"Flood release" of water from the dam will have little effect on archaeological sites within Glen Canyon itself, but may help prevent errosion of sites down stream of the dam.
From the Department of the Interior news release:
The U.S. Department of the Interior will trigger the first "high-flow experimental release" at Glen Canyon Dam since 2008 on Monday, November 19. The release is part of a new long-term protocol announced in May by Secretary of the Interior Ken Salazar to meet water and power needs, as well as to allow better conservation of sediment downstream, more targeted efforts to control non-native fish predation, and continued scientific experimentation, data collection, and monitoring to better address the important resources in the Colorado River below Glen Canyon Dam.
In cooperation with five Interior agencies, the upcoming release is designed to take full advantage of sediment deposited by Colorado River tributaries as a result of recent rainstorms and monsoons. Scientists have determined that the right conditions exist to conduct a high-flow release to benefit downstream resources, including camping beaches, sandbars, backwater habitats, riparian vegetation, and archeological sites.
Something is not right. This message is just to keep things from messing up down the road