Miller Flat Reservoir
Emery County, UtahView mapDirections
Nutrients and algae run above the regional average.
↓ down from A at the last regrade
- Mesotrophic
- #10 of 10 in the county
- Limited data
Miller Flat Reservoir in Emery County, Utah has a water quality grade of D (Nutrient-rich). Water clarity: 10.2 ft visibility. Phosphorus: 13.5 µg/L. Chlorophyll-a (algae): 4.5 µg/L.
- Clarity
- 10.2 ft
- Type
- Mesotrophic
- Phosphorus
- 13.5 µg/L
- Chlorophyll-a
- 4.5 µg/L
- Trend
- ↓ Declining
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Stays near Miller Flat Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Miller Flat Reservoir in Emery County, Utah — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Miller Flat Reservoir are listed below.
Top-rated places to stay near Miller Flat Reservoir
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Watch Miller Flat Reservoir’s letter
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Miller Flat Reservoir is a mesotrophic lake in Emery County, Utah. Water quality is graded D based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. Compared to the 9 other monitored lakes in Emery County, Miller Flat Reservoir ranks #10 for water quality.
Source: EPA Water Quality Portal sampling records, Utah DWQ, last sampled 2025-09-23. Grade methodology: LakeQuality methodology.
What Miller Flat Reservoir is good for
From access and monitoring records, not editorial picks.
- Clear water10.2 ft of visibility
- 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 D is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
Good clarity, visible to about 10.2 ft. Phosphorus 13.5 µg/L. Chlorophyll-a 4.5 µg/L. TSI 44. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.2 ft | Not graded |
| Phosphorus | 13.5 µg/L | Good |
| Chlorophyll-a (Algae) | 4.5 µg/L | Poor |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Recreation & Access
Public campgrounds near Miller Flat Reservoir
- Miller Flat Reservoir Cg2.1 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 Miller Flat Reservoir
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.525 m/yr | 2 |
| Chlorophyll-a | → Stable | 0 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Miller Flat Reservoir is a man-made reservoir impounded by the Miller Flat (completed 1949), built primarily for irrigation on the Miller Flat Creek; earth-type dam, 73 ft tall and 835 ft long.
- Normal storage
- 5,560 ac-ft
- Max storage
- 6,393 ac-ft
- Drainage area
- 9 sq mi
- Hazard class
- High
- Owner
- HUNTINGTON-CLEVELAND IRRIGATION COMPANY
Source: USACE National Inventory of Dams, NID ID UT00210 · Operator website
County Ranking
Ranked #10 of 10 lakes in Emery County
Nearby Lakes in Emery County
Frequently asked questions about Miller Flat Reservoir
Where is Miller Flat Reservoir?
- Miller Flat Reservoir is a lake in Emery County, Utah. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Miller Flat Reservoir?
- Miller Flat Reservoir in Emery County, Utah has a water quality grade of D (Nutrient-rich). Water clarity: 10.2 ft visibility. Phosphorus: 13.5 µg/L. Chlorophyll-a (algae): 4.5 µg/L.
Is Miller Flat Reservoir safe to swim in?
- The D is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Are there campgrounds on Miller Flat Reservoir?
- Miller Flat Reservoir has 1 public campground from USGS The National Map within 5 km, including Miller Flat Reservoir Cg. 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 Miller Flat Reservoir across LakeQuality
More Utah Lake Rankings
Other Grade D Lakes in Utah
Mesotrophic Lakes in Utah
Where this data comes from
17 measurements from 1 monitoring station, 2019–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Utah Department Of Environmental Quality
UTAHDWQ_WQX17 samples · 2019–2025
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
Public campgrounds from USGS The National Map Structures, within about 3 miles