USGS Water-Year Summary for Site 09213700

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	Available Parameters
	00054 Reservoir storage(Obs.)
	62614 Elevation, lake/res, NGVD29(Obs.)

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Water year 2024: 2023-10-01 to 2024-09-30

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USGS Water-Year Summary 2024

09213700 BIG SANDY RESERVOIR NEAR FARSON, WY

LOCATION - Lat 42°14'57", long 109°25'43" referenced to North American Datum of 1927, in NE 1/4 NW 1/4 NW 1/4 sec.11, T.26 N., R.106 W., Sweetwater County, WY, Hydrologic Unit 14040104, 20.5 mi upstream from Little Sandy Creek, and 10.1 mi north of Farson.

DRAINAGE AREA - 386 mi².

REVISIONS HISTORY - WDR WY-98-1: 1996, 1997.

SURFACE-WATER RECORDS

PERIOD OF RECORD - May 1987 to current year.

GAGE - Water-stage recorder. Elevation of gage is 6,770.00 ft above NGVD of 1929, levels by U.S. Bureau of Reclamation and 6,774.89 ft above NAVD of 1988, by USGS GNSS survey. U.S. Geological Survey data collection platform with satellite telemetry at station.

REMARKS -

The reservoir is formed by an earth fill dam, with lowest elevation of the reservoir at 6,700.0
ft (NGVD29), storage began in April 1953. Total capacity, 64,692 acre-ft at elevation 6,767.5 ft (NGVD29), not
including 1,400 acre-ft of dead storage in a permanent pool at elevation 6,720.0 ft (NGVD29), trash rack sill. Concrete spillway
begins to release water when lake elevation reaches 6,762.5 ft (NGVD29). Spillway elevation was increased 5 feet during 2023
per US Bureau of Reclamation (USBR).  Old spillway elevation was 6,757.7 ft (NGVD29) as modified in 2017 from previously reported elevations. 
Reservoir is used for storage of irrigation water and for recreation.

A capacity table (elevations, in feet, and contents, in acre-feet) follows:

Reservoir Elevation-Capacity Table

Elevation, in ft (NGVD29)	Elevation, in ft (NAVD88)	Capacity, in acre-ft	Elevation, in ft (NGVD29)	Elevation, in ft (NAVD88)	Capacity, in acre-ft
6,720.0	6,724.9	0	6,750.0	6,754.9	22,175
6,730.0	6,734.9	2,695	6,760.0	6,764.9	42,901
6,740.0	6,744.9	8,647	6,767.5	6,772.4	64,692

For NAVD88 elevations add 4.897ft to NGVD29.

Point	Elev NGVD29	Elev NAVD88	Comments
Dam shelter ground	6770.000	6774.897
Concrete spillway	6762.500	6767.397	After 2023 increase of 5 ft
Trash rack sill	6720.000	6724.897	Permanent pool elev (0 ac-ft active storage, 1,400 ac-ft dead storage)
Bottom reservoir	6700.000	6704.897

EXTREMES FOR PERIOD OF RECORD - Maximum contents, 51,860 acre-ft, June 10, 2024, at elevation 6,763.29 ft (NGVD29). Minimum contents, 12.6 acre-ft estimated, August 18, 2021, elevation 6,720.00 ft (NGVD29), from manual measurement during spillway repair operations.