Hydrology

Upper Colorado River Basin Hydrology Upper Colorado River Basin regularly experiences significant year to year hydrologic variability. During the 21-year period 2000 to 2020, however, the unregulated inflow to Lake Powell, which is a good measure of hydrologic conditions in the Colorado River Basin, was above average in only 4 out of the past 19 years. The period 2000-2020 is the lowest 21-year period since the closure of Glen Canyon Dam in 1963, with an average unregulated inflow of 8.62 maf, or 80 percent of the 30-year average (1981-2010). (For comparison, the 1981-2010 total water year average is 10.83 maf.) The unregulated inflow during the 2000-2020 period has ranged from a low of 2.64 maf (24 percent of average) in water year 2002 to a high of 15.97 maf (147 percent of average) in water year 2011. In water year 2018 unregulated inflow volume to Lake Powell was 4.6 maf (43 percent of average), the third driest year on record above 2002 and 1977. [1]

Current Status	Current Operations	Inflow Forecasts and Model Projections

Updates Upper Colorado Region Homepage Hydrodata dashboard for Lake Powell Lake Powell Snow Chart Lake Powell Inflow Forecast Lake Powell Elevation Projections Lake Powell Release Projections Glen Canyon Dam Operations USBR Weekly Water Reports Upper Colorado Region Weekly Hydrology Summary Reservoir inflows (forecast and observed) Reservoir releases SNOTEL Lower Colorado Water Supply Report Water use Lower Colorado River Water Accounting Colorado River Basin Tea-Cup Diagrams USBR Monthly/Annual Reports 24-Month Studies Most Probable 24-Month Study Probable Minimum 24-Month Study Probable Maximum 24-Month Study Monthly Summaries Annual Operating Plans for Colorado River reservoirs Snow Pack Reports Upper Colorado River Basin Snow Water Tracking Upper Colorado Basin Conditions Map Bureau of Reclamation- Snow Pack Report SNOWTEL Report The snowtel report is a calculating report, and takes approximately 3 minutes to run. Select the report under "Public", listed as "Colorado River above Lake Powell" (116 snowtel sites). Data source is updated at least daily. U.S. Drought Monitor U.S. Drought Monitor Tree Flow Data Inflow Volumes to Lake Powell and Release Volumes from Glen Canyon Dam 10-year average natural inflow (2016-2025): -- maf 10-year average unregulated inflow (2016-2025): 8.06 maf 10-year average release (2016-2025): 8.30 maf 10-year average Lees Ferry Gage (2016-2025): 8.44 maf Water Year Naturalized Flow at Lees Ferry (maf) Unregulated Inflow (maf) Release Volume (maf) Lees Ferry Gage (maf) 2026 -- ~3.879 ~6.000 -- 2025 08.50 04.688 07.481 07.503 2024 11.875 07.981 07.480 07.551 2023 17.41 13.421 08.580 08.749 2022 09.85 06.084 07.000 07.083 2021 07.15 03.502 08.230 08.293 2020 09.89 05.847 08.230 08.436 2019 17.67 12.951 09.001 09.264 2018 8.63 04.612 09.000 09.171 2017 16.40 11.905 09.000 09.170 2016 13.44 09.616 09.000 09.138 2015 13.41 10.174 09.000 09.157 2014 13.98 10.381 07.480 07.590 2013 09.11 05.117 08.232 08.289 2012 08.50 04.908 09.466 09.542 2011 20.16 15.971 12.518 12.753 2010 12.32 08.426 08.235 08.437 2009 14.27 10.220 08.236 08.406 2008 16.21 12.086 08.978 09.180 2007 12.56 08.754 08.231 08.421 2006 12.61 08.626 08.228 08.507 2005 16.89 12.795 08.232 08.395 2004 09.59 05.913 08.231 08.348 2003 10.53 06.161 08.229 08.372 2002 05.93 02.643 08.230 08.347 2001 11.04 06.994 08.236 08.361 2000 10.56 06.936 09.381 09.529 1999 16.43 12.800 11.204 11.430 1998 16.97 13.520 13.510 13.440 1997 21.15 17.053 13.824 13.874 1996 14.07 10.402 11.522 11.532 1995 19.80 15.905 09.223 09.242 1994 10.64 06.794 08.289 08.304 1993 18.63 14.437 08.102 08.137 1992 11.10 07.352 08.002 08.023 1991 12.35 08.801 08.121 08.131 1990 09.00 05.311 08.140 08.151 1989 09.60 05.939 07.981 07.994 1988 11.68 07.989 08.144 08.160 1987 16.61 13.377 13.429 13.450 1986 22.36 18.546 16.848 16.866 1985 21.06 17.517 19.094 19.109 1984 24.18 20.846 20.499 20.518 1983 23.70 20.371 17.493 17.520 1982 16.67 12.771 08.304 08.323 1981 08.68 05.639 08.295 08.316 1980 17.27 13.682 10.907 10.950 1979 17.55 14.189 08.297 08.333 1978 14.85 11.059 08.354 08.369 1977 05.52 03.529 08.260 08.269 1976 11.21 08.431 08.482 08.494 1975 16.53 13.095 09.255 09.274 1974 12.96 09.970 08.266 08.277 1973 19.14 15.974 10.108 10.141 1972 12.44 09.329 09.311 09.330 1971 14.73 11.798 08.591 08.607 1970 15.06 11.992 08.692 08.688 1969 14.45 11.520 08.823 08.850 1968 13.34 10.319 08.334 08.358 1967 11.71 08.979 07.797 07.824 1966 11.06 08.689 07.854 07.870 1965 18.36 15.046 10.820 10.835 1964 10.38 07.492 02.413 02.427 https://usea.org/sites/default/files/event-/Final_Colorado_Overview.pdf http://www.lakepowell.org/page_two/what_s_new/what_s_new.html https://www.hcn.org/blogs/goat/is-lake-powell-really-shrinking

Stream Flow Gages Lake Powell Water Level Graphs Glen Canyon Dam releases (SCADA) Glen Canyon Dam releases (HDB), SDI for total release = 1872 Water Holes Canyon above the mouth Colorado River at Lees Ferry Paria River near Kanab, UT Paria River at Lees Ferry, AZ Badger Creek below highway 89A near Vermillion Cliffs, AZ Tanner Wash below highway 89A near Bitter Springs, AZ House Rock Wash above Emmett Wash near Cliff Dwellers, AZ North Canyon near Cliff Dwellers, AZ Shinumo Wash in Twentynine Mile Canyon near Cedar Ridge, AZ Colorado River near river mile 30 Colorado River above Little Colorado River near Desert View, AZ Moenkopi Wash at Moenkopi, AZ Moenkopi Wash near Cameron, AZ Little Colorado River at Grand Falls, AZ Little Colorado River near Cameron, AZ Little Colorado River above the mouth near Desert View, AZ Colorado River near Grand Canyon, AZ Bright Angel Creek near Grand Canyon, AZ Shinumo Creek Kanab Creek above the mouth near Supai, AZ Havasu Creek above the mouth near Supai, AZ Colorado River above National Canyon near Supai, AZ Colorado River above Diamond Creek near Peach Springs, AZ Lake Mead Water Level Graphs Projects Presentations and Papers 2026 Basin Hydrology and Operations 2025 Basin Hydrology and Operations Basin Hydrology and Operations Colorado River Basin Reservoir Storage: where do we stand? 2024 Basin Hydrology and Operations Basin Hydrology and Operations Basin Hydrology and Operations Basin Hydrology and Operations Upper Colorado River Basin IRA Drought Mitigation Programs Basin Hydrology and Operations Reservoir Storage at the End of 2023 – Holding On to What We Have 2023 Basin Hydrology, Operations and Water Quality Basin Hydrology and Operations Basin Hydrology, Operations, and Water Quality Basin Hydrology and Operations Glen Canyon Dam Operations and Upper Basin Hydrology and Water Quality Basin Hydrology and Water Quality 2022 Evaluating the Accuracy of Reclamation’s 24-Month Study Lake Powell Projections Basin Hydrology, Operations and Water Quality AMP Role Relative to Implementing the Drought Response Operating Agreement Basin Hydrology, Operations and Water Quality Basin Hydrology, Operations and Water Quality Basin Hydrology and Operations Basin Hydrology, Operations, and Water Quality Basin Hydrology, Operations and Water Quality Basin Hydrology, Water Quality, and Operations 2021 Colorado River Basin August 2021 5-year Projected Future Conditions Long-Term Hydrologic Projections for the Colorado River Basin and Methods for Considering Uncertainty Colorado River Basin April 2021 5-year Projected Future Conditions Basin Hydrology and Operations Basin Hydrology and Operations Update on Hydrology, Operations and Water Quality Conditions Basin Hydrology and Operations Basin Hydrology and Operations 2020 TWG Basin Hydrology and Operations Basin Hydrology, Reservoir Operations 2020 and 2021 Hydrograph Hydrology, Operations and Reservoir Release presentation Hydrology, Operations and Reservoir Release presentation Hydrology, Operations and Reservoir Release 2019 Basin Hydrology, Reservoir Operations and 2020 Hydrograph Presentation 2018 Urban Waterfronts 2018 Basin Hydrology, Water Years 2018-2019 Operations PPT Basin Hydrology, Reservoir Operations 2018 and 2019 Hydrograph How Will the Colorado Run? The Colorado River in a Warmer World Basin Hydrology, Water Years 2018-2019 Operations PPT Basin Hydrology, Reservoir Operations 2018 and 2019 Hydrograph PPT The 21st Century Colorado River Hot Drought and Implications for the Future PPT Basin Hydrology, Water Years 2018-2019 Operations PPT Basin Hydrology, Water Years 2018-2019 Operations PPT Basin Hydrology, Operations and 2018 Hydrograph PPT Basin Hydrology, Water Years 2018-2019 Operations PPT 2017 Analysis of Water Losses and Impacts to the Grand Canyon Ecosystem of the "Fill Mead First" Proposal Fill Mead First: A technical assessment (Summary) Fill Mead First: A technical assessment (Analysis) Basin Hydrology and Operations February 2017 Glen Canyon Montly Operational Coordination Call Basin Hydrology, and 2017-2018 Operations Analysis of Water Losses and Impacts to the Grand Canyon Ecosystem of the "Fill Mead First" Proposal and PPT Basin Hydrology, Operations and 2018 Hydrograph 2016 August 2016 DOI-DOE Federal Family call on Glen Canyon Operations Fill Mead First – A Technical Assessment Basin Hydrology and Water Year (WY) 2017 Hydrograph Basin Hydrology, Operations, and 2017 Hydrograph TWG: Basin Hydrology, Operations, and 2017 Hydrograph Basin Hydrology, Operations, and 2017 Hydrograph Glen Canyon Dam Operations During Equalization Project 2: Streamflow, Water Quality, Sediment Transport, and Sand Budgets in the Colorado River Ecosystem 2015 2016 Annual Operating Plan California Drought Monitor Lake Mead Issues and Lower Basin Shortage Preparedness Lake Mead Issues and Lower Basin Shortage Preparedness - Presentation Basin Hydrology Operations, and 2016 Hydrograph Basin Hydrology Operations, and 2016 Hydrograph 2016 Annual Operating Plan Basin Hydrology and WY 2016 Hydrograph Hydrology Update and 2016 Hydrograph Water Quality in Lake Mead and Upstream Influences: Dissolved Oxygen during 2014 Basin Hydrology, Operations, and 2016 Hydrograph Panel on Current Projects and Issues in Utah Central Utah Project Meeting the Mitigation Requirement for the Bonneville Unit CUP Current Projects and Issues in Utah Provo Area Office 2014 Colorado River Annual Operating Plan and Drought Contingency Planning DOI-DOE Hydrograph Development for Water Year 2015 Basin Hydrology, Operations Basin Hydrology, Operations, and 2015 Hydrograph Basin Hydrology, Operations, and 2015 Hydrograph and AIF: Development of Water Year 2015 Hydrograph Basin Hydrology, Operations, and 2015 Hydrograph Panel on the Potential Effects of Long-Term Drought on Colorado River Operations Near Term Risks: Options to Address Declining Reservoirs State of Nevada Concerns 2013 Water Year 2014 Hydrograph Basin Hydrology and Operations Colorado River Basin Hydrology and Projected Glen Canyon Dam Operations DOI/DOE FY14 Hydrograph Approved FY14 Hydrograph Glen Canyon Dam Facility Management Basin Hydrology and Operations Colorado River Basin Water Supply and Demand Study Executive Summary--Pre-Production Copy of the Colorado River Basin Water Supply and Demand Study Colorado River Basin Water Study & Demand Study - Final Study Reports 2012 Basin Hydrology Water Year 2013 Hydrograph TWG Report: 2013 Hydrograph DOI and DOE Operating Hydrograph Recommendations for GCD (2012 water year) Water Year 2013 Hydrograph TWG Motion 2013 Hydrograph Development FY2013 Hydrograph (from 8/2011 AMWG meeting) Basin Hydrology and Operations Flow Temp Turbidity 2011 2012 Hydrograph Basin Hydrology 2012 Hydrograph Development Department of the Interior and Department of Energy Operating Hydrograph Recommendations for Glen Canyon Dam (2012 Water Year), June 6, 2011 Basin Hydrology Secure Water Act Section 9503 (c) - Water and Climate Change WY2012 Hydrograph Development 2012 Hydrograph Development Grand Canyon Trust Proposed FY2012 Hydrograph Bureau of Reclamation Updates 2010 Fiscal Year 2011-12 Hydrograph and E-mail Message to the AMWG from Anne Castle Dated July 23, 2010, Subject: July 23 Final Draft DOI-DOE Proposed Hydrograph Recommendations Department of the Interior and Department of the Energy Recommendations for Glen Canyon Dam with August 23, 2010, edits Grand Canyon Protection Act Report on Modeling the 2008-2010 Period to Support Development of the 2011 Hydrograph Proposed Water year 2011 Hydrograph: Impacts on CRSP Electric Power Resources Grand Canyon Trust Hydrograph Proposal Basin Hydrology and Operations Basin Hydrology and PPT Figure 1, AOP, BOR, AMWG monthly volumes 2009 FY2010-11 Draft Budget, Workplan, and Hydrograph Basin Hydrology PPT Basin Hydrology and PPT ***DRAFT*** Evidence for the Failure of the Modified Low Fluctuating Flow Alternative (MLFFA) to Benefit Most Ecological Resources in Grand Canyon Hazel et al. 2006. Stage-Discharge Relations for the Colorado River in Glen, Marble, and Grand Canyons, Arizona: U.S. Geological Survey Open-File Report 2006-1243, 7 p Topping et al. 2003. Computation and analysis of the instantaneous-discharge record for the Colorado River at Lees Ferry, Arizona, May 8, 1921 through September 30, 2000: U.S. Geological Survey Professional Paper 1677, 118 p. Other Stuff