Mirror Lake
Adams County, North Dakota94 acresView mapDirections
ND DEQ publishes the water-quality measurements for Mirror Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- 13 ft max depth
- Public access
Mirror Lake in Adams County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. Water clarity: 2.1 ft visibility. Phosphorus: 388 µg/L. Chlorophyll-a (algae): 31.6 µg/L. Surface area: 94.33 acres.
Mirror Lake is a 94-acre highly nutrient-loaded hypereutrophic lake in Adams County, North Dakota with an estimated average depth of about 13 feet. 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 1 other monitored lakes in Adams County, Mirror Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, NDDEQ, last sampled 2024-09-24. Methodology: how these readings are compared.
What Mirror Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
Readings onlyAlgae risk
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. Mirror Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen), oxygen depletion (low DO). Check local advisories before you swim.
Whether Mirror Lake is safe to swim in today is a call for the North Dakota Department of Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Mirror Lake
These are the measurements ND DEQ publishes for Mirror Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 2.1 ft of visibility. Phosphorus 388 µg/L. Chlorophyll-a 31.6 µg/L. TSI 74.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 2.1ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 388µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 31.6µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 74 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Mirror Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Mirror Lake typically sits around 47°F at the surface in October. Summer average is about 59°F. Usually warmest in Jun (about 61°F) and coldest in Oct (about 47°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (47°F) to its warmest (61°F).
Typical surface water temperature by month, from 23 field readings (2023–2023) via the EPA Water Quality Portal. See the full Mirror Lake water temperature breakdown →
Lake Details
Max depth
~13 ft est.
Surface area
94 acres
Public access
Yes
Listed by ND DEQ
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. North Dakota has not published bathymetry for Mirror Lake.
Lake Size & Watershed
Watershed (drainage) area
69 sq mi
HydroLAKES / HydroSHEDS
Shoreline
1.2 mi
HydroLAKES / HydroSHEDS
Elevation
2,648 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.
Recreation & Access
- Mirror LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Mirror Lake
Compare lakeside cabins, hotels, and vacation rentals near Mirror Lake in Adams County, North Dakota — 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 readings cover nutrients and algae, not lodging. Cabins and rentals around Mirror Lake are listed below.
Top-rated places to stay near Mirror Lake
Prices for Oct 23–25, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at North Dakota’s top lakes →
Follow Mirror Lake’s readings
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Fishing Mirror Lake
Water quality readings over time
2 seasons of samples on record (2023–2024). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Worsening2 years
Phosphorus
Improving-179.5 µg/L/yr2 years
Chlorophyll-a
Worsening+31 µg/L/yr2 years
Reservoir Info (USACE NID)
Mirror Lake is a man-made reservoir impounded by the Mirror Lake Dam (completed 1909), built primarily for recreation on the Flat Creek; earth-type dam, 19 ft tall and 800 ft long.
- Surface area
- 94.33 ac
- Normal storage
- 573 ac-ft
- Max storage
- 894.59 ac-ft
- Drainage area
- 0 sq mi
- Hazard class
- Significant
- Owner
- Hettinger Park Board
Source: USACE National Inventory of Dams, NID ID ND00137 · Operator website
EPA Impairment Status
Mirror Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit ND-10130303-001-L_00 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Mirror Lake under Clean Water Act (NPDES) discharge permits.
- Hettinger City OfHettinger · 1.9 mi away · NPDES ND0022497
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Nearby Lakes in Adams County
Frequently asked questions about Mirror Lake
Where is Mirror Lake?
- Mirror Lake is a lake in Adams County, North Dakota. Its water-quality measurements are published by ND DEQ and shown on this page as reported.
What is the water quality of Mirror Lake?
- Mirror Lake in Adams County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. Water clarity: 2.1 ft visibility. Phosphorus: 388 µg/L. Chlorophyll-a (algae): 31.6 µg/L. Surface area: 94.33 acres.
Is Mirror Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Mirror Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen), oxygen depletion (low DO). Check local advisories before you swim.
What is the water temperature of Mirror Lake?
- Mirror Lake typically sits around 47°F at the surface in October, from 23 EPA Water Quality Portal field readings (2023–2023). That is a typical value for the month, not a live reading.
How deep is Mirror Lake?
- No published bathymetric survey covers Mirror Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 13 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 94.33 acres.
Are there boat ramps on Mirror Lake?
- Mirror Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Mirror Lake. Public access is listed as yes.
Can I fish at Mirror Lake?
- Mirror Lake 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 North Dakota's fish and wildlife agency, so check its current regulations before you go.
Explore Mirror Lake across LakeQuality
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Where this data comes from
49 measurements from 2 monitoring stations, 2023–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North Dakota Department Of Environmental Quality
21NDHDWQ_WQX49 samples · 2023–2024
Analytical methods
- Phosphorus by Colorimetry
- 447.0 ~ EPA; Chlorophyll a and b in phytoplankton by HPLC/UV
- 4500 NO3 E ~ Nitrate in Water- Cadmium Reduction
Monitoring station identifiers (2)
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Depth, fish, and access data from North Dakota Game & Fish
Named boat-access points from the USGS National Boat Ramps inventory