Sawmill Reservoir D
Sheridan County, Wyoming75 acresView mapDirections
Clarity, phosphorus, and algae sit in the clean band for this region.
- Mesotrophic
- #4 of 5 in the county
- 15 ft max depth
- Limited data
Sawmill Reservoir D in Sheridan County, Wyoming has a water quality grade of B (Good). Phosphorus: 20 µg/L. Surface area: 75 acres.
- Max depth
- ~15 ft est.
- Area
- 75 acres
- Type
- Mesotrophic
- Phosphorus
- 20 µg/L
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Watch Sawmill Reservoir D’s letter
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Sawmill Reservoir D is a 75-acre mesotrophic lake in Sheridan County, Wyoming with an estimated average depth of about 15 feet. Water quality is graded B based on 1 sampling years through 2017. Compared to the 4 other monitored lakes in Sheridan County, Sawmill Reservoir D ranks #4 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 20 µg/L. TSI 47. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 20 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 47 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~15 ft est. |
| Surface Area | 75 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 Sawmill 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 Sawmill Reservoir D
Reservoir Info (USACE NID)
Sawmill Reservoir D is a man-made reservoir impounded by the Sawmill (completed 1972), built primarily for irrigation on the Sawmill Creek; earth-type dam, 38 ft tall and 517 ft long.
- Surface area
- 75 ac
- Normal storage
- 1,275 ac-ft
- Max storage
- 1,831 ac-ft
- Drainage area
- 8.3 sq mi
- Hazard class
- High
- Owner
- SAWMILL RESERVOIR COMPANY (DON ROBERTS)
Source: USACE National Inventory of Dams, NID ID WY00677 · Operator website · Matched by proximity (0.15 km)
County Ranking
Ranked #4 of 5 lakes in Sheridan County
Nearby Lakes in Sheridan County
Frequently asked questions about Sawmill Reservoir D
Where is Sawmill Reservoir D?
- Sawmill 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 Sawmill Reservoir D?
- Sawmill Reservoir D in Sheridan County, Wyoming has a water quality grade of B (Good). Phosphorus: 20 µg/L. Surface area: 75 acres.
Is Sawmill 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 Sawmill Reservoir D?
- No published bathymetric survey covers Sawmill Reservoir D, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 15 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 75 acres.
Explore Sawmill Reservoir D across LakeQuality
15.6 mi away · 120 ft
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Moderate nutrients, good water quality
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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)