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Yellowtail Dam & Bighorn Lake
Billings, MontanaOctober 18, 2007
RECLAMATIONManaging Water in the West
Bighorn Lake and River Basin Investigations
• Possible Flood Storage Reallocation
• Bighorn River Basin Changes (Depletion Study)
Flood Control Storage Reallocation
BIGHORN LAKE STORAGE ALLOCATIONSDam 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
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
BIGHORN LAKE STORAGE ALLOCATIONDam 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
PROPOSED STORAGE REALLOCATIONDam 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 - Feet3645 (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
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
Bighorn Lake Average Elevation 1967-2006
3590
3600
3610
3620
3630
3640
3650
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Elev
atio
n (f
t)
Full Pool 3645
Full Pool 3640
Bighorn Lake Avg. River Release 1967-2006
0
500
1000
1500
2000
2500
3000
3500
4000
J an Feb Mar Apr May J un J ul Aug Sept Oct Nov Dec
Riv
er F
low
cfs
Full Pool 3645
Full Pool 3640
Yellowtail Power Generation GWH
010
2030
4050
6070
8090
100
J an Feb Mar Apr May J un J ul Aug Sept Oct Nov Dec
GW
H
Full Pool 3645
Full Pool 3640
Flood Control Impacts
• Not Addressed
• To Be Determined by Corps of Engineers
BIGHORN RIVER BASIN CHANGES
Bighorn Lake Average InflowPre-Drought Flows vs. Drought Flows
8 Year Average Drought Inflow53% OF 1967-1999 Period
Bighorn Lake Annual Inflow Trend
0
500000
1000000
1500000
2000000
2500000
3000000
3500000
4000000
Inflo
w a
cre-
feet
Bighorn Lake Annual Inflow Trend
0
500000
1000000
1500000
2000000
2500000
3000000
3500000
4000000
Inflo
w a
cre-
feet
Bighorn Lake Inflow Trend 1953-2007
0.0
500.0
1000.0
1500.0
2000.0
2500.0
3000.0
3500.0
4000.0
Years
Inflo
w 1
,000
af
Bighorn Lake Inflow Trend 1953-2002
0.0
500.0
1000.0
1500.0
2000.0
2500.0
3000.0
3500.0
4000.0
Year
Inflo
w 1
,000
af
Bighorn Lake Oct-Mar Gains
0
100000
200000
300000
400000
500000
600000
Gains
Bighorn Lake Oct-Mar Gains
0
100000
200000
300000
400000
500000
600000
Gains
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
QUESTIONS & COMMENTS
