Unnamed Reservoir
Big Horn County, Wyoming34 acresView mapDirections
Wyoming DEQ publishes the water-quality measurements for Unnamed Reservoir. Here is what has been measured.
- Eutrophic
- Limited data
Unnamed Reservoir in Big Horn County, Wyoming has water-quality measurements published by Wyoming DEQ, shown here as reported. Phosphorus: 65 µg/L. Surface area: 34 acres.
Unnamed Reservoir is a 34-acre productive, nutrient-rich eutrophic lake in Big Horn County, Wyoming. Overall water quality is declining over recent sampling years. Compared to the 4 other monitored lakes in Big Horn County, Unnamed Reservoir ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Wyoming DEQ, last sampled 2016-09-20. Methodology: how these readings are compared.
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 Unnamed 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 Unnamed Reservoir
These are the measurements Wyoming DEQ publishes for Unnamed Reservoir, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. Phosphorus 65 µg/L. TSI 64.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | No reading How deep a black-and-white disk stays visible from the surface. Higher is clearer. | |
| Total phosphorus | 65µg/L | Fair GoodFairPoor |
| 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. | 64 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Unnamed Reservoir
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
34 acres
No bathymetric survey has been published for Unnamed Reservoir, so its depth is not documented here.
Stays via Stay22
Stays near Unnamed Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Unnamed Reservoir in Big Horn County, Wyoming — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Unnamed Reservoir
Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Wyoming’s top lakes →
Follow Unnamed Reservoir’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Unnamed Reservoir
Water quality readings over time
2 seasons of samples on record (2015–2016). Calling a direction takes at least 4 years of the same measurement.
Phosphorus
Worsening+5 µg/L/yr2 years
Reservoir Info (USACE NID)
Unnamed Reservoir is a man-made reservoir impounded by the Bench Canal (completed 1969), built primarily for irrigation on the Greybull River; earth-type dam, 35 ft tall and 1,000 ft long.
- Surface area
- 34 ac
- Normal storage
- 299 ac-ft
- Max storage
- 497 ac-ft
- Drainage area
- 1 sq mi
- Hazard class
- Low
- Owner
- BENCH CANAL COMPANY
Source: USACE National Inventory of Dams, NID ID WY01086 · Operator website · Matched by proximity (0.27 km)
Nearby Lakes in Big Horn County
Frequently asked questions about Unnamed Reservoir
Where is Unnamed Reservoir?
- Unnamed Reservoir is a lake in Big Horn County, Wyoming. Its water-quality measurements are published by Wyoming DEQ and shown on this page as reported.
What is the water quality of Unnamed Reservoir?
- Unnamed Reservoir in Big Horn County, Wyoming has water-quality measurements published by Wyoming DEQ, shown here as reported. Phosphorus: 65 µg/L. Surface area: 34 acres.
Is Unnamed Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Explore Unnamed Reservoir across LakeQuality
More lakes in Wyoming
Other Lakes in Wyoming
Eutrophic Lakes in Wyoming
Where this data comes from
12 measurements from 1 monitoring station, 2015–2016. 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_WATERSHED12 samples · 2015–2016
Analytical methods
- 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.