diff --git a/src/saveload/afterload.cpp b/src/saveload/afterload.cpp
--- a/src/saveload/afterload.cpp
+++ b/src/saveload/afterload.cpp
@@ -3111,6 +3111,13 @@ bool AfterLoadGame()
 		FOR_ALL_INDUSTRIES(ind) if (ind->neutral_station != NULL) ind->neutral_station->industry = ind;
 	}
 
+	{
+		/* Update water class for trees for all current savegame versions. */
+		for (TileIndex t = 0; t < map_size; t++) {
+			if (IsTileType(t, MP_TREES)) SetWaterClass(t, GetTreeGround(t) == TREE_GROUND_SHORE ? WATER_CLASS_SEA : WATER_CLASS_INVALID);
+		}
+	}
+
 	/* Compute station catchment areas. This is needed here in case UpdateStationAcceptance is called below. */
 	Station::RecomputeCatchmentForAll();