Little Mantrap Lake
Little Mantrap Lake in Hubbard County, Minnesota has a water quality grade of A (Excellent). Water clarity: 17 ft visibility. Phosphorus: 8 µg/L. Chlorophyll-a (algae): 2.5 µg/L. Maximum depth: 54 ft. Surface area: 380.95 acres.
- Clarity
- 17 ft
- Typical in August
- 65°F
- Max depth
- 54 ft
- Area
- 381 acres
- Type
- Oligotrophic
- Trend
- → Stable
- Public access
- Yes
- Ice-out
- Apr 21
- Open water
- 216 days
Next lake in Hubbard County
Little Mantrap Lake is a 381-acre cold, clear oligotrophic lake in Hubbard County, Minnesota with a maximum depth of 54 feet (14-foot average). Water quality is graded A based on 2 sampling years through 2025. The lake supports 13 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 2 public boat landings. Compared to the 67 other monitored lakes in Hubbard County, Little Mantrap Lake ranks #17 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-26. Grade methodology: LakeGrade methodology.
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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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Crystal clear, you can see 17 ft down. Phosphorus level: 8 µg/L. Chlorophyll-a: 2.5 µg/L. Trophic State Index: 37.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 17 ft | Not graded |
| Phosphorus | 8 µg/L | Good |
| Chlorophyll-a (Algae) | 2.5 µg/L | Good |
| Trophic State Index (TSI) | 37 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Little Mantrap Lake
Compare lakeside cabins, hotels, and vacation rentals near Little Mantrap Lake in Hubbard 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
Little Mantrap Lake typically sits around 65°F at the surface in August. Summer average is about 64°F. Usually warmest in Jul (about 65°F) and coldest in May (about 52°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 127 field readings (2021–2025) via the EPA Water Quality Portal. See the full Little Mantrap Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Little Mantrap Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (118,032 cells/mL) on May 23, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 54 ft |
| Average Depth | 14 ft |
| Surface Area | 381 acres |
| Shoreline Length | 9.2 mi |
| Littoral Zone | 52% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Little Mantrap LakePublic
- Hemphiil LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Little Mantrap Lake
DNR Fisheries Survey Summary
13 surveys on file from MN DNR Fisheries. Most recent: 2022-07-25 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Yellow Bass | 16.43 | 0.45 lb |
| Bluegill | 14.16 | 0.15 lb |
| CNM | 13.88 | — |
| Green Sunfish | 12.76 | 0.14 lb |
| Largemouth Bass | 8.95 | 0.78 lb |
| Bluntnose Minnow | 7.08 | — |
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 Bass
Bluegill
Green Sunfish
Largemouth Bass
From the 2022-07-25 survey
Little Mantrap Lake is located thirteen miles north of Park Rapids on the border of Becker and Hubbard County. Little Mantrap has a surface area of 381 acres and a maximum depth of 54 feet. A DNR owned public access is located on the south shore of the lake. Little Mantrap provides angling opportunities for Largemouth…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Little Mantrap Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Little MantrapFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Little Mantrap (1223)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — Little MantrapFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — Little MantrapPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.001 m/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (39 observations).
Estimated open water season: 216 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2012-03-24 (2012) | 2022-05-08 (2022) |
| Ice-In | 2003-11-08 (2003) | 1999-12-07 (1999) |
Most recent ice-out: 2024-04-06
EPA Impairment Status
Little Mantrap Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MN29-0313-00 · Official waterbody report
County Ranking
Ranked #17 of 68 lakes in Hubbard County
Nearby Lakes in Hubbard County
Frequently asked questions about Little Mantrap Lake
What is the water quality grade for Little Mantrap Lake?
- Little Mantrap Lake in Hubbard County, Minnesota has a water quality grade of A (Excellent). Water clarity: 17 ft visibility. Phosphorus: 8 µg/L. Chlorophyll-a (algae): 2.5 µg/L. Maximum depth: 54 ft. Surface area: 380.95 acres.
Is Little Mantrap Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Little Mantrap Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 2.5 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Little Mantrap Lake?
- Little Mantrap Lake typically sits around 65°F at the surface in August, from 127 EPA Water Quality Portal field readings (2021–2025). That is a typical value for the month, not a live reading.
How deep is Little Mantrap Lake?
- Little Mantrap Lake has a maximum depth of 54 feet and an average depth of 14 feet. The lake covers 380.95 acres.
What fish are in Little Mantrap Lake?
- Fish species found in Little Mantrap Lake include black bullhead, black crappie, bluegill, brown bullhead, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, walleye, yellow bullhead, yellow perch. Little Mantrap Lake is located in Hubbard County, Minnesota.
When does Little Mantrap Lake thaw?
- Little Mantrap Lake typically has ice-out around Apr 21. Ice typically forms around Nov 23. The open water season is approximately 216 days.
Does Little Mantrap Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Little Mantrap Lake (clouds, ice, or an off-season gap). The most recent reading was high (118,032 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Little Mantrap Lake?
- Little Mantrap Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Little Mantrap Lake, Hemphiil Lake. Public access is listed as yes.
Explore Little Mantrap Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Hubbard County
Species activity outlook by water temperature and season
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Where this data comes from
165 measurements from 3 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
MNPCA165 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 (3)
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
Ice data from Minnesota DNR Climate