Millsite Reservoir
Emery County, UtahView mapDirections
Utah DWQ publishes the water-quality measurements for Millsite Reservoir. Here is what has been measured.
- Oligotrophic
- Public access
- Limited data
Millsite Reservoir in Emery County, Utah has water-quality measurements published by Utah DWQ, shown here as reported. Water clarity: 10.5 ft visibility. Phosphorus: 20.6 µg/L. Chlorophyll-a (algae): 1.9 µg/L.
Millsite Reservoir is a cold, clear oligotrophic lake in Emery County, Utah. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 9 other monitored lakes in Emery County, Millsite Reservoir ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Utah DWQ, last sampled 2025-10-01. Methodology: how these readings are compared.
What Millsite Reservoir is good for
From access and monitoring records, not editorial picks.
- Clear water10.5 ft of visibility
- Boat launch1 documented ramp
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. Check local advisories before you swim.
Whether Millsite 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 Millsite Reservoir
These are the measurements Utah DWQ publishes for Millsite Reservoir, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 10.5 ft. Phosphorus 20.6 µg/L. Chlorophyll-a 1.9 µg/L. TSI 43.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 10.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 20.6µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 1.9µg/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. | 43 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Millsite Reservoir
Answers come straight from the public measurements and survey records on this page.
Recreation & Access
- Millsite State ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Millsite Reservoir
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Fishing Millsite Reservoir
Water Quality Trend: Worsening
Based on 4 years of monitoring (2012–2025).
Water clarity
Worsening4 years
Chlorophyll-a
Worsening+0.05 µg/L/yr3 years
Reservoir Info (USACE NID)
Millsite Reservoir is a man-made reservoir impounded by the Millsite (completed 1971), built primarily for irrigation on the Ferron Creek; earth-type dam, 115 ft tall and 4,150 ft long.
- Normal storage
- 18,000 ac-ft
- Max storage
- 20,000 ac-ft
- Drainage area
- 157 sq mi
- Hazard class
- High
- Owner
- FERRON CANAL AND RESERVOIR COMPANY
Source: USACE National Inventory of Dams, NID ID UT00212 · Operator website
Nearby Lakes in Emery County
Frequently asked questions about Millsite Reservoir
Where is Millsite Reservoir?
- Millsite Reservoir is a lake in Emery County, Utah. Its water-quality measurements are published by Utah DWQ and shown on this page as reported.
What is the water quality of Millsite Reservoir?
- Millsite Reservoir in Emery County, Utah has water-quality measurements published by Utah DWQ, shown here as reported. Water clarity: 10.5 ft visibility. Phosphorus: 20.6 µg/L. Chlorophyll-a (algae): 1.9 µg/L.
Is Millsite Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Are there boat ramps on Millsite Reservoir?
- Millsite Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Millsite State Park. Public access is listed as yes.
Can I fish at Millsite Reservoir?
- Millsite Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Utah's fish and wildlife agency, so check its current regulations before you go.
Explore Millsite Reservoir across LakeQuality
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Other Lakes in Utah
Oligotrophic Lakes in Utah
Where this data comes from
59 measurements from 1 monitoring station, 2013–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Utah Department Of Environmental Quality
UTAHDWQ_WQX59 samples · 2013–2025
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
Named boat-access points from the USGS National Boat Ramps inventory