Upper Enterprise Reservoir
Washington County, UtahView mapDirections
Nutrients and algae sit mid-range for this region.
↓ down from B at the last regrade
- Mesotrophic
- Impaired · Oxygen depletion (low DO)
- #7 of 10 in the county
- Limited data
Upper Enterprise Reservoir in Washington County, Utah has a water quality grade of C (Fair). Water clarity: 5.2 ft visibility. Phosphorus: 35 µg/L. Chlorophyll-a (algae): 6.4 µg/L.
- Clarity
- 5.2 ft
- Type
- Mesotrophic
- Phosphorus
- 35 µg/L
- Chlorophyll-a
- 6.4 µg/L
- Trend
- ↓ Declining
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Watch Upper Enterprise Reservoir’s letter
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Upper Enterprise Reservoir is a mesotrophic lake in Washington County, Utah. Water quality is graded C based on 2 sampling years through 2021. Overall water quality is declining over recent sampling years. Compared to the 9 other monitored lakes in Washington County, Upper Enterprise Reservoir ranks #7 for water quality.
Source: EPA Water Quality Portal sampling records, Utah DWQ, last sampled 2021-06-23. Grade methodology: LakeQuality methodology.
What Upper Enterprise Reservoir is good for
From access and monitoring records, not editorial picks.
- Camping1 public campground nearby
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. Upper Enterprise 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.
Water Quality Grade: C (Fair)
Murky, only visible to about 5.2 ft. Phosphorus 35 µg/L. Chlorophyll-a 6.4 µg/L. TSI 52. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.2 ft | Not graded |
| Phosphorus | 35 µg/L | Good |
| Chlorophyll-a (Algae) | 6.4 µg/L | Fair |
| Trophic State Index (TSI) | 52 | Mesotrophic |
Moderate nutrients, good water quality
Recreation & Access
Public campgrounds near Upper Enterprise Reservoir
- Honeycomb Rocks Campground0.4 km
Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes
Fishing Upper Enterprise Reservoir
Water Quality Trend: ↓ Declining
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.111 m/yr | 6 |
| Phosphorus | ↓ Declining | +1.3 µg/L/yr | 3 |
| Chlorophyll-a | ↓ Declining | +0.31 µg/L/yr | 3 |
Reservoir Info (USACE NID)
Upper Enterprise Reservoir is a man-made reservoir impounded by the Enterprise (Upper) (completed 1912), built primarily for irrigation on the Little Pine Creek; earth-type dam, 91 ft tall and 190 ft long.
- Normal storage
- 8,690 ac-ft
- Max storage
- 12,300 ac-ft
- Drainage area
- 29.1 sq mi
- Hazard class
- High
- Owner
- ENTERPRISE RESERVOIR & CANAL COMPANY
Source: USACE National Inventory of Dams, NID ID UT00309 · Operator website · Matched by proximity (0.3 km)
EPA Impairment Status
Upper Enterprise Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit UT-L-16030006-002_00 · Official waterbody report
County Ranking
Ranked #7 of 10 lakes in Washington County
Nearby Lakes in Washington County
Frequently asked questions about Upper Enterprise Reservoir
Where is Upper Enterprise Reservoir?
- Upper Enterprise Reservoir is a lake in Washington County, Utah. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Upper Enterprise Reservoir?
- Upper Enterprise Reservoir in Washington County, Utah has a water quality grade of C (Fair). Water clarity: 5.2 ft visibility. Phosphorus: 35 µg/L. Chlorophyll-a (algae): 6.4 µg/L.
Is Upper Enterprise Reservoir safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Upper Enterprise 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.
Are there campgrounds on Upper Enterprise Reservoir?
- Upper Enterprise Reservoir has 1 public campground from USGS The National Map within 5 km, including Honeycomb Rocks Campground. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.
Explore Upper Enterprise Reservoir across LakeQuality
2 thermal springs within 16.4 mi, nearest Veyo Hot 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
Mesotrophic Lakes in Utah
Where this data comes from
72 measurements from 1 monitoring station, 2013–2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Utah Department Of Environmental Quality
UTAHDWQ_WQX72 samples · 2013–2021
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
Public campgrounds from USGS The National Map Structures, within about 3 miles