The screenshot clearly shows the river border's water source is significantly higher than sea level—I'd estimate about 50m above its intended height. For context, all water sources on the map, including sea level were initially set at a uniform elevation of 250m from bottom of map.
Regarding water pumping station in original map there is not even shore on this side of bridge to even place it there, but the raised river source 50m above sea level will flood pretty match whole map eventually as 90% of buildable area is only 30m above sea level.
There are two likely reasons for this discrepancy:
- Map Modification: It's possible the map was edited, which could have inadvertently altered this specific water source's elevation.
- Potential Game Bug: My suspicion is that this is a game bug, especially given how close this water source is to the map's edge. When you start a new game, objects seem to be actively 'placed' and conformed onto the heightmap (you can see this with roads often looking different than in the editor). There's a known issue where sampling the world map's height or smoothing terrain at the border of the playable and world map doesn't work correctly. If this problematic water source is attempting to sample a height outside in the world map, it could result in it being placed at a much higher elevation.
Possible Solutions
Here are a few ways to address this:
- Adjust in Save Game: If you want to keep your current city, you can manually move the border river water source to the 250m (0m) the sea level height. You'll need to use the Water Features mod within your save game while paused.
- Redownload Map: Try deleting the map file (in folder numbered 76483_4) from C:UsersYOURUSERNAMEAppDataLocalLowColossal OrderCities Skylines II.cacheModsmods_subscribed. Then, let the game redownload it and start a new city.
- Map Adjustment (Requires New City): I could potentially move the border river slightly further away from the map edge. This might fix the issue, but it would require you to start a new city. Let me know if that's something you'd prefer!
Btw I can't repeat the issue described on my pc.