Carlyle Lake
Clinton County, Illinois24,580 acresView mapDirections
Illinois EPA publishes the water-quality measurements for Carlyle Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Mercury
- 53 ft max depth
- Public access
- Limited data
Carlyle Lake in Clinton County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 1.8 ft visibility. Phosphorus: 238.5 µg/L. Chlorophyll-a (algae): 38.8 µg/L. Surface area: 24580 acres.
Carlyle Lake is a 24,580-acre highly nutrient-loaded hypereutrophic lake in Clinton County, Illinois with an estimated average depth of about 53 feet. Limited fish-species data available. Public access is available with 14 public boat landings.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2021-11-03. Methodology: how these readings are compared.
At about 25,000 acres, Carlyle Lake is large enough that where you stay decides which shore you see most of. It has 14 public boat landings, so a lakefront rental is not the only way to get a boat on the water. Vrbo is where to look for cabins and lake homes around Carlyle Lake, and Booking.com and Expedia search hotels near the lake for your dates.
What Carlyle Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch14 documented ramps
- Camping5 public campgrounds nearby
- Big water24,580 acres
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. Carlyle Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Carlyle 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 Carlyle Lake
These are the measurements Illinois EPA publishes for Carlyle 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 238.5 µg/L. Chlorophyll-a 38.8 µg/L. TSI 73.
| 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 | 239µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 38.8µg/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. | 73 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Carlyle Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~53 ft est.
Surface area
24,580 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 Carlyle Lake.
Lake Size & Watershed
Watershed (drainage) area
2,703 sq mi
HydroLAKES / HydroSHEDS
Shoreline
59.6 mi
HydroLAKES / HydroSHEDS
Elevation
433 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
- Boulder Access MarinaPublic
- Carlyle LakePublic
- Carlyle LakePublic
- Carlyle LakePublic
- Carlyle LakePublic
- Carlyle LakePublic
Showing 6 of 14 documented landings from the USGS National Boat Ramps inventory.
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Public campgrounds near Carlyle Lake
- Lotus Group Area3.0 kmReserve
- Coles Creek Day Use3.3 kmReserve
- Coles Creek Campground3.6 kmReserve
- Boulder Campground3.9 kmReserve
- Boulder Day Use4.0 kmReserve
Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes
Stays via Stay22
Stays near Carlyle Lake
Compare lakeside cabins, hotels, and vacation rentals near Carlyle Lake in Clinton 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 Carlyle Lake are listed below.
Top-rated places to stay near Carlyle Lake
Prices for Oct 23–25, 4 adults. Change dates on the map below.
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Fishing Carlyle Lake
Reservoir Info (USACE NID)
Carlyle Lake is a man-made reservoir impounded by the Carlyle Dam - Keyesport Levee (completed 1966), built primarily for flood risk reduction on the KASKASKIA RIVER; earth-type dam, 23 ft tall and 9,945 ft long.
- Surface area
- 24,580 ac
- Normal storage
- 233,000 ac-ft
- Max storage
- 1,286,900 ac-ft
- Drainage area
- 0.9 sq mi
- Hazard class
- High
- Owner
- USACE - St. Louis District
All listed purposes: Flood Risk Reduction;Other;Navigation;Fish and Wildlife Pond;Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID IL00113 · Operator website
EPA Impairment Status
Carlyle Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Fish consumption, Other.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IL_ROA · Official waterbody report
Regulated Pollution Sources Nearby
3 EPA-permitted facilities operate within about 5 miles of Carlyle Lake under Clean Water Act (NPDES) discharge permits. 3 facilities have a reported Clean Water Act violation in the past three years.
- Department Of The ArmyCarlyle · 2.2 mi away · NPDES IL0025933Recent violation
- Hickory Shores Resort - StpCarlyle · 3.2 mi away · NPDES IL0061697Recent violation
- Eldon Hazlet State Park Campground StpCarlyle · 3.5 mi away · NPDES IL0053996Recent 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.
Nearby Lakes in Clinton County
Frequently asked questions about Carlyle Lake
Where is Carlyle Lake?
- Carlyle Lake is a lake in Clinton County, Illinois. Its water-quality measurements are published by Illinois EPA and shown on this page as reported.
What is the water quality of Carlyle Lake?
- Carlyle Lake in Clinton County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 1.8 ft visibility. Phosphorus: 238.5 µg/L. Chlorophyll-a (algae): 38.8 µg/L. Surface area: 24580 acres.
Is Carlyle Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Carlyle Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
How deep is Carlyle Lake?
- No published bathymetric survey covers Carlyle Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 53 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 24580 acres.
Are there boat ramps on Carlyle Lake?
- Carlyle Lake has 14 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Boulder Access Marina, Carlyle Lake, Carlyle Lake, Carlyle Lake, among others. Public access is listed as yes.
Can I fish at Carlyle Lake?
- Carlyle Lake has 14 documented boat landings 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.
Are there campgrounds on Carlyle Lake?
- Carlyle Lake has 5 public campgrounds from USGS The National Map within 5 km, including Lotus Group Area, Coles Creek Day Use, Coles Creek Campground, Boulder Campground. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.
Explore Carlyle 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
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Where this data comes from
93 measurements from 5 monitoring stations, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- illinois epa
IL_EPA_WQX93 samples · 2021
Analytical methods
- MEASURED IN FIELD
- Phosphorus by Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
Monitoring station identifiers (5)
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
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory
Public campgrounds from USGS The National Map Structures, within about 3 miles