Big Sandy Reservoir
Sweetwater County, Wyoming2,510 acresView mapDirections
Not enough samples to grade — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). No letter yet. Here is what we do have.
- Public access
- Limited data
Big Sandy Reservoir in Sweetwater County, Wyoming is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 0.7 ft visibility. Phosphorus: 45 µg/L. Surface area: 2510 acres.
- Clarity
- 0.7 ft
- Area
- 2,510 acres
- Phosphorus
- 45 µg/L
- Public access
- Yes
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Watch Big Sandy Reservoir’s letter
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Why Big Sandy Reservoir has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Big Sandy Reservoir, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded water clarity and phosphorus, but not algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by Wyoming DEQ and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
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. Grade methodology: LakeQuality methodology.
What Big Sandy Reservoir is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Big water2,510 acres
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Check local advisories before you swim.
Water quality measurements for Big Sandy Reservoir
These readings exist but are not enough for an A–F grade — see why.
Very murky, less than 0.7 ft of visibility. Phosphorus 45 µg/L. TSI 70.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.7 ft | Not graded |
| Phosphorus | 45 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 70 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Current Conditions
USGS snapshot Sep 7, 2026, 3:15 PM from gauge 09213700 (BIG SANDY RESERVOIR NEAR FARSON, WY). Station page ↗ — a live reading replaces this snapshot when the gauge responds. Missing live data is not an all-clear.
→ Big Sandy Reservoir water level: the live USGS gauge reading
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 2,510 acres |
| Public Access | Yes |
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
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. LakeQuality has not rated this lake (UNRATED) — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
What is the water quality grade for Big Sandy Reservoir?
- Big Sandy Reservoir in Sweetwater County, Wyoming is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 0.7 ft visibility. Phosphorus: 45 µg/L. Surface area: 2510 acres.
Is Big Sandy Reservoir safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
What is the water level at Big Sandy Reservoir?
- The USGS snapshot on this page for Big Sandy Reservoir is 6735.62 ft of water-surface elevation, recorded Sep 7, 2026, 3:15 PM at gauge 09213700. Current Conditions hydrates a live NWIS reading from that same station when the gauge responds. A missed live fetch is not an all-clear.
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.
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)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Named boat-access points from the USGS National Boat Ramps inventory