Horseshoe Reservoir
Big Horn County, Wyoming28 acresView mapDirections
Wyoming DEQ publishes the water-quality measurements for Horseshoe Reservoir. Here is what has been measured.
- Hypereutrophic
- Limited data
Horseshoe Reservoir in Big Horn County, Wyoming has water-quality measurements published by Wyoming DEQ, shown here as reported. Water clarity: 1.8 ft visibility. Phosphorus: 140 µg/L. Surface area: 28 acres.
Horseshoe Reservoir is a 28-acre highly nutrient-loaded hypereutrophic lake in Big Horn County, Wyoming. Overall water quality is improving over recent sampling years. Compared to the 4 other monitored lakes in Big Horn County, Horseshoe Reservoir ranks #4 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 Horseshoe 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 Horseshoe Reservoir
These are the measurements Wyoming DEQ publishes for Horseshoe 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 1.8 ft of visibility. Phosphorus 140 µg/L. TSI 72.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 140µg/L | Poor 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. | 72 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Horseshoe Reservoir
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
28 acres
No bathymetric survey has been published for Horseshoe Reservoir, so its depth is not documented here.
Stays via Stay22
Stays near Horseshoe Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Horseshoe 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. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Horseshoe Reservoir are listed below.
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Fishing Horseshoe 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
Improving-60 µg/L/yr2 years
Reservoir Info (USACE NID)
Horseshoe Reservoir is a man-made reservoir impounded by the Horseshoe (completed 1969), built primarily for fish and wildlife pond on the Trail Draw; earth-type dam, 30 ft tall and 268 ft long.
- Surface area
- 28 ac
- Normal storage
- 145 ac-ft
- Max storage
- 329 ac-ft
- Drainage area
- 0 sq mi
- Hazard class
- Low
- Owner
- WYOMING GAME AND FISH COMMISSION
Source: USACE National Inventory of Dams, NID ID WY01123 · Operator website
Nearby Lakes in Big Horn County
Frequently asked questions about Horseshoe Reservoir
Where is Horseshoe Reservoir?
- Horseshoe 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 Horseshoe Reservoir?
- Horseshoe Reservoir in Big Horn County, Wyoming has water-quality measurements published by Wyoming DEQ, shown here as reported. Water clarity: 1.8 ft visibility. Phosphorus: 140 µg/L. Surface area: 28 acres.
Is Horseshoe Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Explore Horseshoe Reservoir across LakeQuality
16.4 mi away · 200 ft
2 thermal springs within 19.7 mi, nearest Little Sheep Mountain Spring
Species activity outlook by water temperature and season
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Where this data comes from
7 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_WATERSHED7 samples · 2015–2016
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.