North Long Lake
North Long Lake in Ramsey County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 2.5 ft visibility. Phosphorus: 102 µg/L. Chlorophyll-a (algae): 30.9 µg/L.
- Clarity
- 2.5 ft
- Typical in August
- 73°F
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- Yes
Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near North Long Lake →
Next lake in Ramsey County
North Long Lake is a productive, nutrient-rich eutrophic lake in Ramsey County, Minnesota. Water quality is graded F based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 43 other monitored lakes in Ramsey County, North Long Lake ranks #39 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-15. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyAlgae risk
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.
Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom
Water Quality Grade: F (Algae-prone)
Very murky, less than 2.5 ft of visibility. Phosphorus level: 102 µg/L. Chlorophyll-a: 30.9 µg/L. Trophic State Index: 66.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.5 ft | Not graded |
| Phosphorus | 102 µg/L | Poor |
| Chlorophyll-a (Algae) | 30.9 µg/L | Poor |
| Trophic State Index (TSI) | 66 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near North Long Lake
Compare lakeside cabins, hotels, and vacation rentals near North Long Lake in Ramsey 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 grade measures nutrients and algae, not lodging — cabins and rentals around North Long Lake are listed below.
Top-rated places to stay near North Long Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
North Long Lake typically sits around 73°F at the surface in August. Summer average is about 72°F. Usually warmest in Jul (about 75°F) and coldest in Mar (about 39°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 443 field readings (2010–2025) via the EPA Water Quality Portal. See the full North Long Lake water temperature breakdown →
Fishing North Long Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for North Long Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Public Water Access Sites — North LongPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.071 m/yr | 6 |
| Phosphorus | ↑ Improving | -1.7 µg/L/yr | 6 |
| Chlorophyll-a | ↑ Improving | -0.95 µg/L/yr | 6 |
EPA Impairment Status
North Long 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 MN62-0067-01 · Official waterbody report
County Ranking
Ranked #39 of 44 lakes in Ramsey County
Nearby Lakes With Higher Grades
North Long Lake holds Grade F. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Ramsey County
Frequently asked questions about North Long Lake
What is the water quality grade for North Long Lake?
- North Long Lake in Ramsey County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 2.5 ft visibility. Phosphorus: 102 µg/L. Chlorophyll-a (algae): 30.9 µg/L.
Is North Long Lake safe to swim in?
- Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom. North Long Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 30.9 µg/L. Always check local health department advisories before swimming.
What is the water temperature of North Long Lake?
- North Long Lake typically sits around 73°F at the surface in August, from 443 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
Explore North Long Lake across LakeGrade
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Where this data comes from
323 measurements from 2 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
MNPCA323 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2130 B ~ Nephelometric Method
- Turbidity by Nephelometry
Monitoring station identifiers (2)
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)