Third Lake
Third Lake in Chisago County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5.5 ft visibility.
- Clarity
- 5.5 ft
- Typical in August
- 75°F
- Mean depth
- ~8 ft est.
- Trend
- ↑ Improving
- Public access
- No
Next lake in Chisago County
Why Third Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Third Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by MPCA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Third Lake is a lake in Chisago County, Minnesota with an estimated average depth of about 8 feet. Overall water quality is improving over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2020-09-05. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Third Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Murky, only visible to about 5.5 ft. Trophic State Index: 53.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.5 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 53 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Third Lake
Compare lakeside cabins, hotels, and vacation rentals near Third Lake in Chisago 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 Third Lake
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Water Temperature
Third Lake typically sits around 75°F at the surface in August. Summer average is about 74°F. Usually warmest in Jul (about 76°F) and coldest in Oct (about 47°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 46 field readings (2019–2019) via the EPA Water Quality Portal. See the full Third Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~8 ft est. |
| Public Access | No |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Minnesota has not published bathymetry for Third Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Third Lake
Water Quality Trend: ↑ Improving
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.07 m/yr | 3 |
| Phosphorus | ↑ Improving | -22 µg/L/yr | 2 |
| Chlorophyll-a | ↑ Improving | -9.93 µg/L/yr | 2 |
EPA Impairment Status
Third Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN13-0023-00 · Official waterbody report · Matched by proximity (1.01 km)
Graded lakes near Third Lake
Third Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Chisago County
Frequently asked questions about Third Lake
What is the water quality grade for Third Lake?
- Third Lake in Chisago County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5.5 ft visibility.
Is Third Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Third Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
What is the water temperature of Third Lake?
- Third Lake typically sits around 75°F at the surface in August, from 46 EPA Water Quality Portal field readings (2019–2019). That is a typical value for the month, not a live reading.
How deep is Third Lake?
- No published bathymetric survey covers Third Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 8 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
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Where this data comes from
4 measurements from 1 monitoring station, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA4 samples · 2020
Analytical methods
- Field measurement/observation, generic method
Monitoring station identifiers (1)
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