This draft environmental impact statement (EIS) analyzes the impacts of operations from 1963 to 1990 (baseline conditions) and alternative operations of Glen Canyon Dam on downstream environmental and cultural resources of Glen and Grand Canyons. Alternative operations evaluated include three that would provide steady flows; three that would provide various levels of fluctuating flows; and two, including no action, that would provide unrestricted fluctuating flows. Additional measures have been combined with the alternative operations, where appropriate, to provide additional resource protection or enhancement. The preferred alternative is the Modified Low Fluctuating Flow Alternative.
United States Department of the Interior, "Operation of Glen Canyon Dam, Draft Environmental Impact Statement" (1993). All U.S. Government Documents (Utah Regional Depository). Paper 305.