Allegan County, Michigan · Water Quality Report Card
Longterm Lake
Longterm Lake in Allegan County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar.
- Trend
- ↓ Declining
Longterm Lake is a lake in Allegan County, Michigan. Overall water quality is declining over recent sampling years.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2024-10-23. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not rated for swimming — there is not enough monitoring data to judge this lake
Water Quality Grade: Not rated
No clarity data.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data |
Where to stay near Longterm Lake
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Fishing Longterm Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.25 m/yr | 2 |
| Phosphorus | ↓ Declining | +76 µg/L/yr | 3 |
Location
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EPA Impairment Status
Longterm 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 MI040500030803-01 · Official waterbody report · Matched by proximity (1.66 km)
Where this data comes from
15,044 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Match-e-be-nash-she-wish Band of Pottawatomi Indians of Michigan (Gun Lake)
GNLK01_WQX15,044 samples · 2020–2024
Monitoring station identifiers (1)
Grade thresholds come from the U.S. EPA National Lakes Assessment 2022 Technical Support Document (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion
Most recent sample: 2024-10-23
Monitoring stations: 1