TCD Learning Page - Revision history

Cellsworth at 14:50, 14 October 2026

2026-10-14T14:50:44Z

Cellsworth at 20:19, 13 October 2026

2026-10-13T20:19:22Z

Cellsworth at 15:42, 13 October 2026

2026-10-13T15:42:26Z

Cellsworth at 15:32, 13 October 2026

2026-10-13T15:32:27Z

Cellsworth at 14:51, 18 August 2026

2026-08-18T14:51:39Z

Cellsworth at 20:00, 31 October 2025

2025-10-31T20:00:51Z

Cellsworth at 23:02, 23 October 2025

2025-10-23T23:02:10Z

Cellsworth at 01:14, 23 October 2025

2025-10-23T01:14:49Z

Cellsworth at 21:20, 22 October 2025

2025-10-22T21:20:10Z

Cellsworth at 20:46, 22 October 2025

2025-10-22T20:46:36Z

@@ Line 124: / Line 124: @@
 '''2024'''
-*[[Media:Glen_Canyon_Fish_Escapement_Appraisal_Report_05.2024_FINAL.pdf | Glen Canyon Fish Escapement Appraisal Report (Final)]]
+*[[Media:Glen_Canyon_Fish_Escapement_Appraisal_Report_05.2024_FINAL.pdf | Wagner and Svoboda. 2024. Glen Canyon Fish Escapement Appraisal Report (Final)]]
 *[https://www.usbr.gov/uc/progact/amp/twg/2024-10-30-twg-meeting/20241030-HydroacousticThermalCurtainUpdate-508-AMWQD.pdf Hydroacoustic and Thermal Curtain Update]
 *[https://www.usbr.gov/uc/progact/amp/twg/2024-01-25-twg-meeting/20240125-TWGMeeting-ThermalCurtainExclusionNet-508-UCRO.pdf Thermal Curtain/Exclusion Net ]

@@ Line 124: / Line 124: @@
 '''2024'''
 *[https://www.usbr.gov/uc/progact/amp/twg/2024-10-30-twg-meeting/20241030-HydroacousticThermalCurtainUpdate-508-AMWQD.pdf Hydroacoustic and Thermal Curtain Update]
 *[https://www.usbr.gov/uc/progact/amp/twg/2024-01-25-twg-meeting/20240125-TWGMeeting-ThermalCurtainExclusionNet-508-UCRO.pdf Thermal Curtain/Exclusion Net ]

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 '''Phase 1: A Warm-Water Temperature Control Device (TCD)'''
-*1997:  Value Planning Study (Reclamation 1997a)
+*1997: Value Planning Study (Reclamation 1997a)
-*1997:  Feasibility Study (Reclamation 1997b)
+*1997: Feasibility Study (Reclamation 1997b)
-*1999:  Draft Environmental Assessment (Reclamation 1999)
+*1999: Draft Environmental Assessment (Reclamation 1999)
-*1999:  Physical Model Study (Vermeyen 1999)
+*1999: Physical Model Study (Vermeyen 1999)
 *2000-2004:  Reservoir Modeling of Selective Withdrawal Options (Cole and Wells 2003)
-*2003:  Survey of Selective Withdrawal Systems (Vermeyen et al 2003)
+*2003: Survey of Selective Withdrawal Systems (Vermeyen et al 2003)
 *2004-2006: Feasibility Studies to investigate a wider range of withdrawal capacity.
-*2005:  Economics of TCD Operation on Hydropower Revenues
+*2005: Economics of TCD Operation on Hydropower Revenues
-*2006:  Value Engineering Study
+*2006: Value Engineering Study
-*2006:  Constructability Review (Reclamation 2006a)
+*2006: Constructability Review (Reclamation 2006a)
-*2006:  Design, Estimating and Construction Review
+*2006: Design, Estimating and Construction Review
 *2006-2007:  Final Design (Reclamation 2007)
 *2008:  USFWS Biological Opinion identified concerns with nonnative fish expansion and having a TCD that could only release warm water (USFWS 2008)
 '''Phase 2: A Warm/Cold-Water TCD That Also Reduces Fish Entrainment'''
-*2016:  LTEMP EIS Biological Opinion - Reclamation to explore efficacy of TCD and means to prevent fish passage (USFWS 2016)
+*2016: LTEMP EIS Biological Opinion - Reclamation to explore efficacy of TCD and means to prevent fish passage (USFWS 2016)
-*2020:  Review of Temperature Control Options for Reservoir Release Flows (Svoboda, 2020)
+*2020: Review of Temperature Control Options for Reservoir Release Flows (Svoboda, 2020)
-*2020:  Technology Search to seek all ways that water temperature is controlled in any industry that may be applicable to dams (yet2 2020)
+*2020: Technology Search to seek all ways that water temperature is controlled in any industry that may be applicable to dams (yet2 2020)
-*2022:  Glen Canyon Dam Fish Escapement Options (Svoboda, 2022)
+*2022: Glen Canyon Dam Fish Escapement Options (Svoboda, 2022)
 *2022-2024: USU Entrainment Study
-*2024:  Glen Canyon Dam Fish Escapement Appraisal Study (Wagner and Svoboda 2024)
+*2024: Glen Canyon Dam Fish Escapement Appraisal Study (Wagner and Svoboda 2024)
-*2024:  LTEMP SEIS – includes flow options for using bypass to cool river below Glen Canyon Dam (Reclamation 2024)
+*2024: LTEMP SEIS – includes flow options for using bypass to cool river below Glen Canyon Dam
 *2024: Value Planning Study
 *2024-2025: PNNL Biofouling Study
+*2026-2028: RCS evaluation of a thermal curtain (DOE grant)
----- This is where we currently are ----
+*End of year 2029: Reclamation completes an Appraisal Level Design of a thermal curtain in the forebay and a temperature control device on Glen Canyon Dam (Post-2026 BiOp)
-−
-−
 |-

@@ Line 178: / Line 178: @@
 ---- This is where we currently are ----
-*2024: Selection of a preferred method to provide both warm and cool release temperatures and reduce fish entrainment
-*2025: Hydrologic modeling
-*2025: Compliance (NEPA, ESA, Section 106)
-*2026: Design Level Study
-*2027: Construction and installation
-*2028-2031: Post construction monitoring
 |-

@@ Line 70: / Line 70: @@
 [[Image:Thermal Curtain warmwater.png|thumb|center|400px|A thermal curtain configured to warm dam releases]]
-=='''Selective Withdrawal Structure (TCD)''' ==
+=='''Temperature Control Device (TCD)''' ==
 Examples: Flaming Gorge Dam, Shasta Dam, Folsom Dam, Jordanelle Dam, Hungry Horse Dam, Cougar Dam, Applegate Lake.

@@ Line 81: / Line 81: @@
 =='''Destratification: (Bubblers, Pumps, etc.)'''==
-Mixing thermal strata in the GCD forebay that results in substantial cooling during times of otherwise warm water releases (typically summer through fall) is likely to reduce or eliminate smallmouth bass spawning in the mainstem Colorado River below the dam. Also, mixing thermal strata in the GCD forebay and cooling the water would likely reduce the number of warmwater nonnative fish present in the forebay, including smallmouth bass. Smallmouth bass would likely move out of the area to seek warmer waters (Carter et al., 2012) such as the shallow, littoral habitat found in nearby Wahweap Bay.
+Mixing thermal strata in the Glen Canyon Dam forebay that results in substantial cooling during times of otherwise warm water releases (typically summer through fall) is likely to reduce or eliminate smallmouth bass spawning in the mainstem Colorado River below the dam. Also, mixing thermal strata in the Glen Canyon Dam forebay and cooling the water would likely reduce the number of warmwater nonnative fish present in the forebay, including smallmouth bass. Smallmouth bass would likely move out of the area to seek warmer waters (Carter et al., 2012) such as the shallow, littoral habitat found in nearby Wahweap Bay.
 [[Image:BubblePlume.jpg|thumb|center|400px|Depiction of a bubble plume destratifying the forebay at Glen Canyon Dam]]
@@ Line 95: / Line 95: @@
 =='''[https://gcdamp.com/index.php/SEIS_Bypass_Releases Bypass]'''==
-This is a continuation of current operations at Glen Canyon Dam (GCD) developed as part of the Smallmouth Bass Supplemental Environmental Impact Statement (SEIS). The SEIS was finalized in June of 2024 and the Record of Decision was signed and implemented in July 2024. There are 5 possible options for GCD releases to keep water temperatures at river mile 61 in Grand Canyon at or below 15.5°C. For a more complete summary and discussion of flow alternatives, please refer to the Final SEIS (Bureau of Reclamation, 2024) or see the [https://gcdamp.com/index.php/SEIS_Bypass_Releases the page for the SEIS Bypass Releases].
+This is a continuation of current operations at Glen Canyon Dam developed as part of the Smallmouth Bass Supplemental Environmental Impact Statement (SEIS). The SEIS was finalized in June of 2024 and the Record of Decision was signed and implemented in July 2024. There are 5 possible options for Glen Canyon Dam releases to keep water temperatures at river mile 61 in Grand Canyon at or below 15.5°C. For a more complete summary and discussion of flow alternatives, please refer to the Final SEIS (Bureau of Reclamation, 2024) or see the [https://gcdamp.com/index.php/SEIS_Bypass_Releases the page for the SEIS Bypass Releases].
 [[File:SEISbypass.jpg|center|400px‎]]

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 |-
 |style="color:#000;"|
 '''2024'''

@@ Line 52: / Line 52: @@
 *Decreases threat of nonnative fish proliferation
 *Provides cold water to sustain the Lees Ferry trout fishery
 |-

@@ Line 92: / Line 92: @@
 [[Image:Trunnion.jpg|thumb|center|400px|‎Depiction of a trunnion attached to the face of Glen Canyon Dam]]
-=='''Bypass'''==
+=='''[https://gcdamp.com/index.php/SEIS_Bypass_Releases Bypass]'''==
-This is a continuation of current operations at Glen Canyon Dam (GCD) developed as part of the Smallmouth Bass Supplemental Environmental Impact Statement (SEIS). The SEIS was finalized in June of 2024 and the Record of Decision was signed and implemented in July 2024. There are 5 possible options for GCD releases to keep water temperatures at river mile 61 in Grand Canyon at or below 15.5°C. For a more complete summary and discussion of flow alternatives, please refer to the Final SEIS (Bureau of Reclamation, 2024).
+This is a continuation of current operations at Glen Canyon Dam (GCD) developed as part of the Smallmouth Bass Supplemental Environmental Impact Statement (SEIS). The SEIS was finalized in June of 2024 and the Record of Decision was signed and implemented in July 2024. There are 5 possible options for GCD releases to keep water temperatures at river mile 61 in Grand Canyon at or below 15.5°C. For a more complete summary and discussion of flow alternatives, please refer to the Final SEIS (Bureau of Reclamation, 2024) or see the [https://gcdamp.com/index.php/SEIS_Bypass_Releases the page for the SEIS Bypass Releases].
-−
-The total bypassed volume to date (July 9 - 18, 2024) is approximately 150,000 acre-feet or ~30% of the total daily release volume. Approximately 1°C of cooling is being observed at Lees Ferry (RM 0). Full effects of bypass at RM61 are still being evaluated. Water temperatures at RM 61 are estimated to remain over the 15.5°C threshold until November 1 and thus, bypass would be required for most of the summer and fall, a period of 16 weeks.
-−
-The SEIS estimated an average hydropower impact from the Cool Mix alternative of $61.73 million (226.29 GWh) over a 45-month period or $15.43 million (56.57 GWh) per year (tables 3-12 and 3-17 in Bureau of Reclamation, 2024). Bypassed water does not produce hydropower and replacement costs are estimated to be ~$1 to $2 million per week (WAPA 2024, personal communication). Observed costs are tracking estimates presented in the SEIS.
 [[File:SEISbypass.jpg|center|400px‎]]