Hammal Lake
Aitkin County, Minnesota376 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Hammal Lake. Here is what has been measured.
- Impaired · Mercury
- 44 ft max depth
- Public access
- Limited data
Hammal Lake in Aitkin County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 12.5 ft visibility. Maximum depth: 44 ft. Surface area: 375.52 acres.
Minnesota DNR's Standard Survey on August 15, 2022 caught 4.17 northern pike per gill net at Hammal Lake. DNR survey details →
Hammal Lake is a 376-acre lake in Aitkin County, Minnesota with a maximum depth of 44 feet (11-foot average). Overall water quality is declining over recent sampling years. The lake supports 14 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-03. Methodology: how these readings are compared.
What Hammal Lake is good for
From access and monitoring records, not editorial picks.
- Clear water12.5 ft of visibility
- Boat launch1 documented ramp
- Fishing14 species recorded
- Ice seasonIce-out around Apr 13
- Deep water44 ft surveyed max depth
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Hammal Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Hammal Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Hammal Lake
These are the measurements Minnesota PCA publishes for Hammal Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 12.5 ft. TSI 41.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 12.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading 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. | 41 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Hammal Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Hammal Lake typically sits around 61°F at the surface in September. Summer average is about 64°F. Usually warmest in Jul (about 66°F) and coldest in May (about 56°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (56°F) to its warmest (66°F).
Typical surface water temperature by month, from 48 field readings (2016–2025) via the EPA Water Quality Portal. See the full Hammal Lake water temperature breakdown →
Minnesota DNR's Standard Survey on August 15, 2022 caught 4.17 northern pike per gill net at Hammal Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Hammal Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
11 surveys on file from MN DNR Fisheries. Most recent: 2022-08-15 (Standard Survey).
11 surveys on file · most recent 2022-08-15 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Yellow Bullhead | 21.78 | 5–12 in 2022-08-15 | 0.49 lb |
| Bluegill | 19.86 | 3–8 in 2022-08-15 | 0.17 lb |
| Golden Shiner | 11.87 | ||
| Largemouth Bass | 11.07 | 6–18 in 2022-08-15 | 1.19 lb |
| Bluntnose Minnow | 10.55 |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and is not a weekly bite report.
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 Bullhead
Bluegill
Largemouth Bass
From the 2022-08-15 survey
Hammal Lake is a moderate sized lake located a few miles southwest of the City of Aitkin. The lake has diverse habitat including shallow vegetated bays, submerged points, and deep holes. Residential development ranging from seasonal cabins to year-round homes occurs around much of the shoreline. There is a public…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Hammal Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — HammalFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Hammal (0048)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — HammalPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
44 ft
Average depth
10.5 ft
Surface area
376 acres
Shoreline
4.6 mi
Littoral zone
70%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
83 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,224 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Hammal 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 Hammal Lake
Compare lakeside cabins, hotels, and vacation rentals near Hammal Lake in Aitkin 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.
Top-rated places to stay near Hammal Lake
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Follow Hammal Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Hammal Lake
Water Quality Trend: Worsening
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening6 years
Ice season
Typical ice-out
Apr 13
Earliest Mar 30, 2017 · Latest May 4, 2022
Typical ice-in
Nov 27
Earliest Nov 8, 2019 · Latest Dec 14, 2004
Most recent ice-out
Apr 2
2024
24 observations · Minnesota PCA ice records
EPA Impairment Status
Hammal Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN01-0161-00 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Hammal Lake under Clean Water Act (NPDES) discharge permits.
- Aitkin WwtpAitkin · 4.5 mi away · NPDES MN0020095
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 Aitkin County
Frequently asked questions about Hammal Lake
Where is Hammal Lake?
- Hammal Lake is a lake in Aitkin County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Hammal Lake?
- Hammal Lake in Aitkin County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 12.5 ft visibility. Maximum depth: 44 ft. Surface area: 375.52 acres.
Is Hammal Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Hammal Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
What is the water temperature of Hammal Lake?
- Hammal Lake typically sits around 61°F at the surface in September, from 48 EPA Water Quality Portal field readings (2016–2025). That is a typical value for the month, not a live reading.
How deep is Hammal Lake?
- Hammal Lake has a maximum depth of 44 feet and an average depth of 10.5 feet. The lake covers 375.52 acres.
What fish are in Hammal Lake?
- Fish species found in Hammal Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, walleye, yellow bullhead, yellow perch. Hammal Lake is located in Aitkin County, Minnesota.
What did the DNR fisheries survey find at Hammal Lake?
- Minnesota DNR's Standard Survey on August 15, 2022 caught 4.17 northern pike per gill net at Hammal Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Hammal Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
When does Hammal Lake thaw?
- Hammal Lake typically has ice-out around Apr 13. Ice typically forms around Nov 27. The open water season is approximately 228 days.
Are there boat ramps on Hammal Lake?
- Hammal Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Hammal Lake. Public access is listed as yes.
Can I fish at Hammal Lake?
- Hammal 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 Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Hammal Lake across LakeQuality
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Where this data comes from
25 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA25 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
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)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate