1. Yellowtail Dam & Bighorn Lake Billings, Montana October 18, 2007 RECLAMATION Managing Water in the West

2. Bighorn Lake and River Basin Investigations Possible Flood Storage Reallocation Bighorn River Basin Changes (Depletion Study)

3. Flood Control Storage Reallocation

4. BIGHORN LAKE STORAGE ALLOCATIONS Dam Crest Elev. 3660.0 Top of Conservation Elev. 3547.00 (493,584 Acre - Feet) Surcharge (52,829 af) 3657 (1,328,360 AF) Exclusive Flood Control - 258,331 Acre - Feet 3640 (1,070,029 Acre - Feet) Joint Use - 240,342 Acre - Feet 3614 (829,687 Acre - Feet) Top of Dead Elev. 3296.50 (16,008 Acre - Feet) Active Conservation - 336,103 Acre - Feet Inactive Conservation - 477,576 Acre - Feet Dead - 16,008 Acre - Feet

7. Scenarios Modeled & Reviewed Normal Full Pool Elev. 3640, Current Flood Control Storage Allocation Normal Full Pool Elev 3645, Modified Flood Control Storage Allocation with top of Joint Use raised 5 ft

8. BIGHORN LAKE STORAGE ALLOCATION Dam Crest Elev. 3660.0 Top of Conservation Elev. 3547.00 (493,584 Acre - Feet) Surcharge (52,829 af) 3657 (1,328,360 AF) Exclusive Flood Control - 258,331 Acre - Feet 3640 (1,070,029 Acre - Feet) Joint Use - 240,342 Acre - Feet 3614 (829,687 Acre - Feet) Top of Dead Elev. 3296.50 (16,008 Acre - Feet) Active Conservation - 336,103 Acre - Feet Inactive Conservation - 477,576 Acre - Feet Dead - 16,008 Acre - Feet

9. PROPOSED STORAGE REALLOCATION Dam Crest Elev. 3660.0 Top of Inactive Conservation Elev. 3547.00 (493,584 Acre - Feet) Surcharge 3657 (1,328,360 AF Exclusive Flood Control - 190,846 Acre - Feet 3645 (1,1370,514 Acre - Feet) Joint Use - 307,827 Acre - Feet 3614 (829,687 Acre - Feet) Top of Dead Elev. 3296.50 (16,008 Acre - Feet) Active Conservation - 336,103 Acre - Feet Inactive Conservation - 477,576 Acre - Feet Dead - 16,008 Acre - Feet

10. Possible Flood Storage Reallocation Current Joint Use Pool –240,342 –Elevation 3614-3640 Exclusive Flood Pool –258,331 acre-feet –Elevation 3640-3657 Conservation Pool –567,445 acre-feet –Elevation 3547-3640 Reallocation Joint Use Pool –307,827 acre-feet –Elevation 3614-3645 Exclusive Flood Pool –190,846 acre-feet –Elevation 3645-3657 Conservation Pool –643,930 acre-feet –Elevation 3547-3645 Total Flood Control Storage Space 498,673 acre-feet Elev. 3614-3657

14. Flood Control Impacts Not Addressed To Be Determined by Corps of Engineers

15. BIGHORN RIVER BASIN CHANGES

16. Bighorn Lake Average Inflow Pre-Drought Flows vs. Drought Flows

17. 8 Year Average Drought Inflow 53% OF 1967-1999 Period

24. Bighorn River Investigations Bighorn Lake Flood Pool Reallocation –Raise Joint Use Pool 5 feet Bighorn River Basin Depletion Study –New Irrigation or other Development –New Reservoir Storage –New well Development –Changes in Land Management Practices –Changes in Forest Management

25. QUESTIONS & COMMENTS