The Biological Opinion (BO) dated 21 December 1994 was in response to USBR’s request for section 7 consultation under the Endangered Species Act “on the proposed action to operate Glen Canyon Dam according to … the Modified Low Fluctuating Flow Altemative (MLFF)” (USFWS, 1994). The modified-low-fluctuating-flow strategy allowed dam operators to continue diurnal fluctuations of water flow through the dam’s turbines to meet power demand, but restricted the up-ramp and down-ramp rates of water discharge to reduce the rapidity of river flow changes and the total daily range of fluctuations in river flow. The BO determined that a MLFF would not result in jeopardy to endangered species.