Grand Canyon, October & November Colorado River Flows and High Flow Experiment Possible in November
This is a September 28, 2018, update from Heather Patno at Glen Canyon Dam.
This directive confirms that the release volume from Glen Canyon Dam for October, 2018, shall be 625,000 acre-feet. Hourly releases during weekdays in October, 2018, will fluctuate from a low of approximately 7,070 cfs during the early morning hours to a high of 12,700 cfs during the afternoon and evening hours. On weekend days in October, 2018, releases will fluctuate from a low of approximately 7,070 cfs during the early morning hours to a high of 11,900 cfs during the afternoon and evening hours.
The anticipated release volume for November 2018 is 625,000 kaf.
The Department of the Interior is exploring the possibility of a High Flow Experiment from Glen Canyon Dam to be conducted in November, 2018. High Flow Experiments (HFE) below Glen Canyon Dam are driven by weather, sediment inputs, and other resource conditions, in accordance with the Long-Term Experimental and Management Plan (LTEMP).
When sediment conditions during the summer and fall meet specific thresholds as described in the LTEMP, a fall HFE can occur. Fall HFEs can be scheduled to occur anytime during the months of October and November; however, under the LTEMP, HFEs have historically always occurred in November. Our best preliminary data and model runs indicate we now have enough sediment input from the Paria River for an HFE to occur at Glen Canyon Dam. The HFE Technical Team will be meeting to begin planning for a possible HFE and reviewing the status of resources and potential resource impacts.
The HFE will likely begin on November 5, 2018. The duration of the HFE is dependent upon further data collection, modeling, and analysis prior to the end of October. A final determination on the timing, magnitude and duration of a potential fall 2018 HFE will likely be made in mid- to late-October.
Heather E. Patno
Hydraulic Engineer, Glen Canyon Dam
Bureau of Reclamation