Second Lake
Carlton County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Second Lake. Here is what has been measured.
- Eutrophic
- Public access
- Limited data
Second Lake in Carlton County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 1.2 ft visibility. Phosphorus: 75 µg/L. Chlorophyll-a (algae): 13 µg/L.
Second Lake is a productive, nutrient-rich eutrophic lake in Carlton County, Minnesota. Water clarity is improving over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 21 other monitored lakes in Carlton County, Second Lake ranks #21 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-07-01. 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 Second 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 Second Lake
These are the measurements Minnesota PCA publishes for Second Lake, 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 1.2 ft of visibility. Phosphorus 75 µg/L. Chlorophyll-a 13 µg/L. TSI 65.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 75µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 13µg/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. | 65 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Second Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Second Lake typically sits around 67°F at the surface in August. Summer average is about 67°F. Usually warmest in Jul (about 71°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 (71°F).
Typical surface water temperature by month, from 19 field readings (2010–2021) via the EPA Water Quality Portal. See the full Second Lake water temperature breakdown →
Stays via Stay22
Stays near Second Lake
Compare lakeside cabins, hotels, and vacation rentals near Second Lake in Carlton 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. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Second Lake are listed below.
Top-rated places to stay near Second Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
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Fishing Second Lake
Water Quality Trend: Stable
Based on 5 years of monitoring (2020–2024).
Water clarity
Improving5 years
Phosphorus
Worsening+20.9 µg/L/yr4 years
Chlorophyll-a
Stable0 µg/L/yr5 years
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Second Lake under Clean Water Act (NPDES) discharge permits.
- Jarden Home BrandsCloquet · 2.5 mi away · NPDES MN0000337
- Sappi Cloquet LlcCloquet · 3.3 mi away · NPDES MN0001431
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 Carlton County
Frequently asked questions about Second Lake
Where is Second Lake?
- Second Lake is a lake in Carlton County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Second Lake?
- Second Lake in Carlton County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 1.2 ft visibility. Phosphorus: 75 µg/L. Chlorophyll-a (algae): 13 µg/L.
Is Second Lake 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 Second Lake?
- Second Lake typically sits around 67°F at the surface in August, from 19 EPA Water Quality Portal field readings (2010–2021). That is a typical value for the month, not a live reading.
Can I fish at Second Lake?
- Public access to Second 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 Second Lake across LakeQuality
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Fish species and best lakes in Carlton County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its readings
Lakes in the Lake Superior Basin (MN+WI), ranked by water quality
Minnesota's cleanest lakes, ranked on agency measurements
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State Parks Near Second Lake
Other Lakes in Minnesota
Eutrophic Lakes in Minnesota
Where this data comes from
60 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Fond du Lac Band of Chippewa (MN)
FONDULAC_WQX60 samples · 2020–2024
Analytical methods
- Phosphorus by Two Reagent Colorimetry
- Phosphorus by Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
- 10200 H ~ Chlorophyll a-b-c Determination
- Color, APHA Platinum-Cobalt
- For determination of Copper by the Bicinchoninate 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
Regulated discharger data from EPA ECHO (ICIS-NPDES)