Gilfillan Lake
Ramsey County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Gilfillan Lake. Here is what has been measured.
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- 48 ft max depth
Gilfillan Lake in Ramsey County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 3 ft visibility. Phosphorus: 47 µg/L. Chlorophyll-a (algae): 28.5 µg/L.
Gilfillan Lake is a productive, nutrient-rich eutrophic lake in Ramsey County, Minnesota with an estimated average depth of about 48 feet. Water clarity is declining over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 43 other monitored lakes in Ramsey County, Gilfillan Lake ranks #33 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-24. Methodology: how these readings are compared.
For a place on the water, look through cabin and lake-house rentals near Gilfillan Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
Swimming conditions
Readings onlyRecreation use not supported
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. Gilfillan Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Gilfillan 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 Gilfillan Lake
These are the measurements Minnesota PCA publishes for Gilfillan 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 3 ft of visibility. Phosphorus 47 µg/L. Chlorophyll-a 28.5 µg/L. TSI 62.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 47µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 28.5µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 62 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Gilfillan Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Gilfillan Lake typically sits around 68°F at the surface in September. Summer average is about 76°F. Usually warmest in Jul (about 79°F) and coldest in May (about 59°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (59°F) to its warmest (79°F).
Typical surface water temperature by month, from 39 field readings (2010–2022) via the EPA Water Quality Portal. See the full Gilfillan Lake water temperature breakdown →
Lake Details
Max depth
~48 ft est.
Public access
No
Listed by Minnesota PCA
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Minnesota has not published bathymetry for Gilfillan Lake.
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Surface area
96 acres
HydroLAKES / HydroSHEDS
Shoreline
1.8 mi
HydroLAKES / HydroSHEDS
Elevation
906 ft
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.
Stays via Stay22
Stays near Gilfillan Lake
Compare lakeside cabins, hotels, and vacation rentals near Gilfillan 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 readings cover nutrients and algae, not lodging. Cabins and rentals around Gilfillan Lake are listed below.
Top-rated places to stay near Gilfillan Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Fishing Gilfillan Lake
Water Quality Trend: Stable
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening6 years
Phosphorus
Improving-1.27 µg/L/yr6 years
Chlorophyll-a
Stable+0.21 µg/L/yr6 years
EPA Impairment Status
Gilfillan Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN62-0027-00 · Official waterbody report
Nearby Lakes in Ramsey County
Frequently asked questions about Gilfillan Lake
Where is Gilfillan Lake?
- Gilfillan Lake is a lake in Ramsey County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Gilfillan Lake?
- Gilfillan Lake in Ramsey County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 3 ft visibility. Phosphorus: 47 µg/L. Chlorophyll-a (algae): 28.5 µg/L.
Is Gilfillan Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Gilfillan Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Gilfillan Lake?
- Gilfillan Lake typically sits around 68°F at the surface in September, from 39 EPA Water Quality Portal field readings (2010–2022). That is a typical value for the month, not a live reading.
How deep is Gilfillan Lake?
- No published bathymetric survey covers Gilfillan Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 48 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Can I fish at Gilfillan Lake?
- Public access to Gilfillan Lake is listed as no on the lake record, so confirm before you make the trip. 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 Gilfillan Lake across LakeQuality
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Where this data comes from
135 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA135 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 (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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder