Palmyra-Modesto Lake
Macoupin County, WisconsinLimited DataEutrophic
Palmyra-Modesto Lake is a 37-acre productive, nutrient-rich eutrophic lake in Macoupin County, IL. Water quality is graded C based on 1 sampling years through 2021. Compared to the 2 other monitored lakes in Macoupin County, Palmyra-Modesto Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2021-10-13. Grade methodology: LakeGrade methodology.
Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
No clarity data. Phosphorus level: 56 µg/L. Trophic State Index: 62.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | 56 µg/L | C |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 62 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 37 acres |
Location
County Ranking
Ranked #1 of 3 lakes in Macoupin County
Nearby Lakes in Macoupin County
More Wisconsin Lake Rankings
Other Grade C Lakes in Wisconsin
Cook County · Clarity: 9 ft
Cook County · Clarity: 8.5 ft
Williamson County · Clarity: 3.2 ft
Johnson County · Clarity: 4.5 ft
Gallatin County · Clarity: 3.9 ft
Rock Island County · Clarity: 4.2 ft
Eutrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Palmyra-Modesto Lake is a man-made reservoir impounded by the Palmyra-Modesto City Lake Dam (completed 1965), built primarily for water supply on the TRIB NASSA CREEK; earth-type dam, 50 ft tall and 620 ft long.
- Surface area
- 37 ac
- Normal storage
- 565 ac-ft
- Max storage
- 967 ac-ft
- Drainage area
- 1.8 sq mi
- Hazard class
- Significant
- Owner
- PALMYRA-MODESTO WATER COMMISSION
Source: USACE National Inventory of Dams, NID ID IL00772 · Operator website · Matched by proximity (0.29 km)
EPA Impairment Status
Palmyra-Modesto 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 IL_RDZP · 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
Most recent sample: 2021-10-13
Monitoring stations: 2