Natural Resources Conservation Service has changed the style of the map. Instead of shading in drainages and sub-drainages, now it looks as though they are color-keying the individual measurement stations.* Click image for a larger view.
You can view previous winters' maps here. For Colorado, links to individual SNOTEL stations are here.
* Official explanation: "Due to data system changes and resource
constraints, basin-filled maps for SNOTEL & Snow Course Snow Water Equivalent
are no longer being produced and are replaced by point maps."