Turtle Lake
Turtle Lake in Itasca County, Minnesota has a water quality grade of A (Excellent). Water clarity: 17.1 ft visibility. Phosphorus: 8 µg/L. Chlorophyll-a (algae): 2.1 µg/L. Maximum depth: 54 ft. Surface area: 119.55 acres.
- Clarity
- 17.1 ft
- Max depth
- 54 ft
- Area
- 120 acres
- Type
- Oligotrophic
- Trend
- → Stable
- Public access
- No
Next lake in Itasca County
Turtle Lake is a 120-acre cold, clear oligotrophic lake in Itasca County, Minnesota with a maximum depth of 54 feet. Water quality is graded A based on 2 sampling years through 2025. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 71 other monitored lakes in Itasca County, Turtle Lake ranks #13 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-16. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Crystal clear, you can see 17.1 ft down. Phosphorus level: 8 µg/L. Chlorophyll-a: 2.1 µg/L. Trophic State Index: 36.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 17.1 ft | Not graded |
| Phosphorus | 8 µg/L | Good |
| Chlorophyll-a (Algae) | 2.1 µg/L | Good |
| Trophic State Index (TSI) | 36 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Turtle Lake
Compare lakeside cabins, hotels, and vacation rentals near Turtle 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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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 54 ft |
| Surface Area | 120 acres |
| Shoreline Length | 3.2 mi |
| Littoral Zone | 82% |
| Public Access | No |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fishing Turtle Lake
DNR Fisheries Survey Summary
2 surveys on file from MN DNR Fisheries. Most recent: 1989-07-17 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 9.63 | 0.35 lb |
| Northern Pike | 5.27 | 1.57 lb |
| Pumpkinseed | 2.75 | 0.35 lb |
| Yellow Perch | 1.96 | 0.17 lb |
| Black Crappie | 1.88 | 0.53 lb |
| Walleye | 0.86 | 1.97 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
From the 1989-07-17 survey
WALLEYES, ALTHOUGH NEVER STOCKED IN GRASS LAKE, HAVE BEEN SAMPLED IN BOTH THE 1978 SURVEY AND THIS ASSESSMENT. YOUNG-OF-THE-YEAR LARGEMOUTH BASS WERE CAPTURED IN THE MINNOW TRAPS BUT NONE WERE CAUGHT IN THE NETS. NORTHERN PIKE ABUNDANCE, AS INDICATED BY GILLNET CATCH, IS WELL ABOVE STATE AND LOCAL MEDIANS.
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Turtle Lake. 2 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — GrassFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Grass (0708)Aquatic Plant Report · MN DNR LakeFinder
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.006 m/yr | 6 |
| Phosphorus | → Stable | -0.07 µg/L/yr | 6 |
| Chlorophyll-a | → Stable | +0.02 µg/L/yr | 6 |
EPA Impairment Status
Turtle 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 MN31-0725-00 · Official waterbody report
County Ranking
Ranked #13 of 72 lakes in Itasca County
Nearby Lakes in Itasca County
Frequently asked questions about Turtle Lake
What is the water quality grade for Turtle Lake?
- Turtle Lake in Itasca County, Minnesota has a water quality grade of A (Excellent). Water clarity: 17.1 ft visibility. Phosphorus: 8 µg/L. Chlorophyll-a (algae): 2.1 µg/L. Maximum depth: 54 ft. Surface area: 119.55 acres.
Is Turtle Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Turtle Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 2.1 µg/L. Always check local health department advisories before swimming.
How deep is Turtle Lake?
- Turtle Lake has a maximum depth of 54 feet. The lake covers 119.55 acres.
Explore Turtle Lake across LakeGrade
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Where this data comes from
125 measurements from 2 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA125 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (2)
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