The 2023 Spring HFE - Revision history

Cellsworth at 16:56, 20 October 2025

2025-10-20T16:56:05Z

Cellsworth at 16:54, 20 October 2025

2025-10-20T16:54:52Z

Cellsworth at 20:00, 16 October 2025

2025-10-16T20:00:44Z

Cellsworth at 16:07, 8 December 2023

2023-12-08T16:07:09Z

Cellsworth at 16:06, 8 December 2023

2023-12-08T16:06:07Z

Cellsworth at 15:59, 8 December 2023

2023-12-08T15:59:12Z

Cellsworth at 15:58, 8 December 2023

2023-12-08T15:58:18Z

Cellsworth at 22:28, 7 December 2023

2023-12-07T22:28:48Z

Cellsworth at 22:20, 7 December 2023

2023-12-07T22:20:21Z

Cellsworth at 21:38, 7 December 2023

2023-12-07T21:38:03Z

@@ Line 90: / Line 90: @@
 '''Costs'''
-*Estimated costs to hydropower: '''$1.4M'''
+*Estimated costs to hydropower: $1.4M
 *Actual costs to hydropower: [https://www.osti.gov/biblio/2587205 '''$1.33M''']
 *Direct expenses for removal of concession assets: TBD

@@ Line 91: / Line 91: @@
 '''Costs'''
 *Estimated costs to hydropower: '''$1.4M'''
-*Actual costs to hydropower: TBD
+*Actual costs to hydropower: [https://www.osti.gov/biblio/2587205 '''$1.33M''']
 *Direct expenses for removal of concession assets: TBD

@@ Line 162: / Line 162: @@
 *[[Media:2 Final Technical Report and Recommendation Regarding a Spring Flow Experiment at Glen Canyon Dam, April 2023 (1).pdf| Final Technical Report and Recommendation Regarding a Spring Flow Experiment at Glen Canyon Dam, April 2023 ]]
 *[[Media:3 Spring 2023 Memorandum SIR.pdf| Reevaluation of the 2016 Long-term Experimental and Management Plan Final Environmental Impact Statement (LTEMP FEIS) and Record of Decision (ROD) for the 2023 Spring Flow Experiment (2023 April Experiment) ]]
 == COMPLIANCE ==

@@ Line 53: / Line 53: @@
 In summary, there is a significant opportunity to take advantage of the last two years of significant Paria sand inputs to rebuild sandbars in the Colorado River downstream of Glen Canyon Dam with an HFE. As a result of high sediment inputs from both the Paria and the LCR, sediment conditions are currently ideal for rebuilding sandbars via an HFE. However, this opportunity is time-limited: if high dam releases occur as expected this spring into the summer, these will begin to export a significant fraction of the sand currently present in the system. By next Fall, much or all the sand supplied over the last two years could have been exported to lake Mead.
-The opportunity to use some of this sand to rebuild sandbars will not persist indefinitely, which is similar in principle to the motivation for including the Proactive Spring HFE in the LTEMP. The intent of the Proactive Spring HFE in the LTEMP protocol was designed for the following, “…proactive spring flows [are] designed to "park' sediment before summer flows in high annual volume years.” In addition, the LTEMP ROD states that, ‘if it is determined that a sediment-triggered HFE cannot be implemented and the projected annual volume is greater than or equal to 10 maf, a proactive spring HFE will be triggered.” The following information suggests that current conditions are similar in principle to a high annual volume year that would trigger a Proactive Spring HFE. The latest runoff forecast suggests that 9.5 maf may need to be released in Water Year 2023, of which, 523 kaf that was intentionally withheld from release early in the water year to maintain Lake Powell water surface elevations must be released in the remaining months of the water year. Additionally, WY2023 started out with low monthly volumes because it was projected as a 7.0 maf release year, but now balancing releases of 9.0 to 9.5 maf year are projected. To ensure releases are achieved before the end of the water year, monthly volumes for the rest of the water year will be as high or higher than those during equalization years ≥10 maf. The necessity to move this water by the end of Water Year 2023 is also addressed in the Grand Canyon Protection Act (GCPA), Section 1802(b), providing that Glen Canyon Dam actions and operations must be fully compliant with the Law of the River. Therefore, the projected releases and unusual water conditions allow the consideration of an HFE to remain within the scope of the GCPA, as the projected water will need to be released with or without a potential HFE. [[Media:2 Final Technical Report and Recommendation Regarding a Spring Flow Experiment at Glen Canyon Dam, April 2023 (1).pdf]]
+The opportunity to use some of this sand to rebuild sandbars will not persist indefinitely, which is similar in principle to the motivation for including the Proactive Spring HFE in the LTEMP. The intent of the Proactive Spring HFE in the LTEMP protocol was designed for the following, “…proactive spring flows [are] designed to "park' sediment before summer flows in high annual volume years.” In addition, the LTEMP ROD states that, ‘if it is determined that a sediment-triggered HFE cannot be implemented and the projected annual volume is greater than or equal to 10 maf, a proactive spring HFE will be triggered.” The following information suggests that current conditions are similar in principle to a high annual volume year that would trigger a Proactive Spring HFE. The latest runoff forecast suggests that 9.5 maf may need to be released in Water Year 2023, of which, 523 kaf that was intentionally withheld from release early in the water year to maintain Lake Powell water surface elevations must be released in the remaining months of the water year. Additionally, WY2023 started out with low monthly volumes because it was projected as a 7.0 maf release year, but now balancing releases of 9.0 to 9.5 maf year are projected. To ensure releases are achieved before the end of the water year, monthly volumes for the rest of the water year will be as high or higher than those during equalization years ≥10 maf. The necessity to move this water by the end of Water Year 2023 is also addressed in the Grand Canyon Protection Act (GCPA), Section 1802(b), providing that Glen Canyon Dam actions and operations must be fully compliant with the Law of the River. Therefore, the projected releases and unusual water conditions allow the consideration of an HFE to remain within the scope of the GCPA, as the projected water will need to be released with or without a potential HFE. [[Media:2 Final Technical Report and Recommendation Regarding a Spring Flow Experiment at Glen Canyon Dam, April 2023 (1).pdf | (1)]]
 ==HFE Details==
@@ Line 154: / Line 154: @@
 *This support applies to Water Year 2023, and only to the extent that the experiment is within the scope and authority of the LTEMP ROD.
-Based on the identification of high resource benefits by both the PI Technical and Leadership Teams, the determination of no unacceptable adverse impacts, and majority recommendation for the Department to implement a 72-hr duration Spring 2023 Experiment, I concur with the determination, and I have decided to conduct a Spring Experiment for 72-hrs of peak duration beginning on April 24.  We will continue to work with our partners on future experimental flows and in the protection of the Grand Canyon and our most important resources. [[Media:1 Spring 2023 HFE - Decision Memo.pdf]]
+Based on the identification of high resource benefits by both the PI Technical and Leadership Teams, the determination of no unacceptable adverse impacts, and majority recommendation for the Department to implement a 72-hr duration Spring 2023 Experiment, I concur with the determination, and I have decided to conduct a Spring Experiment for 72-hrs of peak duration beginning on April 24.  We will continue to work with our partners on future experimental flows and in the protection of the Grand Canyon and our most important resources. [[Media:1 Spring 2023 HFE - Decision Memo.pdf | (2)]]

@@ Line 53: / Line 53: @@
 In summary, there is a significant opportunity to take advantage of the last two years of significant Paria sand inputs to rebuild sandbars in the Colorado River downstream of Glen Canyon Dam with an HFE. As a result of high sediment inputs from both the Paria and the LCR, sediment conditions are currently ideal for rebuilding sandbars via an HFE. However, this opportunity is time-limited: if high dam releases occur as expected this spring into the summer, these will begin to export a significant fraction of the sand currently present in the system. By next Fall, much or all the sand supplied over the last two years could have been exported to lake Mead.
-The opportunity to use some of this sand to rebuild sandbars will not persist indefinitely, which is similar in principle to the motivation for including the Proactive Spring HFE in the LTEMP. The intent of the Proactive Spring HFE in the LTEMP protocol was designed for the following, “…proactive spring flows [are] designed to "park' sediment before summer flows in high annual volume years.” In addition, the LTEMP ROD states that, ‘if it is determined that a sediment-triggered HFE cannot be implemented and the projected annual volume is greater than or equal to 10 maf, a proactive spring HFE will be triggered.” The following information suggests that current conditions are similar in principle to a high annual volume year that would trigger a Proactive Spring HFE. The latest runoff forecast suggests that 9.5 maf may need to be released in Water Year 2023, of which, 523 kaf that was intentionally withheld from release early in the water year to maintain Lake Powell water surface elevations must be released in the remaining months of the water year. Additionally, WY2023 started out with low monthly volumes because it was projected as a 7.0 maf release year, but now balancing releases of 9.0 to 9.5 maf year are projected. To ensure releases are achieved before the end of the water year, monthly volumes for the rest of the water year will be as high or higher than those during equalization years ≥10 maf. The necessity to move this water by the end of Water Year 2023 is also addressed in the Grand Canyon Protection Act (GCPA), Section 1802(b), providing that Glen Canyon Dam actions and operations must be fully compliant with the Law of the River. Therefore, the projected releases and unusual water conditions allow the consideration of an HFE to remain within the scope of the GCPA, as the projected water will need to be released with or without a potential HFE.
+The opportunity to use some of this sand to rebuild sandbars will not persist indefinitely, which is similar in principle to the motivation for including the Proactive Spring HFE in the LTEMP. The intent of the Proactive Spring HFE in the LTEMP protocol was designed for the following, “…proactive spring flows [are] designed to "park' sediment before summer flows in high annual volume years.” In addition, the LTEMP ROD states that, ‘if it is determined that a sediment-triggered HFE cannot be implemented and the projected annual volume is greater than or equal to 10 maf, a proactive spring HFE will be triggered.” The following information suggests that current conditions are similar in principle to a high annual volume year that would trigger a Proactive Spring HFE. The latest runoff forecast suggests that 9.5 maf may need to be released in Water Year 2023, of which, 523 kaf that was intentionally withheld from release early in the water year to maintain Lake Powell water surface elevations must be released in the remaining months of the water year. Additionally, WY2023 started out with low monthly volumes because it was projected as a 7.0 maf release year, but now balancing releases of 9.0 to 9.5 maf year are projected. To ensure releases are achieved before the end of the water year, monthly volumes for the rest of the water year will be as high or higher than those during equalization years ≥10 maf. The necessity to move this water by the end of Water Year 2023 is also addressed in the Grand Canyon Protection Act (GCPA), Section 1802(b), providing that Glen Canyon Dam actions and operations must be fully compliant with the Law of the River. Therefore, the projected releases and unusual water conditions allow the consideration of an HFE to remain within the scope of the GCPA, as the projected water will need to be released with or without a potential HFE. [[Media:2 Final Technical Report and Recommendation Regarding a Spring Flow Experiment at Glen Canyon Dam, April 2023 (1).pdf]]
 ==HFE Details==
@@ Line 154: / Line 154: @@
 *This support applies to Water Year 2023, and only to the extent that the experiment is within the scope and authority of the LTEMP ROD.
-Based on the identification of high resource benefits by both the PI Technical and Leadership Teams, the determination of no unacceptable adverse impacts, and majority recommendation for the Department to implement a 72-hr duration Spring 2023 Experiment, I concur with the determination, and I have decided to conduct a Spring Experiment for 72-hrs of peak duration beginning on April 24.  We will continue to work with our partners on future experimental flows and in the protection of the Grand Canyon and our most important resources.
+Based on the identification of high resource benefits by both the PI Technical and Leadership Teams, the determination of no unacceptable adverse impacts, and majority recommendation for the Department to implement a 72-hr duration Spring 2023 Experiment, I concur with the determination, and I have decided to conduct a Spring Experiment for 72-hrs of peak duration beginning on April 24.  We will continue to work with our partners on future experimental flows and in the protection of the Grand Canyon and our most important resources. [[Media:1 Spring 2023 HFE - Decision Memo.pdf]]
 == SUPPORTING DOCUMENTS ==

@@ Line 18: / Line 18: @@
 '''Spring Accounting Period''' [[File:PariaRiver2021 2023.png|thumb|right|400px|[http://www.gcmrc.gov/discharge_qw_sediment/station/GCDAMP/09382000#/ '''Paria River gage at Lees Ferry'''] ]]
-*Paria input (July 1, 2022 and March 1, 2023): +3,156,702 mt
+*Paria input (July 1, 2021 and March 1, 2023): +3,156,702 mt
-*Accumulated in Upper Marble Canyon (July 1, 2022 and March 1, 2023, lower bound) = +1,991,672 mt
+*Accumulated in Upper Marble Canyon (July 1, 2021 and March 1, 2023, lower bound) = +1,991,672 mt
-*Accumulated in Lower Marble Canyon (July 1, 2022 and March 1, 2023, lower bound) = +591,214 mt
+*Accumulated in Lower Marble Canyon (July 1, 2021 and March 1, 2023, lower bound) = +591,214 mt
 *Available for Spring HFE: 1,991,672 + 591,214 mt = 2,582,886 mt

@@ Line 21: / Line 21: @@
 *Accumulated in Upper Marble Canyon (November 2018 and March 1, 2023, lower bound) = +1,991,672 mt
 *Accumulated in Lower Marble Canyon (November 2018 and March 1, 2023, lower bound) = +591,214 mt
-*Available for Spring HFE: xx mt
+*Available for Spring HFE: 1,991,672 + 591,214 mt = 2,582,886 mt
 '''HFE Transport''' [[File:UpperMarble2021 2023.png|thumb|right|400px|[http://www.gcmrc.gov/discharge_qw_sediment/reach/GCDAMP/09380000/09383050 '''Upper Marble Canyon'''] ]]
-*Paria input (April 24 - 27): xx
+*Paria input (April 24 - 27): 380 mt
-*Evacuated from Upper Marble Canyon (April 24 - 27, lower bound) = xx
+*Evacuated from Upper Marble Canyon (April 24 - 27, lower bound) = -751,108 mt
-*Evacuated from Lower Marble Canyon (April 24 - 27, lower bound) = xx
+*Evacuated from Lower Marble Canyon (April 24 - 27, lower bound) = -132,436 mt
-*Left over in Marble Canyon after HFE (April 24 - 27): xx + xx - xx - xx = xx
+*Left over in Marble Canyon after HFE (April 24 - 27): 2,582,886 + 380 - 751,108 - 132,436 = 1,699,722 mt
 [[File:LowerMarble2021 2023.png|thumb|right|400px|[http://www.gcmrc.gov/discharge_qw_sediment/reach/GCDAMP/09383050/09383100 '''Lower Marble Canyon'''] ]]

@@ Line 71: / Line 71: @@
 '''Ramp Rates'''
-*Ramp up: 4,000 cfs/hr from 6,500 - 23,100 cfs, then 3,750 cfs/hr to peak (38,100 cfs)
+*Ramp up: 4,000 cfs/hr from 6,500 - 23,100 cfs, then 3,750 cfs/hr to peak (39,500 cfs)
 *Ramp down: 1,875 cfs/hr from 38,100 – 23,100 cfs, then 2,500 cfs/hr to 9,000 cfs