Jacksonville Lake is a 477-acre productive, nutrient-rich eutrophic lake in Morgan County, Illinois. Water quality is graded D based on 2 sampling years through 2022. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 1 other monitored lakes in Morgan County, Jacksonville Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois DNR, last sampled 2022-10-18. Grade methodology: LakeGrade methodology.
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Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Very murky, less than 1.8 ft of visibility. Phosphorus level: 48 µg/L. Trophic State Index: 64.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.8 ft | F |
| Phosphorus | 48 µg/L | C |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 64 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 477 acres |
| Public Access | Yes |
Where to stay near Jacksonville Lake
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Fishing Jacksonville Lake
Recreation & Access
Location
County Ranking
Ranked #1 of 2 lakes in Morgan County
Nearby Lakes in Morgan County
Explore Jacksonville Lake across LakeGrade
More Illinois Lake Rankings
Other Grade D Lakes in Illinois
Eutrophic Lakes in Illinois
Compare Jacksonville Lake With Nearby Lakes
More records, surveys & data sources
Reservoir Info (USACE NID)
Jacksonville Lake is a man-made reservoir impounded by the Lake Jacksonville Dam (completed 1939), built primarily for recreation on the SANDY CREEK; earth-type dam, 54 ft tall and 980 ft long.
- Surface area
- 477 ac
- Normal storage
- 6,099 ac-ft
- Max storage
- 12,812 ac-ft
- Drainage area
- 10.8 sq mi
- Hazard class
- Significant
- Owner
- CITY OF JACKSONVILLE
All listed purposes: Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID IL00711 · Operator website
EPA Impairment Status
Jacksonville Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit IL_RDI · Official waterbody report
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2022-10-18
Monitoring stations: 3