EIS Perspective #1

   Yes, it is true, the preferred alternative for the Glen Canyon Dam draft environmental impact statement (eis) was modified for the final eis. Increased maximum flows and an increase in upramping have been added to the final document. These changes will allow for increased power marketability for electricity generated at Glen Canyon Dam. Yes, this does favor power resources, but the eis has to evaluate all resources affected by its alternatives. In addition to the operational changes in maximum flows and upramp rates, the Adaptive Management Program will include endangered fish research flows as requested by the U.S. Fish and Wildlife Service in its biological opinion. Reclamation will be requesting funds to expeditiously complete the needed studies to move forward with selective withdrawal structures at Glen Canyon Dam.

   The flow modifications to the preferred alternative include an increase from 20,000 to 25,000 cubic feet per second (cfs) maximum flow and an upramp increase from 2,500 to 4,000 cfs per hour. These changes were reviewed and agreed upon by the cooperating agencies, other interested parties, and the gces senior scientist and his advisory panel, made up of experts from each discipline currently conducting research in the Grand Canyon.

   On March 1, 1993, the gces senior scientist and the advisory group met to determine the potential impacts from these modifications. Their goal was to evaluate the original interim operating criteria recommendations made in April 1991, current interim operating criteria, data from the research period of June 1990 to July 1991, and other pertinent data collected during monitoring of the interim operations of Glen Canyon Dam. Their findings determined that there would be no significant impact to downstream resources if the maximum flow was raised to 25,000 cfs and the upramp to 4,000 cfs per hour.

   A consultation meeting, as required by the Grand Canyon Protection Act, was held on August 26, 1993, to discuss the proposal to change operations. This meeting was open to the cooperating agencies, power interests, recreation and environmental groups, and the general public. An entire morning session was dedicated to the discussion of impacts to natural resources, economic resources, and compliance with the National Environmental Policy Act. The gces senior scientist presented data concluding that resource impacts to aquatic resources would be minimal to none below the Lees Ferry reach, and there may be some slight impacts during maximum flow releases above Lees Ferry.

   The scientists concluded that increasing the maximum releases to 25,000 cfs may provide for benefits to some Grand Canyon resources. Riparian vegetation would likely benefit from the infrequent inundation by the 25,000 cfs maximums. This flooding may encourage growth of mature vegetation and may also benefit young seedlings. During moderate and high volume months, the more frequent higher maximum flows could rebuild beaches to higher elevations, create and maintain backwater habitats for young native fishes, and reduce financial impacts to power consumers.

   The maximum flows under this new preferred alternative will rarely be used because of monthly release volumes dictated by the Annual Operating Plan and maximum daily fluctuating constraints. During minimum release years (8.23 million acre-feet), flows are expected to exceed 20,000 cfs less than 1 percent of the time. These minimum release years may occur 50 percent of the time. Only during months with release volumes between .9 and 1.5 million acre-feet will the maximum release exceed 20,000 cfs. With monthly release volumes greater than 1.5 million acre-feet, the flows would be steady at 25,000 cfs or more, regardless of the alternative chosen. Simply put, in only 3 of the past 38 months of interim operations have the flows exceeded .9 million acre-feet, with no months over .925 million acre-feet.

   Reclamation has produced a computer model that is very user friendly (even Shane can run it by himself), to demonstrate how infrequently the 25,000 maximum will actually be reached. It includes input variable like monthly release volumes, lake elevation, max and min flows, ramp rates etc. I have worked with this program and found flows over 20,000 cfs occur infrequently and flows of 25,000 cfs very rarely. This model is available for viewing at the gcrg office for anyone interested. 

   With the small amount of time that the maximum flows would actually be released under the preferred alternative, no measurable difference in impacts would be realized from the original preferred alternative in the draft eis which did not contain these increases.

   No impacts from increasing upramps to 4,000 cfs per hour have been identified by the researchers working in the Grand Canyon.

Bill Leibfried