Larson Lake
Hettinger County, North Dakota235 acresView mapDirections
ND DEQ publishes the water-quality measurements for Larson Lake. Here is what has been measured.
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- 10 ft max depth
- Public access
- Limited data
Larson Lake in Hettinger County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. Water clarity: 4.8 ft visibility. Phosphorus: 613 µg/L. Chlorophyll-a (algae): 13.1 µg/L. Surface area: 235 acres.
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. 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. Methodology: how these readings are compared.
What Larson Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
Readings onlyRecreation use not supported
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. 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.
Whether Larson 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 Larson Lake
These are the measurements ND DEQ publishes for Larson Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 4.8 ft. Phosphorus 613 µg/L. Chlorophyll-a 13.1 µg/L. TSI 69.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 613µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 13.1µg/L | Measured, not scored The green pigment in algae — a direct measure of how much algae is in the water. |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 69 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Larson Lake
Answers come straight from the public measurements and survey records on this page.
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.
Column height runs from this lake’s coldest month (48°F) to its warmest (72°F).
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
Max depth
~10 ft est.
Surface area
235 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 Larson Lake.
Lake Size & Watershed
Watershed (drainage) area
31 sq mi
HydroLAKES / HydroSHEDS
Shoreline
1.5 mi
HydroLAKES / HydroSHEDS
Elevation
2,457 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
- Larson 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 Larson Lake
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 readings cover nutrients and algae, not lodging. Cabins and rentals around Larson Lake are listed below.
Top-rated places to stay near Larson Lake
Prices for Oct 23–25, 4 adults. Change dates on the map below.
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Planning a trip? Cabins and lodging at Larson Lake → · more North Dakota lake trips
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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
Designated uses not supporting: Aquatic life, Recreation.
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.
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. Its water-quality measurements are published by ND DEQ and shown on this page as reported.
What is the water quality of Larson Lake?
- Larson Lake in Hettinger County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. 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?
- Nutrient and algae readings are 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.
Can I fish at Larson Lake?
- Larson 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 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 readings
North Dakota's cleanest lakes, ranked on agency measurements
More lakes in North Dakota
Other 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)
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