Posey Lake
Lenawee County, Michigan150 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.
- 45 ft max depth
- Limited data
Posey Lake in Lenawee County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5 ft visibility. Maximum depth: 45 ft. Surface area: 150 acres.
- Clarity
- 5 ft
- Max depth
- 45 ft
- Area
- 150 acres
- Trend
- → Stable
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Watch Posey Lake’s letter
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Why Posey Lake has no grade
Posey 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, Posey Lake is Not Rated — not an F. Its 5-foot median from 73 readings collected 2016–2022 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.
Posey Lake is a 150-acre lake in Lenawee County, Michigan with a maximum depth of 45 feet. Phosphorus level is declining over recent sampling years. The lake supports 7 documented fish species including Bluegill, Common carp, and Golden redhorse.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2022-09-16. Grade methodology: LakeQuality methodology.
What Posey Lake is good for
From access and monitoring records, not editorial picks.
- Fishing7 species recorded
- Deep water45 ft surveyed max depth
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Check local advisories before you swim.
Water quality measurements for Posey Lake
These readings exist but are not enough for an A–F grade — see why.
Murky, only visible to about 5 ft. TSI 54.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 54 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 45 ft |
| Surface Area | 150 acres |
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Posey Lake
Water Quality Trend: → Stable
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.012 m/yr | 7 |
| Phosphorus | ↓ Declining | +0.92 µg/L/yr | 7 |
| Chlorophyll-a | ↑ Improving | -4.1 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Posey Lake is a man-made reservoir impounded by the Posey Lake Level Control Structure (completed 1955), built primarily for recreation on the Posey Lake Drain; gravity-type dam, 7 ft tall and 15 ft long.
- Surface area
- 150 ac
- Normal storage
- 190 ac-ft
- Max storage
- 715 ac-ft
- Drainage area
- 0 sq mi
- Hazard class
- Low
- Owner
- Lenawee County Drain Commissioner
Source: USACE National Inventory of Dams, NID ID MI02265 · Operator website
Regulated Pollution Sources Nearby
5 EPA-permitted facilities operate within about 5 miles of Posey Lake under Clean Water Act (NPDES) discharge permits. 3 facilities have a reported Clean Water Act violation in the past three years.
- Hartland Farms-CafoClayton · 1.3 mi away · NPDES MI0057536Recent violation
- Bakerlads Farm-CafoClayton · 3.8 mi away · NPDES MI0059009Recent violation
- Hudson WwtpHudson · 4.1 mi away · NPDES MI0021377Recent violation
- Hartland Farms, IncClayton · 1.3 mi away · NPDES MIA000002
- Bakerlads FarmsClayton · 3.9 mi away · NPDES MIA000014
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 Posey Lake
Posey Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Lenawee County
Frequently asked questions about Posey Lake
Where is Posey Lake?
- Posey Lake is a lake in Lenawee 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 Posey Lake?
- Posey Lake in Lenawee County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5 ft visibility. Maximum depth: 45 ft. Surface area: 150 acres.
Is Posey Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
How deep is Posey Lake?
- Posey Lake has a maximum depth of 45 feet. The lake covers 150 acres.
What fish are in Posey Lake?
- Fish species found in Posey Lake include Bluegill, Common carp, Golden redhorse, Largemouth bass, Pumpkinseed, White sucker, Yellow bullhead. Posey Lake is located in Lenawee County, Michigan.
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Where this data comes from
73 measurements from 1 monitoring station, 2016–2022. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- North American Lake Management Society
NALMS73 samples · 2016–2022
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)