Gilfillan Lake
Ramsey County, MinnesotaEutrophic
Gilfillan Lake earns a D — measurements through 2024 show persistent nutrient pressure that limits clarity through the summer. Clarity is the limiting factor — phosphorus is reasonable but suspended particles or algal cells keep water transparency below Minnesota norms.
Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Gilfillan Lake ranks 37 of 49 in Ramsey County — at the lower end of the locally monitored distribution.
No invasive species are currently listed at Gilfillan Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Gilfillan Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. No formal public access is documented at Gilfillan Lake — most use is by shoreline residents and their guests. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-25. Grade methodology: LakeGrade methodology.
Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Very murky, less than 3 ft of visibility. Phosphorus level: 48 µg/L. Trophic State Index: 61.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 ft | F |
| Phosphorus | 48 µg/L | C |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 61 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.055 m/yr | 5 |
| Phosphorus | ↑ Improving | -1.75 µg/L/yr | 5 |
Location
County Ranking
Ranked #37 of 49 lakes in Ramsey County
Nearby Lakes in Ramsey County
More Minnesota Lake Rankings
State Parks Near Gilfillan Lake
Other Grade D Lakes in Minnesota
Eutrophic Lakes in Minnesota
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-09-25
Monitoring stations: 1