Thread Lake
Genesee County, Michigan80 acresView mapDirections
Not Rated: one monitoring station are on record, but they measured water clarity only. LakeQuality’s A–F method grades total phosphorus, total nitrogen, chlorophyll-a, and turbidity; clarity is shown, not scored.
- Impaired · Nutrients (phosphorus, nitrogen)
- Limited data
Thread Lake in Genesee County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1.8 ft visibility. Surface area: 80 acres.
- Clarity
- 1.8 ft
- Area
- 80 acres
- Trend
- → Stable
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Watch Thread Lake’s letter
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Why Thread Lake has no grade
Thread Lake has monitoring on record from one station, but only water clarity was measured. LakeQuality’s A–F letter uses total phosphorus, total nitrogen, chlorophyll-a, and turbidity against EPA National Lakes Assessment condition classes. With none of those grading measurements on record, Thread Lake is Not Rated — not an F. Its 1.8-foot median from 17 readings collected 2021–2022 is still shown as clarity, but clarity alone cannot earn a letter.
Not Rated is EPA Integrated Reporting Category 3 — insufficient information. Everything below that has been measured is still reported on this page.
Sampling is run by EGLE and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Thread Lake is a 80-acre lake in Genesee County, Michigan. Water clarity is improving over recent sampling years.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2022-09-17. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Thread Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), pCBs. Check local advisories before you swim.
Water quality measurements for Thread Lake
These readings exist but are not enough for an A–F grade — see why.
Very murky, less than 1.8 ft of visibility. TSI 69.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.8 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 69 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 80 acres |
No bathymetric survey has been published for Thread Lake, so its depth is not documented here.
Fishing Thread Lake
Water Quality Trend: → Stable
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.44 m/yr | 2 |
| Phosphorus | ↓ Declining | +7 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Thread Lake is a man-made reservoir impounded by the Thread Lake Dam (completed 1973), built primarily for recreation on the Thread Creek; gravity-type dam, 9 ft tall and 293 ft long.
- Surface area
- 80 ac
- Normal storage
- 320 ac-ft
- Max storage
- 1,250 ac-ft
- Drainage area
- 57.9 sq mi
- Hazard class
- Significant
- Owner
- City of Flint
Source: USACE National Inventory of Dams, NID ID MI00063 · Operator website
EPA Impairment Status
Thread Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MI040802040306-03 · Official waterbody report
Regulated Pollution Sources Nearby
9 EPA-permitted facilities operate within about 5 miles of Thread Lake under Clean Water Act (NPDES) discharge permits. 7 facilities have a reported Clean Water Act violation in the past three years.
- Bendle Ps MS4-GeneseeBurton · 1.5 mi away · NPDES MI0060346Recent violation
- Burton MS4-GeneseeBurton · 2.9 mi away · NPDES MI0060093Recent violation
- Atherton Ps MS4-GeneseeBurton · 3 mi away · NPDES MI0060357Recent violation
- Grand Blanc Twp MS4-GeneseeGrand Blanc · 3.3 mi away · NPDES MI0060099Recent violation
- Genesee Co MS4Flint · 4.1 mi away · NPDES MI0060015Recent violation
- Bentley Ps MS4-GeneseeBurton · 4.2 mi away · NPDES MI0060350Recent 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.
Graded lakes near Thread Lake
Thread Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Genesee County
Frequently asked questions about Thread Lake
Where is Thread Lake?
- Thread Lake is a lake in Genesee County, Michigan. LakeQuality has not rated this lake (UNRATED) — the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity.
What is the water quality grade for Thread Lake?
- Thread Lake in Genesee County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1.8 ft visibility. Surface area: 80 acres.
Is Thread Lake safe to swim in?
- The letter is not a swimming clearance. Thread Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), pCBs. Check local advisories before you swim.
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Where this data comes from
17 measurements from 1 monitoring station, 2021–2022. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- North American Lake Management Society
NALMS17 samples · 2021–2022
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)