Wyoming State Water Plan, Wyoming Water Development Office
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Powder/Tongue River Basin Water Plan
Technical Memoranda

SUBJECT: Appendix J
Storage Operation and Description
SAWMILL

PREPARED BY: HKM Engineering Inc.

DATE: March 2002


KEY STORAGE FACILITIES

Reservoir: SAWMILL
Date: 28 Feb. 2001
Location: SENE 26,T54N,R87W
Owner: SAWMILL RESERVOIR COMPANY (DON ROBERTS)
Year of Construction: 1960
Enlargement History: 1972 . enlargement
1991 . resurvey and filing on unpermitted water
Total Storage: 1831 acre-feet
Active Storage: 1275 acre-feet
Dead Storage: 61.91 acre-feet
Area/Capacity Data: (Source: 1994 table on file with State Engineer's Office, Water Div. II)

Elevation Area Acre-Ft.
Increment
Acre-Ft.
Released
Acre-Ft.
Remaining
Ft. Below
Spillway
95 78.65
0.00 1275.00 0


73.00


94 75.28
73.00 1202.00 1


73.00


93 71.91
146.00 1129.00 2


73.00


92 68.54
219.00 1056.00 3


24.09


91.67 67.45
243.09 1031.91 3.33


43.37


91 65.20
286.46 988.54 4


64.73


90 61.83
351.19 923.81 5


58.13


89 60.35
409.32 865.68 6


58.13


88 58.87
467.45 807.55 7


58.13


87 57.40
525.59 749.41 8


58.13


86 55.92
583.72 691.28 9


58.13


85 54.44
641.85 633.15 10


49.41


84 52.43
691.26 583.74 11


49.41


83 50.42
740.67 534.33 12


49.41


82 48.40
790.09 484.91 13


49.41


81 46.40
839.50 435.50 14


49.41


80 44.39
888.91 386.09 15


39.17


79 42.30
928.08 346.92 16


39.17


78 40.21
967.25 307.75 17


39.17


77 38.13
1006.41 268.59 18


39.17


76 36.04
1045.58 229.42 19


39.17


75 33.95
1084.75 190.25 20


25.67


74 30.64
1110.42 164.58 21


25.67


73 27.32
1136.09 138.91 22


25.67


72 24.01
1161.75 113.25 23


25.67


71 20.69
1187.42 87.58 24


25.67


70 17.38
1213.09 61.91 25


13.72


69 15.13
1226.81 48.19 26


13.72


68 12.88
1240.53 34.47 27


13.72


67 10.63
1254.25 20.75 28


3.58


66.74 10.06
1257.83 17.17 28.26


5.99


66 8.40
1263.82 11.18 29


8.10


65 6.15
1271.92 3.08 30


3.08


64 0.00
1275.00 0.00 31
Dam Construction Type: Earth Fill
Outlet: Single 24-inch diam. welded steel pipe
Spillway: 5.25' x 20' spillway cut into granite bedrock with a capacity of 1600 cfs.
End-of-Month Storage Records: No
Water Rights: Source: Tabulation of Adjudicated Surface Water Rights of the State of Wyoming, Water Division Number Two, Oct. 1999.)

Reservoir Permit Number Permitted Use Priority Date Volume (af) Headgate Location (S-T-R)
Sawmill Res 6890R I 11-10-1960 970 26-54-087
Enl. Sawmill Res. 7268R I 07-30-1969 287.83 26-54-087
Designated Use:Irrigation
Recreational Use:Fishing
Associated Irrigation Diversions:(Source: Bill Knapp, Div. II water commissioner/hydrographer)

Diversion Tributary
P.K. Ditch Big Goose
Alliance Ditch Big Goose

Note: All of the water in Sawmill is unattached, meaning it could be delivered to any Big Goose Creek diversion, depending on the owner or lease situation.
Associated Industrial Diversions:None
Operational Discussion: Sawmill Reservoir begins releases with the following timing:

First release timing, Sawmill Reservoir

Wet Year Average Year Dry Year
2nd week of August 4th week of July 2nd week of July

According to water commissioners, the Sawmill Reservoir outlet works is typically opened to flow 15 cfs, but as the head on the upstream side of the dam falls, the flow falls with it to approximately 5 cfs over the course of the season.

The operator typically ends releases for the season on Oct. 1.

Though in past years, the owner has been able to irrigate from storage in Dome and Park reservoirs, much of Park Reservoir's shares have changed ownership, necessitating that the owner of Sawmill use more of Sawmill's capacity.
References: Bill Knapp, State Engineer's Office Water Div. 2 water commissioner, interview, 20 Feb. 2001.

Active Dams, State Engineer's Office Safety of Dams Engineering Div. Database, transmitted by Larry Stockdale, Safety of Dams engineering consultant, 16 Feb. 2001.

Tabulation of Adjudicated Surface Water Rights of the State of Wyoming, Water Division Number Two, Oct. 1999, database transmitted by Rebecca Mathisen, SEO Technical Services Division administrator, 8 Sept. 2000.

Net Evaporative Loss from Sawmill Reservoir:

Lewis Annual Evaporation (in.)45
Total Storage (acre-feet)1,831


Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Average percent of total storage 56.72 57.55 57.87 60.80 71.16 72.71 68.17 64.03 57.62 57.03 58.79 60.84
Generated storage (acre-feet) 1039 1054 1060 1113 1303 1331 1248 1172 1055 1044 1077 1114
Corresponding area (acres) 67.45 67.45 68.54 68.54 78.65 78.65 75.28 71.91 67.45 67.45 68.54 68.54

Calculations:
Monthly Lewis Evap. (inches) 1.215 1.125 1.755 3.6 5.175 5.895 7.695 7.02 5.175 3.42 1.755 1.17
Monthly Precipitation (inches) 1.75 1.75 2.25 2.75 3.25 2.75 1.75 1.25 2.25 1.75 1.75 1.75
Net Evaporation (inches) 0 0 0 0.85 1.925 3.145 5.945 5.77 2.925 1.67 0.005 0 TOTAL
Total Net Evaporation (acre-feet) 0 0 0 5 13 21 37 35 16 9 0 0 136