Twin Lakes Reservoir D
Sheridan County, Wyoming81 acresView mapDirections
Clarity, phosphorus, and algae sit in the clean band for this region.
↓ down from A at the last regrade
- Oligotrophic
- #5 of 5 in the county
- 13 ft max depth
- Limited data
Twin Lakes Reservoir D in Sheridan County, Wyoming has a water quality grade of B (Good). Phosphorus: 10 µg/L. Surface area: 81 acres.
- Max depth
- ~13 ft est.
- Area
- 81 acres
- Type
- Oligotrophic
- Phosphorus
- 10 µg/L
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Twin Lakes Reservoir D is a 81-acre cold, clear oligotrophic lake in Sheridan County, Wyoming with an estimated average depth of about 13 feet. Water quality is graded B based on 1 sampling years through 2017. Compared to the 4 other monitored lakes in Sheridan County, Twin Lakes Reservoir D ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, Wyoming DEQ, last sampled 2017-09-12. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The B is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: B (Good)
No clarity data. Phosphorus 10 µg/L. TSI 37. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 10 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 37 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~13 ft est. |
| Surface Area | 81 acres |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Wyoming has not published bathymetry for Twin Lakes Reservoir D.
Lake Size & Watershed
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.
Fishing Twin Lakes Reservoir D
Reservoir Info (USACE NID)
Twin Lakes Reservoir D is a man-made reservoir impounded by the Twin Lakes No. 1 (completed 1998), built primarily for water supply on the Coney Creek; earth-type dam, 91 ft tall and 1,835 ft long.
- Surface area
- 81 ac
- Normal storage
- 3,411 ac-ft
- Max storage
- 4,041 ac-ft
- Drainage area
- 8.3 sq mi
- Hazard class
- High
- Owner
- CITY OF SHERIDAN - TOM MANOLIS
Source: USACE National Inventory of Dams, NID ID WY00647 · Operator website · Matched by proximity (0.21 km)
County Ranking
Ranked #5 of 5 lakes in Sheridan County
Nearby Lakes in Sheridan County
Frequently asked questions about Twin Lakes Reservoir D
Where is Twin Lakes Reservoir D?
- Twin Lakes Reservoir D is a lake in Sheridan County, Wyoming. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Twin Lakes Reservoir D?
- Twin Lakes Reservoir D in Sheridan County, Wyoming has a water quality grade of B (Good). Phosphorus: 10 µg/L. Surface area: 81 acres.
Is Twin Lakes Reservoir D safe to swim in?
- The B is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is Twin Lakes Reservoir D?
- No published bathymetric survey covers Twin Lakes Reservoir D, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 13 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 81 acres.
Explore Twin Lakes Reservoir D across LakeQuality
14.9 mi away · 120 ft
Species activity outlook by water temperature and season
Where to stay at Wyoming's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
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Where this data comes from
3 measurements from 1 monitoring station, 2017. 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 · 2017
Analytical methods
- 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
Lake size & watershed from HydroLAKES (HydroSHEDS)