First Sister Lake is a productive, nutrient-rich eutrophic lake in Washtenaw County, Michigan. Water quality is graded F based on 1 sampling years through 2022. The lake supports 3 documented fish species including Bluegill, Green sunfish, and Yellow bullhead. Compared to the 16 other monitored lakes in Washtenaw County, First Sister Lake ranks #15 for water quality.
Source: EPA Water Quality Portal sampling records, Michigan DNR, last sampled 2022-03-20. 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 3 ft of visibility. Trophic State Index: 61.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 61 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near First Sister Lake
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Fish Species
Click a species to see every graded lake where it is documented.
Fishing First Sister Lake
Location
County Ranking
Ranked #15 of 17 lakes in Washtenaw County
Cleaner Lakes Within 30 Miles
First Sister Lake holds Grade F. One nearby lake has a higher grade.
Nearby Lakes in Washtenaw County
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High nutrients, frequent algae, reduced clarity
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More records, surveys & data sources
EPA Impairment Status
First Sister 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 MI040900050308-02 · Official waterbody report · Matched by proximity (0.52 km)
Regulated Pollution Sources Nearby
15 EPA-permitted facilities operate within about 5 miles of First Sister Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 7 facilities have a reported Clean Water Act violation in the past three years.
- Ann Arbor MS4Ann Arbor · 3 mi away · NPDES MI0053856Major
- Federal Mogul Corp-Tech CenterAnn Arbor · 1.3 mi away · NPDES MI0002089Recent violation
- Ntn Technical CenterAnn Arbor · 2.2 mi away · NPDES MI0041939Recent violation
- Eaton Corporation-Ann ArborAnn Arbor · 2.2 mi away · NPDES MI0004618Recent violation
- Mdot-Ann Arbor MS4Ann Arbor · 3 mi away · NPDES MI0053911Recent violation
- Sweepster Attachments LlcDexter · 3.5 mi away · NPDES MI0045934Recent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2022-03-20
Monitoring stations: 1