Jacksonville Lake
Morgan County, Illinois477 acresView mapDirections
Illinois EPA publishes the water-quality measurements for Jacksonville Lake. Here is what has been measured.
- Hypereutrophic
- 36 ft max depth
- Public access
- Limited data
Jacksonville Lake in Morgan County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 1.8 ft visibility. Phosphorus: 60.5 µg/L. Chlorophyll-a (algae): 42.2 µg/L. Surface area: 477 acres.
Jacksonville Lake is a 477-acre highly nutrient-loaded hypereutrophic lake in Morgan County, Illinois with an estimated average depth of about 36 feet. 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 EPA, last sampled 2022-10-18. Methodology: how these readings are compared.
Jacksonville Lake covers about 480 acres in Morgan County. It has one public boat landing. Vrbo is where to look for cabins and lake homes around Jacksonville Lake, and Booking.com and Expedia search hotels near the lake for your dates.
What Jacksonville Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Jacksonville Lake is safe to swim in today is a call for the Illinois Environmental Protection Agency and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Jacksonville Lake
These are the measurements Illinois EPA publishes for Jacksonville Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 1.8 ft of visibility. Phosphorus 60.5 µg/L. Chlorophyll-a 42.2 µg/L. TSI 66.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 60.5µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 42.2µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 66 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Jacksonville Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~36 ft est.
Surface area
477 acres
Public access
Yes
Listed by Illinois EPA
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Illinois has not published bathymetry for Jacksonville Lake.
Lake Size & Watershed
Watershed (drainage) area
11 sq mi
HydroLAKES / HydroSHEDS
Shoreline
10.4 mi
HydroLAKES / HydroSHEDS
Elevation
650 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Lake JacksonvillePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Jacksonville Lake
Compare lakeside cabins, hotels, and vacation rentals near Jacksonville Lake in Morgan County, Illinois — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Jacksonville Lake are listed below.
Top-rated places to stay near Jacksonville Lake
Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip? Cabins and lodging at Jacksonville Lake → · more Illinois lake trips
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Fishing Jacksonville Lake
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
Nearby Lakes in Morgan County
Frequently asked questions about Jacksonville Lake
Where is Jacksonville Lake?
- Jacksonville Lake is a lake in Morgan County, Illinois. Its water-quality measurements are published by Illinois EPA and shown on this page as reported.
What is the water quality of Jacksonville Lake?
- Jacksonville Lake in Morgan County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 1.8 ft visibility. Phosphorus: 60.5 µg/L. Chlorophyll-a (algae): 42.2 µg/L. Surface area: 477 acres.
Is Jacksonville Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Jacksonville Lake?
- No published bathymetric survey covers Jacksonville Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 36 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 477 acres.
Are there boat ramps on Jacksonville Lake?
- Jacksonville Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Lake Jacksonville. Public access is listed as yes.
Can I fish at Jacksonville Lake?
- Jacksonville Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Illinois's fish and wildlife agency, so check its current regulations before you go.
Explore Jacksonville Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Species activity outlook by water temperature and season
Where to stay at Illinois's top lakes, each with its readings
Illinois's cleanest lakes, ranked on agency measurements
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Where this data comes from
48 measurements from 3 monitoring stations, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- illinois epa
IL_EPA_WQX48 samples · 2022
Analytical methods
- MEASURED IN FIELD
- Phosphorus by Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
Monitoring station identifiers (3)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory