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Yellowtail Dam & Bighorn Lake Water Supply & Operations Meeting Billings, Montana October 8, 2009

RECLAMATION. Managing Water in the West. Yellowtail Dam & Bighorn Lake Water Supply & Operations Meeting Billings, Montana October 8, 2009. Welcome & Introductions. Purpose of Meeting. Public outreach / education regarding Yellowtail Dam & Bighorn Lake

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Yellowtail Dam & Bighorn Lake Water Supply & Operations Meeting Billings, Montana October 8, 2009

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  1. RECLAMATION Managing Water in the West Yellowtail Dam & Bighorn Lake Water Supply & Operations Meeting Billings, Montana October 8, 2009

  2. Welcome & Introductions

  3. Purpose of Meeting • Public outreach / education regarding Yellowtail Dam & Bighorn Lake • Recap operations during water year 2009 • Present operation scenarios for fall / winter 2009-2010 • Obtain feedback / comment from public & interested parties

  4. Montana Area Office is responsible for managing the water supplies and administering Reclamation programs for Reclamation projects located in Montana east of the continental divide.

  5. The Montana Area Office monitors hydrologic and climatic conditions, prepares inflow projections and operation plans, and directs water releases from Yellowtail Dam.

  6. YELLOWTAIL DAM, BIGHORN LAKE AND AFTERBAY

  7. YELLOWTAIL DAM and BIGHORN LAKE Spillway Inlet Bighorn Lake Visitor Center Powerplant

  8. YELLOWTAIL DAM, BIGHORN LAKE and AFTERBAY Yellowtail Afterbay Dam Substation Visitor Center Yellowtail Dam

  9. YELLOWTAIL AFTERBAY DAM and AFTERBAY Sewage Lagoons Afterbay Sluice Gates Afterbay Dam Bighorn Canal Radial Gates

  10. BIGHORN LAKE STORAGE ALLOCATIONS Dam Crest Maximum Water Surface or Top of Surcharge Elev. 3660.00 (1,381,189 Acre-Feet) Elev. 3660.0 SURCHARGE - 52,829 Acre-Feet Top of Exclusive Flood Elev. 3657.00 (1,328,360 AF) EXCLUSIVE FLOOD CONTROL - 258,331 Acre-Feet Top of Joint Use Elev. 3640.00 (1,070,029 Acre-Feet) JOINT USE - 240,342 Acre-Feet Top of Active Conservation Elev. 3614.00 (829,687 Acre-Feet) Spillway crest Elev. 3593.00 ACTIVE CONSERVATION - 336,103 Acre-Feet FISH WILDLIFE RECREATION AGRICULTURE POWER MUNICIPAL INDUSTRIAL Top of Inactive Elev. 3547.00 (493,584 Acre-Feet) Powerplant Penstock Elev. 3450.00 INACTIVE CONSERVATION - 477,576 Acre-Feet Irrigation Outlet Elev. 3400.00 River Outlet Elev. 3300.0 Top of Dead Elev. 3296.50 (16,008 Acre-Feet) DEAD - 16,008 Acre-Feet Streambed Elev. 3166.0

  11. OPERATIONS - A BALANCING ACT AMONG THE COMPETING INTERESTS

  12. Recap of Water Year 2009 • Mountain Snowpack • Precipitation • Inflow to Bighorn Lake • Bighorn River Releases • Bighorn Lake Storage Conditions

  13. Recap of Water Year 2009

  14. Recap of Water Year 2009

  15. Peaked on 4/16 @ 106% of average Recap of Water Year 2009

  16. Recap of Water Year 2009

  17. Bighorn Lake Annual Inflow Distribution Based on 1967-2009 Data

  18. Recap of Water Year 2009 2009 – 2,730 kaf Ave. – 2,357 kaf

  19. Recap of Water Year 2009 2009 – 1,657 kaf Ave. – 1,113 kaf

  20. Recap of Water Year 2009 WY-2009 April-July Inflow – 1,657 kaf (149% of average) WY-2009 Annual Inflow – 2,730 kaf (116% of average)

  21. Recap of Water Year 2009

  22. Recap of Water Year 2009 Peaked on 7/06 at 3647.92 feet 7.92 feet above full pool 5.42 feet higher than in 2008

  23. Summary Recapping Water Year 2009 • Water year started out with good precipitation – Oct. above average but dropped to below average during Nov. • Precipitation returned to above average during Dec. & Jan. Precipitation dropped to well below average in Feb. returned to well above average during March & April. Unlike last year, precipitation was well below average in May but returned to well above average in June through Aug. with Sept. dropping well below normal. • October-March inflows were 80% of average totaling 732 kaf. April-July inflows were 149% of average totaling 1,657 kaf. • Annual inflows were 116% of average totaling 2,730 kaf. • Bighorn Lake reached a low level at elevation 3619.50 on May 20. • Bighorn Lake reached a peak level at elevation 3647.92 on July 6. • Bighorn Lake rose 28.4 feet from May 20 to July 6. • Fall & winter releases were maintained at 2,450 cfs. • Beginning in early April, releases were gradually increased from 2,450 cfs to nearly 4,440 cfs by late May. • Beginning in late June & into early July, releases were gradually increased to a peak of 12,500 cfs to control the spring runoff and rate of fill. • Rains in June accompanied by unusually large releases out of Buffalo Bill & Boysen, caused inflows to reach a peak of 16,760 cfs on June 22. • Since July 6, storage has slowly declined to elevation 3640 by September 22 and has essentially remained near full. • Current lake level is only about 0.5 foot below full, 2nd highest of record and releases are currently being maintained at 2,800 cfs.

  24. BIGHORN LAKE CURRENT CONDITIONS October 7, 2009 Elevation 3639.48 ft – 0.52 feet below full pool 0.13 feet lower than last year Storage 1,063,500 af – 99% full Inflows = 3,450 cfs Total Outflow = 2,800 cfs River = 2,800 cfs BIA Canal = 0 cfs

  25. Inflow Forecast to Bighorn Lake – WY-2010 WY-2009 Oct-Mar Actual Inflow – 732 kaf WY-2010 Oct-Mar Inflow Forecast – 778 kaf

  26. OPERATION SCENARIOS

  27. Bighorn Lake Operation Scenarios Most Probable Inflow Scenario: • October – March Inflow forecast at 778 kaf • Maintain fall and winter release at 2,720 cfs through March • Reservoir level expected to reach elevation 3620.6 by the end of March. • Generation during October – March would total 382.6 GWHrs.

  28. Most Probable Inflow Scenario

  29. Most Probable Inflow Scenario

  30. Bighorn Lake Operation Scenarios Minimum Probable Inflow Scenario: • October – March Inflow forecast at 685 kaf • Maintain fall and winter release at 2,700 cfs through January and gradually reduce to 2,300 cfs in February and to 2,000 cfs in March • Reservoir level expected to reach elevation 3618.4 by the end of March. • Generation during October – March would total 349.9 GWHrs.

  31. Minimum Probable Inflow Scenario

  32. Minimum Probable Inflow Scenario

  33. Bighorn Lake Operation Scenarios Maximum Probable Inflow Scenario: • October – March Inflow forecast at 843 kaf • Maintain fall and winter release at 2,770 cfs through February and increase release to 3,535 cfs during March • Reservoir level expected to reach elevation 3620.8 by the end of March • Generation during October – March would total 408.9 GWHrs.

  34. Maximum Probable Inflow Scenario

  35. Maximum Probable Inflow Scenario

  36. Three Probable Runoff Scenarios

  37. Three Probable Runoff Scenarios

  38. Discussion & Comments

  39. Comments ? The information presented at this meeting can be found on the Montana Area Office website at:www.usbr.gov/gp/mtao/yellowtail/index.cfm. Please mail comments to: Ms. Paula A. Holwegner Bureau of Reclamation 2900 4th Avenue North, Suite 501 Billings, MT 59107 fax your comments to: 406-247-7338 or email your comments to: pholwegner@gp.usbr.gov by October 13, 2009

  40. Reclamation’s Internet Website http://www.usbr.gov/gp/water/ • near real-time data available through the HYDROMET data system • summaries and plots of historical data • annual reservoir operating plan publication • monthly water supply reports • project data • snow plots • links to related internet sites

  41. Bighorn Lake April-July InflowForecasted vs Actual

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