Sea Gull Lake
Sea Gull Lake in Cook County, Minnesota has a water quality grade of A (Excellent). Water clarity: 14.3 ft visibility. Phosphorus: 7 µg/L. Chlorophyll-a (algae): 2.7 µg/L. Maximum depth: 40 ft. Surface area: 167.88 acres.
- Clarity
- 14.3 ft
- Max depth
- 40 ft
- Area
- 168 acres
- Type
- Oligotrophic
- Public access
- Yes
Next lake in Cook County
Sea Gull Lake is a 168-acre cold, clear oligotrophic lake in Cook County, Minnesota with a maximum depth of 40 feet. Water quality is graded A based on 2 sampling years through 2025. The lake supports 12 documented fish species including black crappie, bluegill, and burbot. Public access is available. Compared to the 43 other monitored lakes in Cook County, Sea Gull Lake ranks #17 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-15. 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)
Good clarity, visible to about 14.3 ft. Phosphorus level: 7 µg/L. Chlorophyll-a: 2.7 µg/L. Trophic State Index: 37.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 14.3 ft | Not graded |
| Phosphorus | 7 µg/L | Good |
| Chlorophyll-a (Algae) | 2.7 µg/L | Good |
| Trophic State Index (TSI) | 37 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Sea Gull Lake
Compare lakeside cabins, hotels, and vacation rentals near Sea Gull Lake in Cook 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 | 40 ft |
| Surface Area | 168 acres |
| Shoreline Length | 7.2 mi |
| Littoral Zone | 65% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Sea Gull Lake
DNR Fisheries Survey Summary
5 surveys on file from MN DNR Fisheries. Most recent: 2017-08-14 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| BNS | 5.44 | — |
| CIS | 3.67 | 0.52 lb |
| Smallmouth Bass | 2.55 | 1.19 lb |
| LKW | 2.48 | 2.08 lb |
| Tullibee (Cisco) | 1.94 | 1.07 lb |
| Walleye | 1.49 | 0.93 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.
CIS
Smallmouth Bass
LKW
Tullibee (Cisco)
From the 2017-08-14 survey
Gull Lake lies on the Sea Gull River between Sea Gull Lake (upstream) and Saganaga Lake (downstream), and was last surveyed in 1998. Movement of fish between Saganaga and Gull Lakes occurs regularly, while a barrier falls blocks movement of fish (and other organisms) from Gull Lake to Sea Gull Lake. This standard…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Sea Gull Lake. 2 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — GullFisheries Lake Survey · MN DNR LakeFinder
- —Public Water Access Sites — GullPublic Water Access Sites · MN DNR LakeFinder
EPA Impairment Status
Sea Gull 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 MN16-0629-00 · Official waterbody report
County Ranking
Ranked #17 of 44 lakes in Cook County
Nearby Lakes in Cook County
Frequently asked questions about Sea Gull Lake
What is the water quality grade for Sea Gull Lake?
- Sea Gull Lake in Cook County, Minnesota has a water quality grade of A (Excellent). Water clarity: 14.3 ft visibility. Phosphorus: 7 µg/L. Chlorophyll-a (algae): 2.7 µg/L. Maximum depth: 40 ft. Surface area: 167.88 acres.
Is Sea Gull Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Sea Gull Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 2.7 µg/L. Always check local health department advisories before swimming.
How deep is Sea Gull Lake?
- Sea Gull Lake has a maximum depth of 40 feet. The lake covers 167.88 acres.
What fish are in Sea Gull Lake?
- Fish species found in Sea Gull Lake include black crappie, bluegill, burbot, cisco species, green sunfish, lake whitefish, northern pike, pumpkinseed, smallmouth bass, walleye, white sucker, yellow perch. Sea Gull Lake is located in Cook County, Minnesota.
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Where this data comes from
129 measurements from 6 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
MNPCA129 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 (6)
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