The south-western US is suffering its eighth year of drought. There are concerns that the Colorado River can no longer meet the needs of the tens of millions of people living in major cities like Las Vegas and Los Angeles.
The Colorado River starts in the snowy peaks of the Rocky Mountains to the north. It travels through the south-western states, towards Mexico and the Pacific ocean.
Two dams were built along the river in the last century. They have caused changes to the plant and animal life of the river.
The lakes behind the dams supply water to agriculture, to industry and to many homes in huge sprawling cities like Las Vegas and Los Angeles. They are simply using too much water.
So too is some of the vegetation along the river. Tamarisk trees - otherwise known as salt-cedars. They drink a tremendous amount. This adds to the problem of water, as now we have our fresh water source being sucked dry by these trees.
Read more and watch a video from the BBC on this topic here.
Great for Higher and Int 2 River Basin Management.