Big Sand Wash Reservoir
Duchesne County, UtahView mapDirections
Utah DWQ publishes the water-quality measurements for Big Sand Wash Reservoir. Here is what has been measured.
- Mesotrophic
- 22 ft max depth
- Limited data
Big Sand Wash Reservoir in Duchesne County, Utah has water-quality measurements published by Utah DWQ, shown here as reported. Water clarity: 10.7 ft visibility. Phosphorus: 11.7 µg/L. Chlorophyll-a (algae): 2.3 µg/L.
Big Sand Wash Reservoir is a mesotrophic lake in Duchesne County, Utah with an estimated average depth of about 22 feet. Public access is available with 1 public boat landing. Compared to the 8 other monitored lakes in Duchesne County, Big Sand Wash Reservoir ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Utah DWQ, last sampled 2023-08-22. Methodology: how these readings are compared.
What Big Sand Wash Reservoir is good for
From access and monitoring records, not editorial picks.
- Clear water10.7 ft of visibility
- Boat launch1 documented ramp
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Big Sand Wash Reservoir is safe to swim in today is a call for the Utah Division of Water Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Big Sand Wash Reservoir
These are the measurements Utah DWQ publishes for Big Sand Wash Reservoir, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 10.7 ft. Phosphorus 11.7 µg/L. Chlorophyll-a 2.3 µg/L. TSI 41.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 10.7ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 11.7µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 2.3µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 41 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Big Sand Wash Reservoir
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~22 ft est.
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Utah has not published bathymetry for Big Sand Wash Reservoir.
Lake Size & Watershed
Watershed (drainage) area
23 sq mi
HydroLAKES / HydroSHEDS
Surface area
329 acres
HydroLAKES / HydroSHEDS
Shoreline
4.9 mi
HydroLAKES / HydroSHEDS
Elevation
5,889 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Big Sand State ParkSemi-private
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
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Fishing Big Sand Wash Reservoir
Reservoir Info (USACE NID)
Big Sand Wash Reservoir is a man-made reservoir impounded by the Big Sand Wash West (completed 2006), built primarily for irrigation on the Big Sand Wash; earth-type dam, 55 ft tall and 2,950 ft long.
- Normal storage
- 18,800 ac-ft
- Max storage
- 19,600 ac-ft
- Drainage area
- 26.64 sq mi
- Hazard class
- High
- Owner
- MOON LAKE WATER USERS
Source: USACE National Inventory of Dams, NID ID UT53328 · Operator website
Nearby Lakes in Duchesne County
Frequently asked questions about Big Sand Wash Reservoir
Where is Big Sand Wash Reservoir?
- Big Sand Wash Reservoir is a lake in Duchesne County, Utah. Its water-quality measurements are published by Utah DWQ and shown on this page as reported.
What is the water quality of Big Sand Wash Reservoir?
- Big Sand Wash Reservoir in Duchesne County, Utah has water-quality measurements published by Utah DWQ, shown here as reported. Water clarity: 10.7 ft visibility. Phosphorus: 11.7 µg/L. Chlorophyll-a (algae): 2.3 µg/L.
Is Big Sand Wash Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Big Sand Wash Reservoir?
- No published bathymetric survey covers Big Sand Wash Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 22 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Big Sand Wash Reservoir?
- Big Sand Wash Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Big Sand State Park.
Can I fish at Big Sand Wash Reservoir?
- Big Sand Wash 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 Utah's fish and wildlife agency, so check its current regulations before you go.
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Where this data comes from
16 measurements from 1 monitoring station, 2017–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Utah Department Of Environmental Quality
UTAHDWQ_WQX16 samples · 2017–2023
Analytical methods
- Field Measurements
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory