Swamp Lake Deep
Cook County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Swamp Lake Deep. Here is what has been measured.
- Eutrophic
- Limited data
Swamp Lake Deep in Cook County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 1.7 ft visibility. Phosphorus: 27 µg/L. Chlorophyll-a (algae): 9.2 µg/L.
Swamp Lake Deep is a productive, nutrient-rich eutrophic lake in Cook County, Minnesota. Overall water quality is declining over recent sampling years. Compared to the 43 other monitored lakes in Cook County, Swamp Lake Deep ranks #43 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-10. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Swamp Lake Deep 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 Swamp Lake Deep
These are the measurements Minnesota PCA publishes for Swamp Lake Deep, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 1.7 ft of visibility. Phosphorus 27 µg/L. Chlorophyll-a 9.2 µg/L. TSI 58.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.7ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 27µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 9.2µg/L | Fair GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 58 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Swamp Lake Deep
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Swamp Lake Deep typically sits around 49°F at the surface in October. Summer average is about 67°F. Usually warmest in Aug (about 70°F) and coldest in Oct (about 49°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (49°F) to its warmest (70°F).
Typical surface water temperature by month, from 167 field readings (2010–2024) via the EPA Water Quality Portal. See the full Swamp Lake Deep water temperature breakdown →
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Stays near Swamp Lake Deep
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Fishing Swamp Lake Deep
Water quality readings over time
3 seasons of samples on record (2020–2024). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Worsening2 years
Phosphorus
Worsening+2.03 µg/L/yr3 years
Chlorophyll-a
Stable+0.1 µg/L/yr3 years
Nearby Lakes in Cook County
Frequently asked questions about Swamp Lake Deep
Where is Swamp Lake Deep?
- Swamp Lake Deep is a lake in Cook County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Swamp Lake Deep?
- Swamp Lake Deep in Cook County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 1.7 ft visibility. Phosphorus: 27 µg/L. Chlorophyll-a (algae): 9.2 µg/L.
Is Swamp Lake Deep safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Swamp Lake Deep?
- Swamp Lake Deep typically sits around 49°F at the surface in October, from 167 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
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Where this data comes from
106 measurements from 2 monitoring stations, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Grand Portage Reservation
GPC5_WQX62 samples · 2022–2024 - 21GPBCH - Grand Portage Beaches (Tribal)
21GPBCH44 samples · 2020
Analytical methods
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Turbidity by Nephelometry
Monitoring station identifiers (2)
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.