In 1996, the flow of the Colorado River through Grand Canyon was artificially elevated as part of an ongoing study to determine the downstream effects of the Glen Canyon Dam. In the pre-dam era, spring floods were the norm, and fed by snowmelt in the Rockies.
Though far from submerging the canyon (other than the muddying of the river the spike flow was almost imperceptible to the untrained eye), the 1996 experiment did replenish the sand on eroded beaches, re-bury (and thus protect) sensitive archaeological sites, clear backwater spawning areas for fish, and strip away non-native plants. A similar high flow in 2004 had similar beneficial effects.
Pending an environmental assessment due in February, a third high flow experiment will be conducted in March of 2008. The river level will double to more than 40,000 cubic feet per second for a several days. To read more about this exciting resource management endeavor, follow these links:
News Release (PDF – 28KB)