Grand Canyon flood goes ahead

Forest and Bird, Issue 280, 1 May 1996, Page 10

Grand Canyon flood goes ahead

IN LATE MARCH, US Interior Secretary Bruce Babbitt triggered the opening of gates on the 220-metre-tall Hoover dam on the Colorado River, sending water streaming into the Grand Canyon in an attempt to restore parts of the canyon’s damaged natural environment. The dam’s opening represented a decision to recreate a periodic disturbance in the ecosystem by simulating the natural spring flood (see Forest e Bird, August 1995, page 10). For 34 years the dam has altered the hydrology of the canyon and taken its toll on the unique desert ecology. The March "flood" deposited nutrient-rich sediment along the sides of the canyon, and recreated sandbars, beaches and back water channels, helping to

rebuild spawning areas and habitat for humpback chub and endangered local fish. Scientists saw no loss of fish as a result of the flooding and no harm to bald eagles or peregrine falcons. Nesting trees of the south-west willow flycatcher were safe, although they were in the flooded areas, and archeological sites were also unharmed. The flood cost an estimated $4.3 million as water levels in the dam dropped by over a metre. The dam provides electricity and water for 15 million people in eight southwestern states. "From all indications, the test flooding has worked brilliantly," said Babbitt. He said the lessons learned at the canyon set a "powerful precedent" that could be applied in such areas at the Florida Everglades and Washington’s Columbia River.