Saint Johns Lake
Kandiyohi County, MinnesotaHypereutrophic
Saint Johns Lake grades an F: every scored parameter (clarity and phosphorus) rates poorly, placing it among the most stressed lakes monitored in Minnesota. clarity and phosphorus rate similarly, so there is no obvious single lever to pull on watershed management.
Hypereutrophic conditions mean the lake is operating at the upper end of the productivity scale, with all the bloom risk that implies. 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. Within Kandiyohi County's 35 graded lakes, Saint Johns Lake ranks 25 — below the local median, though not at the bottom.
No invasive species are currently listed at Saint Johns Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Saint Johns Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. No formal public access is documented at Saint Johns Lake — most use is by shoreline residents and their guests. The lake has a partial ice record — 8 observed ice-outs, centered near Apr 7. 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 2023-09-12. Grade methodology: LakeGrade methodology.
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 0.5 ft of visibility. Phosphorus level: 188 µg/L. Trophic State Index: 83.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.5 ft | F |
| Phosphorus | 188 µg/L | F |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 83 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.019 m/yr | 4 |
Ice Season
Historical ice data from Minnesota DNR (11 observations).
Estimated open water season: 227 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2021-03-21 (2021) | 2013-04-30 (2013) |
| Ice-In | 2006-11-17 (2006) | 2007-11-22 (2007) |
Most recent ice-out: 2022-04-12
Location
County Ranking
Ranked #25 of 35 lakes in Kandiyohi County
Cleaner Lakes Within 30 Miles
Saint Johns Lake holds Grade F. 5 nearby lakes hold higher grades.
- AHenderson LakeKandiyohi County · mi · Two grade letters higher (F → A)
- BFlorida LakeKandiyohi County · mi · Two grade letters higher (F → B)
- CEagle LakeKandiyohi County · mi · Two grade letters higher (F → C)
- DEast Solomon LakeKandiyohi County · mi · Higher grade (F → D)
- DFoot LakeKandiyohi County · mi · Higher grade (F → D)
Nearby Lakes in Kandiyohi County
More Minnesota Lake Rankings
State Parks Near Saint Johns Lake
Other Grade F Lakes in Minnesota
EPA Impairment Status
Saint Johns 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 MN34-0283-00 · Official waterbody report
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
Ice data from Minnesota DNR Climate
Most recent sample: 2023-09-12
Monitoring stations: 1