Larson Lake
Hettinger County, North Dakota235 acresView mapDirections
Nutrients and algae run above the regional average.
↓ down from C at the last regrade
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- #3 of 3 in the county
- 10 ft max depth
- Public access
- Limited data
Larson Lake in Hettinger County, North Dakota has a water quality grade of D (Nutrient-rich). Water clarity: 4.8 ft visibility. Phosphorus: 613 µg/L. Chlorophyll-a (algae): 13.1 µg/L. Surface area: 235 acres.
- Clarity
- 4.8 ft
- Typical in October
- 48°F
- Max depth
- ~10 ft est.
- Area
- 235 acres
- Type
- Eutrophic
- Public access
- Yes
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Compare lakeside cabins, hotels, and vacation rentals near Larson Lake in Hettinger 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 grade measures nutrients and algae, not lodging — cabins and rentals around Larson Lake are listed below.
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Larson Lake is a 235-acre productive, nutrient-rich eutrophic lake in Hettinger County, North Dakota with an estimated average depth of about 10 feet. Water quality is graded D based on 1 sampling years through 2023. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 2 other monitored lakes in Hettinger County, Larson Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, NDDEQ, last sampled 2023-10-10. Grade methodology: LakeQuality methodology.
What Larson Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
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. Larson Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), oxygen depletion (low DO). Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
Murky, only visible to about 4.8 ft. Phosphorus 613 µg/L. Chlorophyll-a 13.1 µg/L. TSI 69. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.8 ft | Not graded |
| Phosphorus | 613 µg/L | Not graded |
| Chlorophyll-a (Algae) | 13.1 µg/L | Not graded |
| Trophic State Index (TSI) | 69 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Temperature
Larson Lake typically sits around 48°F at the surface in October. Summer average is about 67°F. Usually warmest in Jul (about 72°F) and coldest in Oct (about 48°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 20 field readings (2014–2023) via the EPA Water Quality Portal. See the full Larson Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~10 ft est. |
| Average Depth | ~6 ft est. |
| Surface Area | 235 acres |
| Public Access | Yes |
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 Larson Lake.
Lake Size & Watershed
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
- Larson LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Larson Lake
Reservoir Info (USACE NID)
Larson Lake is a man-made reservoir impounded by the Regent Dam - Spring Creek Dam (completed 1934), built primarily for recreation on the Cannonball River - TR; earth-type dam, 21 ft tall and 395 ft long.
- Surface area
- 235 ac
- Normal storage
- 1,210 ac-ft
- Max storage
- 3,470 ac-ft
- Drainage area
- 31.5 sq mi
- Hazard class
- Low
- Owner
- Hettinger County WRB
Source: USACE National Inventory of Dams, NID ID ND00118 · Operator website
EPA Impairment Status
Larson Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit ND-10130204-002-L_00 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Larson Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Regent City OfRegent · 1.8 mi away · NPDES ND0020532Recent violation
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.
County Ranking
Ranked #3 of 3 lakes in Hettinger County
Nearby Lakes in Hettinger County
Frequently asked questions about Larson Lake
Where is Larson Lake?
- Larson Lake is a lake in Hettinger County, North Dakota. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Larson Lake?
- Larson Lake in Hettinger County, North Dakota has a water quality grade of D (Nutrient-rich). Water clarity: 4.8 ft visibility. Phosphorus: 613 µg/L. Chlorophyll-a (algae): 13.1 µg/L. Surface area: 235 acres.
Is Larson Lake safe to swim in?
- The D is nutrients and algae, not a swimming clearance. Larson Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), oxygen depletion (low DO). Check local advisories before you swim.
What is the water temperature of Larson Lake?
- Larson Lake typically sits around 48°F at the surface in October, from 20 EPA Water Quality Portal field readings (2014–2023). That is a typical value for the month, not a live reading.
How deep is Larson Lake?
- No published bathymetric survey covers Larson Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 10 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 235 acres.
Are there boat ramps on Larson Lake?
- Larson Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Larson Lake. Public access is listed as yes.
Explore Larson Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Species activity outlook by water temperature and season
Where to stay at North Dakota's top lakes, each with its grade
High nutrients, frequent algae, reduced clarity
North Dakota's cleanest and most-polluted lakes, ranked
More North Dakota Lake Rankings
Other Grade D Lakes in North Dakota
Eutrophic Lakes in North Dakota
Where this data comes from
21 measurements from 1 monitoring station, 2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North Dakota Department Of Environmental Quality
21NDHDWQ_WQX21 samples · 2023
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 (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
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