Calder Reservoir
Uintah County, UtahView mapDirections
Nutrients and algae sit mid-range for this region.
↓ down from B at the last regrade
- Mesotrophic
- Impaired · Ammonia
- #9 of 14 in the county
- 14 ft max depth
- Public access
- Limited data
Calder Reservoir in Uintah County, Utah has a water quality grade of C (Fair). Water clarity: 8.9 ft visibility. Phosphorus: 256 µg/L. Chlorophyll-a (algae): 3.7 µg/L.
- Clarity
- 8.9 ft
- Max depth
- ~14 ft est.
- Type
- Mesotrophic
- Phosphorus
- 256 µg/L
- Chlorophyll-a
- 3.7 µg/L
- Trend
- ↑ Improving
- Public access
- Yes
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Watch Calder Reservoir’s letter
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Calder Reservoir is a mesotrophic lake in Uintah County, Utah with an estimated average depth of about 14 feet. Water quality is graded C based on 2 sampling years through 2023. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 13 other monitored lakes in Uintah County, Calder Reservoir ranks #9 for water quality.
Source: EPA Water Quality Portal sampling records, Utah DWQ, last sampled 2023-10-03. Grade methodology: LakeQuality methodology.
What Calder Reservoir is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
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. Calder Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for ammonia, nutrients (phosphorus, nitrogen), oxygen depletion (low DO), pH / acidity, temperature. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Moderate clarity, visible to about 8.9 ft. Phosphorus 256 µg/L. Chlorophyll-a 3.7 µg/L. TSI 58. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.9 ft | Not graded |
| Phosphorus | 256 µg/L | Poor |
| Chlorophyll-a (Algae) | 3.7 µg/L | Good |
| Trophic State Index (TSI) | 58 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~14 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Utah has not published bathymetry for Calder 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.
Recreation & Access
- Calder ReservoirPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Calder Reservoir
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.097 m/yr | 5 |
| Chlorophyll-a | ↑ Improving | -3.62 µg/L/yr | 3 |
Reservoir Info (USACE NID)
Calder Reservoir is a man-made reservoir impounded by the Calder (Zelph) (completed 1989), built primarily for irrigation on the Pot Creek; earth-type dam, 50 ft tall and 374 ft long.
- Normal storage
- 1,600 ac-ft
- Max storage
- 2,600 ac-ft
- Drainage area
- 35 sq mi
- Hazard class
- Significant
- Owner
- DIVISION OF WILDLIFE RESOURCES
Source: USACE National Inventory of Dams, NID ID UT00061 · Operator website · Matched by proximity (0.3 km)
EPA Impairment Status
Calder Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit UT-L-14040106-034_00 · Official waterbody report
County Ranking
Ranked #9 of 14 lakes in Uintah County
Nearby Lakes With Higher Grades
Calder Reservoir holds Grade C. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Uintah County
Frequently asked questions about Calder Reservoir
Where is Calder Reservoir?
- Calder Reservoir is a lake in Uintah County, Utah. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Calder Reservoir?
- Calder Reservoir in Uintah County, Utah has a water quality grade of C (Fair). Water clarity: 8.9 ft visibility. Phosphorus: 256 µg/L. Chlorophyll-a (algae): 3.7 µg/L.
Is Calder Reservoir safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Calder Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for ammonia, nutrients (phosphorus, nitrogen), oxygen depletion (low DO), pH / acidity, temperature. Check local advisories before you swim.
How deep is Calder Reservoir?
- No published bathymetric survey covers Calder Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 14 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Calder Reservoir?
- Calder Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Calder Reservoir. Public access is listed as yes.
Explore Calder Reservoir across LakeQuality
18.4 mi away · recorded at 86°F
Species activity outlook by water temperature and season
Where to stay at Utah's top lakes, each with its grade
Moderate nutrients, good water quality
Utah's cleanest and most-polluted lakes, ranked
Planning a trip around Dinosaur?
Calder Reservoir is about 21 miles from Dinosaur National Monument. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Dinosaur →More Utah Lake Rankings
Other Grade C Lakes in Utah
Mesotrophic Lakes in Utah
Where this data comes from
46 measurements from 1 monitoring station, 2012–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Utah Department Of Environmental Quality
UTAHDWQ_WQX46 samples · 2012–2023
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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory