Big Sandy Reservoir
Sweetwater County, Wyoming2,510 acresView mapDirections
Wyoming DEQ publishes the water-quality measurements for Big Sandy Reservoir. Here is what has been measured.
- Public access
- Limited data
Big Sandy Reservoir in Sweetwater County, Wyoming has water-quality measurements published by Wyoming DEQ, shown here as reported. Water clarity: 0.7 ft visibility. Phosphorus: 45 µg/L. Surface area: 2510 acres.
Big Sandy Reservoir is a 2,510-acre lake in Sweetwater County, Wyoming. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Wyoming DEQ, last sampled 2014-09-15. Methodology: how these readings are compared.
Big Sandy Reservoir covers about 2,500 acres in Sweetwater County. It has one public boat landing. For a place on the water, look through cabin and lake-house rentals near Big Sandy Reservoir on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Big Sandy Reservoir is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Big water2,510 acres
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Big Sandy Reservoir is safe to swim in today is a call for the Wyoming Department of Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Big Sandy Reservoir
These are the measurements Wyoming DEQ publishes for Big Sandy Reservoir, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 0.7 ft of visibility. Phosphorus 45 µg/L. TSI 70.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 0.7ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 45µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 70 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Big Sandy Reservoir
Answers come straight from the public measurements and survey records on this page.
→ Big Sandy Reservoir water level: the live USGS gauge reading
Lake Details
Surface area
2,510 acres
Public access
Yes
Listed by Wyoming DEQ
No bathymetric survey has been published for Big Sandy Reservoir, so its depth is not documented here.
Recreation & Access
- Big Sandy ReservoirPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
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Stays near Big Sandy Reservoir
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Fishing Big Sandy Reservoir
Reservoir Info (USACE NID)
Big Sandy Reservoir is a man-made reservoir impounded by the Big Sandy Dam (completed 1952), built primarily for flood risk reduction on the Big Sandy Creek; earth-type dam, 85 ft tall and 2,350 ft long.
- Surface area
- 2,510 ac
- Normal storage
- 39,700 ac-ft
- Max storage
- 54,400 ac-ft
- Drainage area
- 387.47 sq mi
- Hazard class
- High
- Owner
- BUREAU OF RECLAMATION
All listed purposes: Flood Risk Reduction;Irrigation.
Source: USACE National Inventory of Dams, NID ID WY01387 · Operator website
Nearby Lakes in Sweetwater County
Frequently asked questions about Big Sandy Reservoir
Where is Big Sandy Reservoir?
- Big Sandy Reservoir is a lake in Sweetwater County, Wyoming. Its water-quality measurements are published by Wyoming DEQ and shown on this page as reported.
What is the water quality of Big Sandy Reservoir?
- Big Sandy Reservoir in Sweetwater County, Wyoming has water-quality measurements published by Wyoming DEQ, shown here as reported. Water clarity: 0.7 ft visibility. Phosphorus: 45 µg/L. Surface area: 2510 acres.
Is Big Sandy Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Are there boat ramps on Big Sandy Reservoir?
- Big Sandy Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Big Sandy Reservoir. Public access is listed as yes.
Can I fish at Big Sandy Reservoir?
- Big Sandy Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Wyoming's fish and wildlife agency, so check its current regulations before you go.
Explore Big Sandy Reservoir across LakeQuality
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Where this data comes from
3 measurements from 1 monitoring station, 2014. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- State of Wyoming Department of Environmental Quality Watershed Program
WYDEQ_WATERSHED3 samples · 2014
Analytical methods
- Secchi
- Total Phosphorus After Block Digestion
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Named boat-access points from the USGS National Boat Ramps inventory