Index: src/saveload/company_sl.cpp
===================================================================
--- src/saveload/company_sl.cpp	(revision 27153)
+++ src/saveload/company_sl.cpp	(working copy)
@@ -180,6 +180,9 @@
 						if (IsLock(tile) && GetLockPart(tile) == LOCK_PART_MIDDLE) {
 							/* The middle tile specifies the owner of the lock. */
 							c->infrastructure.water += 3 * LOCK_DEPOT_TILE_FACTOR; // the middle tile specifies the owner of the
+							if (GetWaterClass(tile) != WATER_CLASS_CANAL) {
+								c->infrastructure.water++;
+							}
 							break; // do not count the middle tile as canal
 						}
 					}
Index: src/water_cmd.cpp
===================================================================
--- src/water_cmd.cpp	(revision 27153)
+++ src/water_cmd.cpp	(working copy)
@@ -258,10 +258,14 @@
 
 	/* middle tile */
 	WaterClass wc_middle = IsWaterTile(tile) ? GetWaterClass(tile) : WATER_CLASS_CANAL;
-	ret = DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
-	if (ret.Failed()) return ret;
-	cost.AddCost(ret);
 
+	if (!IsWaterTile(tile)) {
+		ret = DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
+		if (ret.Failed()) return ret;
+		cost.AddCost(ret);
+		cost.AddCost(_price[PR_BUILD_CANAL]);
+	}
+
 	/* lower tile */
 	WaterClass wc_lower = IsWaterTile(tile - delta) ? GetWaterClass(tile - delta) : WATER_CLASS_CANAL;
 
@@ -298,6 +302,7 @@
 		if (c != NULL) {
 			/* Counts for the water. */
 			if (!IsWaterTile(tile - delta)) c->infrastructure.water++;
+			if (!IsWaterTile(tile)) c->infrastructure.water++;
 			if (!IsWaterTile(tile + delta)) c->infrastructure.water++;
 			/* Count for the lock itself. */
 			c->infrastructure.water += 3 * LOCK_DEPOT_TILE_FACTOR; // Lock is three tiles.
@@ -348,6 +353,9 @@
 		if (GetWaterClass(tile) == WATER_CLASS_RIVER) {
 			MakeRiver(tile, Random());
 		} else {
+			if (c != NULL) {
+				c->infrastructure.water--;
+			}
 			DoClearSquare(tile);
 		}
 		MakeWaterKeepingClass(tile + delta, GetTileOwner(tile + delta));
@@ -1276,8 +1284,14 @@
 
 	/* No need to dirty company windows here, we'll redraw the whole screen anyway. */
 	if (is_lock_middle) Company::Get(old_owner)->infrastructure.water -= 3 * LOCK_DEPOT_TILE_FACTOR; // Lock has three parts.
+	if (GetWaterClass(tile) == WATER_CLASS_CANAL && is_lock_middle) {
+		Company::Get(old_owner)->infrastructure.water--;
+	}
 	if (new_owner != INVALID_OWNER) {
 		if (is_lock_middle) Company::Get(new_owner)->infrastructure.water += 3 * LOCK_DEPOT_TILE_FACTOR; // Lock has three parts.
+		if (GetWaterClass(tile) == WATER_CLASS_CANAL && is_lock_middle) {
+			Company::Get(new_owner)->infrastructure.water++;
+		}
 		/* Only subtract from the old owner here if the new owner is valid,
 		 * otherwise we clear ship depots and canal water below. */
 		if (GetWaterClass(tile) == WATER_CLASS_CANAL && !is_lock_middle) {