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C

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.

Reviewed by LakeQuality Editorial Team · Updated

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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.

MetricValueGrade
Water Clarity (Secchi Depth)6.9 ftC
Phosphorus36 µg/LC
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)53Eutrophic

High nutrients, frequent algae, reduced clarity

Water Quality Trend: Stable

Based on 5 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Improving+0.254 m/yr5
Phosphorus Declining+6.05 µg/L/yr5
See year-by-year chart →

Location

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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

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

Nutrients (phosphorus, nitrogen)

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