I have noticed two spawn points in my hometown only Spohn Pokémon that are water type. Since the game has launched I have never seen any Pokémon Spohn there that were not water type. They normally have different Pokémon every time I go there but always watert they normally have different Pokémon every time I go there but always water typoeokemon. Has anyone else seen this?
I have noticed sometimes quite similiar to your situation. There is this one spawn point at my school that will spawn that exact same pokemon but it seems to change everytime there is a new best migration. Right now there is only dunsparce spawning at the spawn point. Before it was psyduck.
The spawn points I am referencing have a different water type Pokémon every time I visit them It might be magikarp then time and a squirtle an hour later. As far as I have been able to tell these both have stayed water type since the game launched.
These are different than typical frequent spawn where a certain Pokémon spawns there every time or every day at certain times.
There is are a couple areas on Virginia Tech’s campus that are 24/7 water biomes since the game came out even the official nests will rotate water Pokémon