Larson Lake
Larson Lake in Itasca County, Minnesota has a water quality grade of B (Good). Water clarity: 21 ft visibility. Phosphorus: 4 µg/L. Chlorophyll-a (algae): 1.5 µg/L. Maximum depth: 177 ft. Surface area: 208.18 acres.
- Clarity
- 21 ft
- Typical in August
- 48°F
- Max depth
- 177 ft
- Area
- 208 acres
- Type
- Oligotrophic
- Public access
- Yes
Next lake in Itasca County
Larson Lake is a 208-acre cold, clear oligotrophic lake in Itasca County, Minnesota with a maximum depth of 177 feet. Water quality is graded B based on 1 sampling years through 2021. The lake supports 6 documented fish species including black bullhead, northern pike, and pumpkinseed. Public access is available with 1 public boat landing. Compared to the 71 other monitored lakes in Itasca County, Larson Lake ranks #49 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2021-09-14. Grade methodology: LakeGrade methodology.
Watch Larson Lake water quality
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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.
Good for swimming, clear water with low algae levels
Water Quality Grade: B (Good)
Crystal clear, you can see 21 ft down. Phosphorus level: 4 µg/L. Chlorophyll-a: 1.5 µg/L. Trophic State Index: 31.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 21 ft | Not graded |
| Phosphorus | 4 µg/L | Good |
| Chlorophyll-a (Algae) | 1.5 µg/L | Not graded |
| Trophic State Index (TSI) | 31 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Larson Lake
Compare lakeside cabins, hotels, and vacation rentals near Larson Lake in Itasca County, Minnesota — 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.
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Water Temperature
Larson Lake typically sits around 48°F at the surface in August. Summer average is about 48°F. Usually warmest in Jul (about 48°F) and coldest in May (about 44°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 159 field readings (2021–2021) via the EPA Water Quality Portal. See the full Larson Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 177 ft |
| Surface Area | 208 acres |
| Shoreline Length | 3.8 mi |
| Littoral Zone | 25% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Larson LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Larson Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Source: USGS Nonindigenous Aquatic Species (NAS) Database. Hover a chip to see scientific name, ecological context, status, and first-observed year.
DNR Fisheries Survey Summary
12 surveys on file from MN DNR Fisheries. Most recent: 2020-08-10 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Yellow Perch | 13.42 | 0.12 lb |
| TPM | 7.54 | 0.02 lb |
| Pumpkinseed | 7.30 | 0.08 lb |
| Black Bullhead | 3.58 | 0.12 lb |
| SUN | 2.00 | — |
| SPT | 1.83 | 1.92 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
Length Distributions
Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.
Yellow Perch
Pumpkinseed
Black Bullhead
SPT
From the 2020-08-10 survey
Larson Lake is located 12 miles east of Effie, MN in the Big Fork River watershed. The lake has a surface area of 198 acres and a maximum depth of 177 feet. There is a DNR-administered access at the State Campground on the west side of the lake. The current lake management plan lists Splake as the primary species of…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Larson Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — LarsonFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Larson (0648)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — LarsonFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — LarsonPublic Water Access Sites · MN DNR LakeFinder
EPA Impairment Status
Larson Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN31-0316-00 · Official waterbody report · Matched by proximity (2.72 km)
County Ranking
Ranked #49 of 72 lakes in Itasca County
Nearby Lakes With Higher Grades
Larson Lake holds Grade B. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Itasca County
Frequently asked questions about Larson Lake
What is the water quality grade for Larson Lake?
- Larson Lake in Itasca County, Minnesota has a water quality grade of B (Good). Water clarity: 21 ft visibility. Phosphorus: 4 µg/L. Chlorophyll-a (algae): 1.5 µg/L. Maximum depth: 177 ft. Surface area: 208.18 acres.
Is Larson Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Larson Lake has a water quality grade of B (Good). Algae concentration (chlorophyll-a) is 1.5 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Larson Lake?
- Larson Lake typically sits around 48°F at the surface in August, from 159 EPA Water Quality Portal field readings (2021–2021). That is a typical value for the month, not a live reading.
How deep is Larson Lake?
- Larson Lake has a maximum depth of 177 feet. The lake covers 208.18 acres.
What fish are in Larson Lake?
- Fish species found in Larson Lake include black bullhead, northern pike, pumpkinseed, splake, white sucker, yellow perch. Larson Lake is located in Itasca County, Minnesota.
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 LakeGrade
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Where this data comes from
13 measurements from 1 monitoring station, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA13 samples · 2021
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent 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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory