the possibility of this happening in California. But I suggested something like this: "Any environmental amenity sufficiently valuable to sustain a viable ecosystem service credit market is valuable enough to stimulate policies restricting its flight from any territory concerned about attracting an affluent residential tax base."
Sounded smart. No idea at all if this has happened!