--- a/src/water_cmd.cpp	Wed Jan 16 00:33:28 2008 +0000
+++ b/src/water_cmd.cpp	Wed Jan 16 01:18:15 2008 +0000
@@ -648,6 +648,9 @@
 				MarkTileDirtyIfCanal(target + TileOffsByDir(dir));
 			}
 		}
+
+		/* update signals if needed */
+		UpdateSignalsInBuffer();
 	}
 }