The Death of a River

  As I have already said, the Colorado River, when it flows past Yuma, is but a pittance of what it once was. The river is 1,450 miles long if you measure from its official source high in the Never Summer Range in Rocky Mountain National Park, north of Denver, Colorado. If you measure from the river's actual source, the head of the Green River in the Wind River Mountains of central Wyoming, it is over 1,700 miles long. The definition of the beginning of a river is the most distant source, which means the Green River in this case. This makes the Colorado one of the longest rivers in the United States and the world. For most of its lower length, it is still a big river. That being said, it is still not as big as it once was. It is one of the most over-allocated rivers in the world, quenching the thirst of a dry land that has a far bigger population than it can support. When the waters of the Colorado were divided up between the various states that it flows through, it was an unusually rainy year--1927. The river has not had that much water in it since! As a result, the Colorado no longer reaches the Sea of Cortez. It has one of the biggest deltas in the world and yet the delta is usually dry. The only time there is water in the lower reaches of the river is either in unusually wet years or when tidewater from the Sea of Cortez makes its way up the myriad of sunbaked channels at the river's mouth.
  Yuma was once extremely prone to flooding because of two things. It was at the confluence of the Colorado and Gila Rivers and also because of a phenomenon called the
tidal bore. A tidal bore occurred when the powerful current of the Colorado, augmented by the once powerful flow of the Gila River, collided head on with tidewater from the Sea of Cortez. This phenomenon created a huge wall of water that spread out over the surrounding desert and inundated everything in its path. Well, since the Gila River is now dry and the Colorado is now a mere rivulet compared to what it once was, the tidal bore is no longer an issue. 
  The fact that Yuma, one of the driest cities in the world, is no longer flood prone might sound like good news, but it is actually terrible news. It is the result of the destruction of what famed naturalist Aldo Leopold described as a "milk and honey wilderness" in his masterwork 
The Sand County Almanac.    
  I will describe in more detail the destruction of this once great waterway in the next few installments of this blog.