Gunnison Reservoir
Sanpete County, UtahView mapDirections
Nutrients and algae sit mid-range for this region.
- Eutrophic
- #10 of 11 in the county
- 75 ft max depth
- Limited data
Gunnison Reservoir in Sanpete County, Utah has a water quality grade of C (Fair). Water clarity: 0.8 ft visibility. Phosphorus: 113.5 µg/L. Chlorophyll-a (algae): 8.2 µg/L.
- Clarity
- 0.8 ft
- Max depth
- ~75 ft est.
- Type
- Eutrophic
- Phosphorus
- 113.5 µg/L
- Chlorophyll-a
- 8.2 µg/L
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Watch Gunnison Reservoir’s letter
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Gunnison Reservoir is a productive, nutrient-rich eutrophic lake in Sanpete County, Utah with an estimated average depth of about 75 feet. Water quality is graded C based on 1 sampling years through 2020. Compared to the 10 other monitored lakes in Sanpete County, Gunnison Reservoir ranks #10 for water quality.
Source: EPA Water Quality Portal sampling records, Utah DWQ, last sampled 2020-08-04. 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 C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Very murky, less than 0.8 ft of visibility. Phosphorus 113.5 µg/L. Chlorophyll-a 8.2 µg/L. TSI 68. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.8 ft | Not graded |
| Phosphorus | 113.5 µg/L | Not graded |
| Chlorophyll-a (Algae) | 8.2 µg/L | Fair |
| Trophic State Index (TSI) | 68 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~75 ft est. |
| Average Depth | ~19 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 Gunnison Reservoir.
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 Gunnison Reservoir
Reservoir Info (USACE NID)
Gunnison Reservoir is a man-made reservoir impounded by the Gunnison (completed 1889), built primarily for irrigation on the San Pitch River; earth-type dam, 42 ft tall and 1,240 ft long.
- Normal storage
- 12,800 ac-ft
- Max storage
- 33,000 ac-ft
- Drainage area
- 670 sq mi
- Hazard class
- High
- Owner
- GUNNISON IRRIGATION COMPANY
Source: USACE National Inventory of Dams, NID ID UT00130 · Operator website
County Ranking
Ranked #10 of 11 lakes in Sanpete County
Nearby Lakes in Sanpete County
Frequently asked questions about Gunnison Reservoir
Where is Gunnison Reservoir?
- Gunnison Reservoir is a lake in Sanpete County, Utah. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Gunnison Reservoir?
- Gunnison Reservoir in Sanpete County, Utah has a water quality grade of C (Fair). Water clarity: 0.8 ft visibility. Phosphorus: 113.5 µg/L. Chlorophyll-a (algae): 8.2 µg/L.
Is Gunnison Reservoir safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is Gunnison Reservoir?
- No published bathymetric survey covers Gunnison Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 75 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Gunnison Reservoir across LakeQuality
3 thermal springs within 16.9 mi, nearest Sterling (Peacock) Warm Spring
Species activity outlook by water temperature and season
Where to stay at Utah's top lakes, each with its grade
High nutrients, frequent algae, reduced clarity
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Where this data comes from
10 measurements from 1 monitoring station, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Utah Department Of Environmental Quality
UTAHDWQ_WQX10 samples · 2020
Analytical methods
- Field Measurements
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
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)