diff -ru openttd-1.2.3/bin/ai/regression/regression.nut openttd-1.2.3mod/bin/ai/regression/regression.nut
--- openttd-1.2.3/bin/ai/regression/regression.nut	2012-10-31 22:39:02.000000000 +0100
+++ openttd-1.2.3mod/bin/ai/regression/regression.nut	2012-12-04 21:56:43.000000000 +0100
@@ -552,6 +552,7 @@
 	print("  BT_CLEAR_ROCKY:  " + AITile.GetBuildCost(AITile.BT_CLEAR_ROCKY));
 	print("  BT_CLEAR_FIELDS: " + AITile.GetBuildCost(AITile.BT_CLEAR_FIELDS));
 	print("  BT_CLEAR_HOUSE:  " + AITile.GetBuildCost(AITile.BT_CLEAR_HOUSE));
+	print("  BT_CLEAR_RIVER:  " + AITile.GetBuildCost(AITile.BT_CLEAR_RIVER));
 }
 
 function cost_callback(old_path, new_tile, new_direction, self) { if (old_path == null) return 0; return old_path.GetCost() + 1; }
diff -ru openttd-1.2.3/src/script/api/ai/ai_tile.hpp.sq openttd-1.2.3mod/src/script/api/ai/ai_tile.hpp.sq
--- openttd-1.2.3/src/script/api/ai/ai_tile.hpp.sq	2012-10-31 22:38:56.000000000 +0100
+++ openttd-1.2.3mod/src/script/api/ai/ai_tile.hpp.sq	2012-12-04 21:49:01.000000000 +0100
@@ -66,6 +66,7 @@
 	SQAITile.DefSQConst(engine, ScriptTile::BT_CLEAR_ROCKY,              "BT_CLEAR_ROCKY");
 	SQAITile.DefSQConst(engine, ScriptTile::BT_CLEAR_FIELDS,             "BT_CLEAR_FIELDS");
 	SQAITile.DefSQConst(engine, ScriptTile::BT_CLEAR_HOUSE,              "BT_CLEAR_HOUSE");
+	SQAITile.DefSQConst(engine, ScriptTile::BT_CLEAR_RIVER,              "BT_CLEAR_RIVER");
 
 	ScriptError::RegisterErrorMap(STR_ERROR_ALREADY_AT_SEA_LEVEL,    ScriptTile::ERR_TILE_TOO_HIGH);
 	ScriptError::RegisterErrorMap(STR_ERROR_ALREADY_AT_SEA_LEVEL,    ScriptTile::ERR_TILE_TOO_LOW);
@@ -80,6 +81,7 @@
 	SQAITile.DefSQStaticMethod(engine, &ScriptTile::IsBuildable,                "IsBuildable",                2, ".i");
 	SQAITile.DefSQStaticMethod(engine, &ScriptTile::IsBuildableRectangle,       "IsBuildableRectangle",       4, ".iii");
 	SQAITile.DefSQStaticMethod(engine, &ScriptTile::IsWaterTile,                "IsWaterTile",                2, ".i");
+	SQAITile.DefSQStaticMethod(engine, &ScriptTile::IsRiverTile,                "IsRiverTile",                2, ".i");
 	SQAITile.DefSQStaticMethod(engine, &ScriptTile::IsCoastTile,                "IsCoastTile",                2, ".i");
 	SQAITile.DefSQStaticMethod(engine, &ScriptTile::IsStationTile,              "IsStationTile",              2, ".i");
 	SQAITile.DefSQStaticMethod(engine, &ScriptTile::IsSteepSlope,               "IsSteepSlope",               2, ".i");
diff -ru openttd-1.2.3/src/script/api/game/game_tile.hpp.sq openttd-1.2.3mod/src/script/api/game/game_tile.hpp.sq
--- openttd-1.2.3/src/script/api/game/game_tile.hpp.sq	2012-10-31 22:38:55.000000000 +0100
+++ openttd-1.2.3mod/src/script/api/game/game_tile.hpp.sq	2012-12-04 21:49:56.000000000 +0100
@@ -66,6 +66,7 @@
 	SQGSTile.DefSQConst(engine, ScriptTile::BT_CLEAR_ROCKY,              "BT_CLEAR_ROCKY");
 	SQGSTile.DefSQConst(engine, ScriptTile::BT_CLEAR_FIELDS,             "BT_CLEAR_FIELDS");
 	SQGSTile.DefSQConst(engine, ScriptTile::BT_CLEAR_HOUSE,              "BT_CLEAR_HOUSE");
+	SQGSTile.DefSQConst(engine, ScriptTile::BT_CLEAR_RIVER,              "BT_CLEAR_RIVER");
 
 	ScriptError::RegisterErrorMap(STR_ERROR_ALREADY_AT_SEA_LEVEL,    ScriptTile::ERR_TILE_TOO_HIGH);
 	ScriptError::RegisterErrorMap(STR_ERROR_ALREADY_AT_SEA_LEVEL,    ScriptTile::ERR_TILE_TOO_LOW);
@@ -80,6 +81,7 @@
 	SQGSTile.DefSQStaticMethod(engine, &ScriptTile::IsBuildable,                "IsBuildable",                2, ".i");
 	SQGSTile.DefSQStaticMethod(engine, &ScriptTile::IsBuildableRectangle,       "IsBuildableRectangle",       4, ".iii");
 	SQGSTile.DefSQStaticMethod(engine, &ScriptTile::IsWaterTile,                "IsWaterTile",                2, ".i");
+	SQGSTile.DefSQStaticMethod(engine, &ScriptTile::IsRiverTile,                "IsRiverTile",                2, ".i");
 	SQGSTile.DefSQStaticMethod(engine, &ScriptTile::IsCoastTile,                "IsCoastTile",                2, ".i");
 	SQGSTile.DefSQStaticMethod(engine, &ScriptTile::IsStationTile,              "IsStationTile",              2, ".i");
 	SQGSTile.DefSQStaticMethod(engine, &ScriptTile::IsSteepSlope,               "IsSteepSlope",               2, ".i");
diff -ru openttd-1.2.3/src/script/api/script_tile.cpp openttd-1.2.3mod/src/script/api/script_tile.cpp
--- openttd-1.2.3/src/script/api/script_tile.cpp	2012-10-31 22:38:58.000000000 +0100
+++ openttd-1.2.3mod/src/script/api/script_tile.cpp	2012-12-04 21:39:30.000000000 +0100
@@ -64,6 +64,13 @@
 	return ::IsTileType(tile, MP_WATER) && !::IsCoast(tile);
 }
 
+/* static */ bool ScriptTile::IsRiverTile(TileIndex tile)
+{
+	if (!::IsValidTile(tile)) return false;
+
+	return ::IsTileType(tile, MP_WATER) && ::IsRiver(tile);
+}
+
 /* static */ bool ScriptTile::IsCoastTile(TileIndex tile)
 {
 	if (!::IsValidTile(tile)) return false;
@@ -302,6 +309,7 @@
 		case BT_CLEAR_ROCKY:  return ::GetPrice(PR_CLEAR_ROCKS, 1, NULL);
 		case BT_CLEAR_FIELDS: return ::GetPrice(PR_CLEAR_FIELDS, 1, NULL);
 		case BT_CLEAR_HOUSE:  return ::GetPrice(PR_CLEAR_HOUSE, 1, NULL);
+		case BT_CLEAR_RIVER:  return ::GetPrice(PR_CLEAR_WATER, 1, NULL);
 		default: return -1;
 	}
 }
diff -ru openttd-1.2.3/src/script/api/script_tile.hpp openttd-1.2.3mod/src/script/api/script_tile.hpp
--- openttd-1.2.3/src/script/api/script_tile.hpp	2012-10-31 22:38:58.000000000 +0100
+++ openttd-1.2.3mod/src/script/api/script_tile.hpp	2012-12-04 21:40:23.000000000 +0100
@@ -118,6 +118,7 @@
 		BT_CLEAR_ROCKY,  ///< Clear a tile with rocks
 		BT_CLEAR_FIELDS, ///< Clear a tile with farm fields
 		BT_CLEAR_HOUSE,  ///< Clear a tile with a house
+		BT_CLEAR_RIVER,	 ///< Clear a tile with a river
 	};
 
 	/**
@@ -153,6 +154,14 @@
 	static bool IsWaterTile(TileIndex tile);
 
 	/**
+	 * Checks whether the given tile is actually a river tile.
+	 * @param tile The tile to check on.
+	 * @pre ScriptMap::IsValidTile(tile).
+	 * @return True if and only if the tile is a river tile.
+	 */
+	static bool IsRiverTile(TileIndex tile);
+
+	/**
 	 * Checks whether the given tile is actually a coast tile.
 	 * @param tile The tile to check.
 	 * @pre ScriptMap::IsValidTile(tile).