Grantsville Reservoir
Tooele County, UtahView mapDirections
Utah DWQ publishes the water-quality measurements for Grantsville Reservoir. Here is what has been measured.
- Mesotrophic
- Impaired · Oxygen depletion (low DO)
- 24 ft max depth
- Limited data
Grantsville Reservoir in Tooele County, Utah has water-quality measurements published by Utah DWQ, shown here as reported. Water clarity: 5.9 ft visibility. Phosphorus: 19 µg/L. Chlorophyll-a (algae): 4 µg/L.
Grantsville Reservoir is a mesotrophic lake in Tooele County, Utah with an estimated average depth of about 24 feet. Water clarity is improving over recent sampling years. Compared to the 3 other monitored lakes in Tooele County, Grantsville Reservoir ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Utah DWQ, last sampled 2024-09-03. Methodology: how these readings are compared.
If you are planning to stay, you can search lake houses and cabins around Grantsville Reservoir on Vrbo, or look for a hotel room near the lake on Booking.com or Expedia.
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Grantsville Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for oxygen depletion (low DO), pH / acidity, temperature. Check local advisories before you swim.
Whether Grantsville Reservoir is safe to swim in today is a call for the Utah Division of Water Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Grantsville Reservoir
These are the measurements Utah DWQ publishes for Grantsville Reservoir, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 5.9 ft. Phosphorus 19 µg/L. Chlorophyll-a 4 µg/L. TSI 47.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 5.9ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 19µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 4µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 47 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Grantsville Reservoir
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Lake Details
Max depth
~24 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 Grantsville Reservoir.
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Surface area
64 acres
HydroLAKES / HydroSHEDS
Shoreline
1.3 mi
HydroLAKES / HydroSHEDS
Elevation
5,030 ft
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.
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Stays near Grantsville Reservoir
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Fishing Grantsville Reservoir
Water quality readings over time
3 seasons of samples on record (2012–2024). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving3 years
Chlorophyll-a
Worsening+0.11 µg/L/yr2 years
Reservoir Info (USACE NID)
Grantsville Reservoir is a man-made reservoir impounded by the Grantsville (completed 1984), built primarily for irrigation on the So Willow, No Willow, Et Al; earth-type dam, 82 ft tall and 5,376 ft long.
- Normal storage
- 3,370 ac-ft
- Max storage
- 3,885 ac-ft
- Drainage area
- 3 sq mi
- Hazard class
- High
- Owner
- GRANTSVILLE IRRIGATION COMPANY
Source: USACE National Inventory of Dams, NID ID UT00343 · Operator website
EPA Impairment Status
Grantsville Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Aquatic life.
Source: EPA ATTAINS assessment unit UT-L-16020304-005_00 · Official waterbody report
Nearby Lakes in Tooele County
Frequently asked questions about Grantsville Reservoir
Where is Grantsville Reservoir?
- Grantsville Reservoir is a lake in Tooele County, Utah. Its water-quality measurements are published by Utah DWQ and shown on this page as reported.
What is the water quality of Grantsville Reservoir?
- Grantsville Reservoir in Tooele County, Utah has water-quality measurements published by Utah DWQ, shown here as reported. Water clarity: 5.9 ft visibility. Phosphorus: 19 µg/L. Chlorophyll-a (algae): 4 µg/L.
Is Grantsville Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Grantsville Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for oxygen depletion (low DO), pH / acidity, temperature. Check local advisories before you swim.
How deep is Grantsville Reservoir?
- No published bathymetric survey covers Grantsville Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 24 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
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Where this data comes from
19 measurements from 1 monitoring station, 2012–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Utah Department Of Environmental Quality
UTAHDWQ_WQX19 samples · 2012–2024
Analytical methods
- Field Measurements
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)