Rat Lake
Aitkin County, Minnesota431 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Rat Lake. Here is what has been measured.
- 21 ft max depth
- Public access
- Limited data
Rat Lake in Aitkin County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 5.5 ft visibility. Maximum depth: 21 ft. Surface area: 431.3 acres.
Minnesota DNR's Targeted Survey on July 8, 2022 caught 6.92 largemouth bass per hour of electrofishing at Rat Lake. Length samples in the latest survey that recorded them ran 10–15 inches. DNR survey details →
Rat Lake is a 431-acre lake in Aitkin County, Minnesota with a maximum depth of 21 feet. Overall water quality is improving over recent sampling years. The lake supports 13 documented fish species including black bullhead, black crappie, and bluegill. Public access is available.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-11. Methodology: how these readings are compared.
Rat Lake covers about 430 acres in Aitkin County. The median ice-out date is April 12, which is when the open-water season begins. Vrbo is where to look for cabins and lake homes around Rat Lake, and Booking.com and Expedia search hotels near the lake for your dates.
What Rat Lake is good for
From access and monitoring records, not editorial picks.
- Fishing13 species recorded
- Ice seasonIce-out around Apr 12
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Rat 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 Rat Lake
These are the measurements Minnesota PCA publishes for Rat 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 5.5 ft. TSI 53.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 5.5ft | 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. | 53 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Rat Lake
Answers come straight from the public measurements and survey records on this page.
Minnesota DNR's Targeted Survey on July 8, 2022 caught 6.92 largemouth bass per hour of electrofishing at Rat Lake. Length samples in the latest survey that recorded them ran 10–15 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Rat Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. 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: 2022-07-08 (Targeted Survey).
11 surveys on file · most recent 2022-07-08 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Golden Shiner | 22.65 | ||
| Bluegill | 14.07 | 3–9 in 2022-06-21 | 0.29 lb |
| Yellow Perch | 8.27 | 4–11 in 2022-06-21 | 0.18 lb |
| Largemouth Bass | 6.83 | 10–15 in 2022-06-21 | 1.55 lb |
| Northern Pike | 3.28 | 14–30 in 2022-06-21 | 1.57 lb |
| Black Crappie | 3.03 | 4–12 in 2022-06-21 | 0.35 lb |
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.
Bluegill
Yellow Perch
Largemouth Bass
Northern Pike
From the 2022-07-08 survey
A targeted survey of nearshore fish species in Rat Lake was conducted on July 8, 2022 by Aitkin Area Fisheries Staff. Sampling sites were evenly spaced around the lake and each was sampled by backpack electrofishing and seining with a 50-foot or 15-foot seine, where possible. Backpack electrofishing was completed at…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Rat Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — RatFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Rat (0142)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — RatFish Stocking History · MN DNR LakeFinder
Lake Details
Max depth
21 ft
Surface area
431 acres
Shoreline
4.7 mi
Littoral zone
90%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
5 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,204 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Stays via Stay22
Stays near Rat Lake
Compare lakeside cabins, hotels, and vacation rentals near Rat 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 Rat Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Fish Species
Click a species to see every lake where it is documented.
Fishing Rat Lake
Water Quality Trend: Improving
Based on 6 years of monitoring (2020–2025).
Water clarity
Improving6 years
Ice season
Typical ice-out
Apr 12
Earliest Mar 21, 2012 · Latest Apr 29, 2022
Typical ice-in
Nov 23
Earliest Nov 18, 2002 · Latest Nov 27, 2012
Most recent ice-out
Apr 29
2022
8 observations · Minnesota PCA ice records
Nearby Lakes in Aitkin County
Frequently asked questions about Rat Lake
Where is Rat Lake?
- Rat 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 Rat Lake?
- Rat Lake in Aitkin County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 5.5 ft visibility. Maximum depth: 21 ft. Surface area: 431.3 acres.
Is Rat Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Rat Lake?
- Rat Lake has a maximum depth of 21 feet. The lake covers 431.3 acres.
What fish are in Rat Lake?
- Fish species found in Rat Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, white sucker, yellow bullhead, yellow perch. Rat Lake is located in Aitkin County, Minnesota.
What did the DNR fisheries survey find at Rat Lake?
- Minnesota DNR's Targeted Survey on July 8, 2022 caught 6.92 largemouth bass per hour of electrofishing at Rat Lake. Length samples in the latest survey that recorded them ran 10–15 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Rat Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
When does Rat Lake thaw?
- Rat Lake typically has ice-out around Apr 12. Ice typically forms around Nov 23. The open water season is approximately 225 days.
Can I fish at Rat Lake?
- Public access to Rat Lake is listed as yes on the lake record. 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 Rat Lake across LakeQuality
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Where this data comes from
35 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
MNPCA35 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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Ice data from Minnesota DNR Climate