A River Trickles Through It

Nearly half of all river miles in the American West no longer exist in their natural state. Instead they have been dammed & diverted, or affected by some other form of human development. You can see for yourself where rivers in the West have been altered from their natural state on the Disappearing Rivers interactive map.

On this interactive map, built by Gage Cartographics, all rivers in the American West are colored to show the degree by which they have been altered by humans. If you click on an individual river on the map you can view the percentage degree by which the river has been altered (in that segment of the river and over its whole length). The menu in the top right corner of the map allows you to also view the degree by which all flood plains have been affected by human development across the American West. 

The Disappearing Rivers map also includes a guided tour of the Colorado River, exploring in more detail how human development has altered this mighty river. More than half (54%) of the Colorado River has been dammed, diverted or otherwise altered from its natural state. The guided tour highlights how human developments (such as urbanization and agriculture) have impacted on the Colorado River. The tour also explores where conservation efforts have been made to help restore the natural health of the Colorado. 

A number of other amazing interactive maps can help you explore American rivers even more closely. For example River Runner is a fascinating map tool which uses U.S. watershed data to calculate the route that a drop of rain would take from any location in the United States to the ocean. The map uses information about America's river watersheds to create an animated map which visualizes the journey downstream from any location in the contiguous United States.

Click anywhere on River Runner's map of the United States and you can discover the path that a drop of water would take from that location to the distant ocean (although sometimes the final destination may be the Great Lakes or another large inland water feature). A small inset map will reveal the path that leads downstream from your selected location to the sea. The main larger map actually animates the route of this journey on top of America's 3D terrain. 

If you are interested in America's watersheds then you might also enjoy the USGS's Streamer map. The Streamer map allows you to trace rivers or streams upstream to their source or downstream to their final destinations in the USA. This interactive map can create very dramatic visualizations of river watersheds, particularly when you trace a river upstream to show all of its tributaries.

FernLeaf Interactive has also created an interactive map which allows you to view over 100,000 watershed regions. The Watersheds Map shows the topological relationships between the USGS level 12 hydrologic units for the entire United States.

This map allows you to visualize watershed regions throughout the USA. As you mouse-over the map it automatically updates to show upstream areas in red and downstream areas in blue. You can click on the map at anytime to freeze the map view (click on the map again to unfreeze & re-enable the dynamic loading of the watershed data).