diff --git a/data.yml b/data.yml
index e813cc0..33cb003 100644
--- a/data.yml
+++ b/data.yml
@@ -48,8 +48,11 @@ Layer:
               SELECT * FROM water_z6
               WHERE z(!scale_denominator!) = 6
               UNION ALL
-              SELECT * FROM water_z8
-              WHERE z(!scale_denominator!) BETWEEN 8 AND 10
+              SELECT ST_SimplifyPreserveTopology(geom, 200) AS geom FROM water_z8
+              WHERE z(!scale_denominator!) = 8
+              UNION ALL
+              SELECT ST_SimplifyPreserveTopology(geom, 100) AS geom FROM water_z8
+              WHERE z(!scale_denominator!) BETWEEN 9 AND 10
               UNION ALL
               SELECT * FROM water_z11
               WHERE z(!scale_denominator!) = 11
diff --git a/schema/layers/water.sql b/schema/layers/water.sql
index 21c2120..663450d 100644
--- a/schema/layers/water.sql
+++ b/schema/layers/water.sql
@@ -54,10 +54,18 @@ CREATE OR REPLACE VIEW water_z6 AS (
 
 CREATE OR REPLACE VIEW water_z8 AS (
     SELECT way AS geom FROM water_areas
-    WHERE way_area > 100000
+    WHERE way_area > 1000000
 	UNION ALL
 	SELECT way AS geom FROM waterways
-	WHERE waterway IN ('river')
+	WHERE waterway IN ('river') AND ST_Length(way) > 10000
+);
+
+CREATE OR REPLACE VIEW water_z9 AS (
+    SELECT way AS geom FROM water_areas
+    WHERE way_area > 500000
+	UNION ALL
+	SELECT way AS geom FROM waterways
+	WHERE waterway IN ('river') AND ST_Length(way) > 5000
 );
 
 CREATE OR REPLACE VIEW water_z11 AS (