Black Lake
Ramsey County, MinnesotaEutrophic
The LakeGrade rubric puts Black Lake at a C: clarity at 6.9 ft, 36 µg/L of phosphorus, and a TSI of 53 signal an intermediate trophic state. The two scored sub-grades — clarity and phosphorus — track close together, so neither one is dragging the average down.
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. Among the 49 graded lakes in Ramsey County, Black Lake sits at rank 19, above the county median.
No invasive species are currently listed at Black Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Black Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. No formal public access is documented at Black Lake — most use is by shoreline residents and their guests. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2023-07-11. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Moderate clarity, visible to about 6.9 ft. Phosphorus level: 36 µg/L. Trophic State Index: 53.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.9 ft | C |
| Phosphorus | 36 µg/L | C |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 53 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Quality Trend: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.254 m/yr | 5 |
| Phosphorus | ↓ Declining | +6.05 µg/L/yr | 5 |
Location
County Ranking
Ranked #19 of 49 lakes in Ramsey County
Cleaner Lakes Within 30 Miles
Black Lake holds Grade C. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Ramsey County
More Minnesota Lake Rankings
State Parks Near Black Lake
Other Grade C Lakes in Minnesota
Eutrophic Lakes in Minnesota
EPA Impairment Status
Black 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 MN62-0027-00 · Official waterbody report · Matched by proximity (1.63 km)
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Grading methodology based on Metropolitan Council standards
Most recent sample: 2023-07-11
Monitoring stations: 1