Index: src/tree_cmd.cpp
===================================================================
--- src/tree_cmd.cpp	(revision 11015)
+++ src/tree_cmd.cpp	(working copy)
@@ -255,6 +255,11 @@
 					cost.AddCost(_price.build_trees * 2);
 					break;
 
+				case MP_WATER:
+					msg = STR_3807_CAN_T_BUILD_ON_WATER;
+					continue;
+					break;
+
 				case MP_CLEAR:
 					if (!IsTileOwner(tile, OWNER_NONE) ||
 							IsBridgeAbove(tile)) {
Index: src/clear_cmd.cpp
===================================================================
--- src/clear_cmd.cpp	(revision 11015)
+++ src/clear_cmd.cpp	(working copy)
@@ -403,8 +403,6 @@
 
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
 
-	if (!EnsureNoVehicle(tile)) return CMD_ERROR;
-
 	if (IsOwnedLandTile(tile) && IsTileOwner(tile, _current_player)) {
 		return_cmd_error(STR_5807_YOU_ALREADY_OWN_IT);
 	}
Index: src/water_cmd.cpp
===================================================================
--- src/water_cmd.cpp	(revision 11015)
+++ src/water_cmd.cpp	(working copy)
@@ -66,12 +66,9 @@
 
 	SET_EXPENSES_TYPE(EXPENSES_CONSTRUCTION);
 
-	if (!EnsureNoVehicle(tile)) return CMD_ERROR;
-
 	Axis axis = Extract<Axis, 0>(p1);
 
 	tile2 = tile + (axis == AXIS_X ? TileDiffXY(1, 0) : TileDiffXY(0, 1));
-	if (!EnsureNoVehicle(tile2)) return CMD_ERROR;
 
 	if (!IsClearWaterTile(tile) || !IsClearWaterTile(tile2))
 		return_cmd_error(STR_3801_MUST_BE_BUILT_ON_WATER);
@@ -288,15 +285,15 @@
 		case WATER_TILE_CLEAR:
 			if (flags & DC_NO_WATER) return_cmd_error(STR_3807_CAN_T_BUILD_ON_WATER);
 
-			/* Make sure no vehicle is on the tile */
-			if (!EnsureNoVehicle(tile)) return CMD_ERROR;
-
 			/* Make sure it's not an edge tile. */
 			if (!IS_INT_INSIDE(TileX(tile), 1, MapMaxX() - 1) ||
 					!IS_INT_INSIDE(TileY(tile), 1, MapMaxY() - 1)) {
 				return_cmd_error(STR_0002_TOO_CLOSE_TO_EDGE_OF_MAP);
 			}
 
+			/* Make sure no vehicle is on the tile */
+			if (!EnsureNoVehicle(tile)) return CMD_ERROR;
+
 			if (GetTileOwner(tile) != OWNER_WATER && GetTileOwner(tile) != OWNER_NONE && !CheckTileOwnership(tile)) return CMD_ERROR;
 
 			if (flags & DC_EXEC) DoClearSquare(tile);
@@ -308,12 +305,6 @@
 			/* Make sure no vehicle is on the tile */
 			if (!EnsureNoVehicle(tile)) return CMD_ERROR;
 
-			/* Make sure it's not an edge tile. */
-			if (!IS_INT_INSIDE(TileX(tile), 1, MapMaxX() - 1) ||
-					!IS_INT_INSIDE(TileY(tile), 1, MapMaxY() - 1)) {
-				return_cmd_error(STR_0002_TOO_CLOSE_TO_EDGE_OF_MAP);
-			}
-
 			if (flags & DC_EXEC) DoClearSquare(tile);
 			if (slope == SLOPE_N || slope == SLOPE_E || slope == SLOPE_S || slope == SLOPE_W) {
 				return CommandCost(_price.clear_water);