diff --git a/src/objectliterals.exports b/src/objectliterals.exports
index 1abc752745..d4146838ae 100644
--- a/src/objectliterals.exports
+++ b/src/objectliterals.exports
@@ -133,6 +133,7 @@
 @exportObjectLiteralProperty ol.source.TiledWMSOptions.crossOrigin null|string|undefined
 @exportObjectLiteralProperty ol.source.TiledWMSOptions.extent ol.Extent|undefined
 @exportObjectLiteralProperty ol.source.TiledWMSOptions.tileGrid ol.tilegrid.TileGrid|undefined
+@exportObjectLiteralProperty ol.source.TiledWMSOptions.transparent boolean|undefined
 @exportObjectLiteralProperty ol.source.TiledWMSOptions.maxZoom number|undefined
 @exportObjectLiteralProperty ol.source.TiledWMSOptions.projection ol.Projection|undefined
 @exportObjectLiteralProperty ol.source.TiledWMSOptions.url string|undefined
diff --git a/src/ol/source/bingmapssource.js b/src/ol/source/bingmapssource.js
index 1e5355904c..729870b814 100644
--- a/src/ol/source/bingmapssource.js
+++ b/src/ol/source/bingmapssource.js
@@ -36,6 +36,7 @@ ol.BingMapsStyle = {
 ol.source.BingMaps = function(bingMapsOptions) {
 
   goog.base(this, {
+    opaque: true,
     projection: ol.projection.getFromCode('EPSG:3857')
   });
 
diff --git a/src/ol/source/debugtilesource.js b/src/ol/source/debugtilesource.js
index e553081ae3..d9ab21ad80 100644
--- a/src/ol/source/debugtilesource.js
+++ b/src/ol/source/debugtilesource.js
@@ -90,6 +90,7 @@ ol.source.DebugTileSource = function(options) {
 
   goog.base(this, {
     extent: options.extent,
+    opaque: false,
     projection: options.projection,
     tileGrid: options.tileGrid
   });
diff --git a/src/ol/source/imagetilesource.js b/src/ol/source/imagetilesource.js
index d47b9215e5..b29849a4a6 100644
--- a/src/ol/source/imagetilesource.js
+++ b/src/ol/source/imagetilesource.js
@@ -18,6 +18,7 @@ goog.require('ol.tilegrid.TileGrid');
  * @typedef {{attributions: (Array.<ol.Attribution>|undefined),
  *            crossOrigin: (null|string|undefined),
  *            extent: (ol.Extent|undefined),
+ *            opaque: (boolean|undefined),
  *            projection: (ol.Projection|undefined),
  *            tileGrid: (ol.tilegrid.TileGrid|undefined),
  *            tileUrlFunction: (ol.TileUrlFunctionType|undefined)}}
@@ -36,6 +37,7 @@ ol.source.ImageTileSource = function(options) {
   goog.base(this, {
     attributions: options.attributions,
     extent: options.extent,
+    opaque: options.opaque,
     projection: options.projection,
     tileGrid: options.tileGrid
   });
diff --git a/src/ol/source/mapquestsource.js b/src/ol/source/mapquestsource.js
index 08fb316632..ae12b33a25 100644
--- a/src/ol/source/mapquestsource.js
+++ b/src/ol/source/mapquestsource.js
@@ -26,6 +26,7 @@ ol.source.MapQuestOSM = function() {
 
   goog.base(this, {
     attributions: attributions,
+    opaque: true,
     maxZoom: 28,
     url: 'http://otile{1-4}.mqcdn.com/tiles/1.0.0/osm/{z}/{x}/{y}.jpg'
   });
@@ -54,6 +55,7 @@ ol.source.MapQuestOpenAerial = function() {
   goog.base(this, {
     attributions: attributions,
     maxZoom: 18,
+    opaque: true,
     url: 'http://oatile{1-4}.mqcdn.com/tiles/1.0.0/sat/{z}/{x}/{y}.jpg'
   });
 
diff --git a/src/ol/source/openstreetmapsource.js b/src/ol/source/openstreetmapsource.js
index 8bbfaf5742..258fe22637 100644
--- a/src/ol/source/openstreetmapsource.js
+++ b/src/ol/source/openstreetmapsource.js
@@ -18,6 +18,7 @@ ol.source.OpenStreetMap = function() {
 
   goog.base(this, {
     attributions: [attribution],
+    opaque: true,
     maxZoom: 18,
     url: 'http://{a-c}.tile.openstreetmap.org/{z}/{x}/{y}.png'
   });
diff --git a/src/ol/source/stamensource.js b/src/ol/source/stamensource.js
index 46f87d83df..90355bf1e5 100644
--- a/src/ol/source/stamensource.js
+++ b/src/ol/source/stamensource.js
@@ -85,6 +85,7 @@ ol.source.Stamen = function(stamenOptions) {
   goog.base(this, {
     attributions: [attribution],
     maxZoom: config.maxZoom,
+    opaque: false,
     url: 'http://{a-d}.tile.stamen.com/' + layer + '/{z}/{x}/{y}.' + config.type
   });
 
diff --git a/src/ol/source/tiledwmssource.js b/src/ol/source/tiledwmssource.js
index 9c7eb5ec8c..998cff4b43 100644
--- a/src/ol/source/tiledwmssource.js
+++ b/src/ol/source/tiledwmssource.js
@@ -27,6 +27,9 @@ ol.source.TiledWMS = function(tiledWMSOptions) {
   var extent = goog.isDef(tiledWMSOptions.extent) ?
       tiledWMSOptions.extent : projectionExtent;
 
+  var transparent = goog.isDef(tiledWMSOptions.transparent) ?
+      tiledWMSOptions.transparent : true;
+
   var version = goog.isDef(tiledWMSOptions.version) ?
       tiledWMSOptions.version : '1.3';
 
@@ -44,7 +47,7 @@ ol.source.TiledWMS = function(tiledWMSOptions) {
     'REQUEST': 'GetMap',
     'STYLES': '',
     'FORMAT': 'image/png',
-    'TRANSPARENT': true
+    'TRANSPARENT': transparent
   };
   baseParams[version >= '1.3' ? 'CRS' : 'SRS'] = projection.getCode();
   goog.object.extend(baseParams, tiledWMSOptions.params);
@@ -97,6 +100,7 @@ ol.source.TiledWMS = function(tiledWMSOptions) {
     crossOrigin: tiledWMSOptions.crossOrigin,
     extent: extent,
     tileGrid: tileGrid,
+    opaque: !transparent,
     projection: projection,
     tileUrlFunction: ol.TileUrlFunction.withTileCoordTransform(
         tileCoordTransform, tileUrlFunction)
diff --git a/src/ol/source/tilesource.js b/src/ol/source/tilesource.js
index c250951e7e..cb3a5a5133 100644
--- a/src/ol/source/tilesource.js
+++ b/src/ol/source/tilesource.js
@@ -15,6 +15,7 @@ goog.require('ol.tilegrid.TileGrid');
 /**
  * @typedef {{attributions: (Array.<ol.Attribution>|undefined),
  *            extent: (ol.Extent|undefined),
+ *            opaque: (boolean|undefined),
  *            projection: (ol.Projection|undefined),
  *            tileGrid: (ol.tilegrid.TileGrid|undefined)}}
  */
@@ -35,6 +36,13 @@ ol.source.TileSource = function(tileSourceOptions) {
     projection: tileSourceOptions.projection
   });
 
+  /**
+   * @private
+   * @type {boolean}
+   */
+  this.opaque_ = goog.isDef(tileSourceOptions.opaque) ?
+      tileSourceOptions.opaque : false;
+
   /**
    * @protected
    * @type {ol.tilegrid.TileGrid}
@@ -98,6 +106,14 @@ ol.source.TileSource.prototype.findLoadedTiles = function(loadedTilesByZ,
 };
 
 
+/**
+ * @return {boolean} Opaque.
+ */
+ol.source.TileSource.prototype.getOpaque = function() {
+  return this.opaque_;
+};
+
+
 /**
  * @inheritDoc
  */