DiamondFork River, Utah has been used since 1915 to conveyirrigation water from the Colorado River basin to areas alongthe Wasatch Front. These flows have increased summer base flowsmore than 10 times above natural levels and led todramatic changes in channel and floodplain morphology. In 1939, DiamondFork was a meandering, single-thread channel averaging 12 m inwidth. By 1952, the lower 6 km of the channelwas braided, occupying the entire 150 m-wide valley floor. Concurrentwith changes in floodplain morphology, there has been a 50to 90 per cent reduction in the extent of ripariancottonwood forest. The remaining forest is dominated by late maturecottonwoods, with little survival into premature (2?7 yr) and earlymature (8?30 yr) age [...]