Mona Reservoir
Juab County, UtahView mapDirections
Nutrients and algae sit mid-range for this region.
- Mesotrophic
- #1 of 3 in the county
- 50 ft max depth
Mona Reservoir in Juab County, Utah has a water quality grade of C (Fair). Water clarity: 2 ft visibility. Phosphorus: 53.5 µg/L. Chlorophyll-a (algae): 4.3 µg/L.
- Clarity
- 2 ft
- Max depth
- ~50 ft est.
- Type
- Mesotrophic
- Phosphorus
- 53.5 µg/L
- Chlorophyll-a
- 4.3 µg/L
- Trend
- ↑ Improving
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Watch Mona Reservoir’s letter
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Mona Reservoir is a mesotrophic lake in Juab County, Utah with an estimated average depth of about 50 feet. Water quality is graded C based on 2 sampling years through 2024. Overall water quality is improving over recent sampling years. Public access is available with 1 public boat landing. Compared to the 2 other monitored lakes in Juab County, Mona Reservoir ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Utah DWQ, last sampled 2024-09-05. Grade methodology: LakeQuality methodology.
What Mona Reservoir is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming Safety
Grade onlyModerate
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 2 ft of visibility. Phosphorus 53.5 µg/L. Chlorophyll-a 4.3 µg/L. TSI 58. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2 ft | Not graded |
| Phosphorus | 53.5 µg/L | Fair |
| Chlorophyll-a (Algae) | 4.3 µg/L | Good |
| Trophic State Index (TSI) | 58 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~50 ft est. |
| Average Depth | ~18 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 Mona 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
- Mona ReservoirSemi-private
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Mona Reservoir
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.088 m/yr | 2 |
| Chlorophyll-a | → Stable | -0.05 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Mona Reservoir is a man-made reservoir impounded by the Mona (completed 1895), built primarily for irrigation on the Current Creek; earth-type dam, 28 ft tall and 214 ft long.
- Normal storage
- 19,190 ac-ft
- Max storage
- 30,000 ac-ft
- Drainage area
- 157 sq mi
- Hazard class
- High
- Owner
- CURRENT CREEK IRRIGATION COMPANY
Source: USACE National Inventory of Dams, NID ID UT00215 · Operator website
County Ranking
Ranked #1 of 3 lakes in Juab County
Nearby Lakes in Juab County
Frequently asked questions about Mona Reservoir
Where is Mona Reservoir?
- Mona Reservoir is a lake in Juab County, Utah. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Mona Reservoir?
- Mona Reservoir in Juab County, Utah has a water quality grade of C (Fair). Water clarity: 2 ft visibility. Phosphorus: 53.5 µg/L. Chlorophyll-a (algae): 4.3 µg/L.
Is Mona Reservoir safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is Mona Reservoir?
- No published bathymetric survey covers Mona Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 50 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 Mona Reservoir?
- Mona Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Mona Reservoir.
Explore Mona Reservoir across LakeQuality
2 thermal springs within 6.2 mi, nearest Ray Lunt Spring
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
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Other Grade C Lakes in Utah
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Where this data comes from
30 measurements from 2 monitoring stations, 2012–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Utah Department Of Environmental Quality
UTAHDWQ_WQX30 samples · 2012–2024
Analytical methods
- Field Measurements
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (2)
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)
Named boat-access points from the USGS National Boat Ramps inventory