Two canoes crossing open water between forested points in the Boundary Waters

Updated August 2026

Biggest Lake in Illinois: Carlyle Lake (26,000 acres)

Carlyle Lake is Illinois's largest inland lake per the Illinois DNR (lake administered by USACE St. Louis District). Below: 50 Illinois lakes ranked by surface area.

The largest lake in Illinois is Carlyle Lake at 26,000 acres , in Clinton (extends into Bond and Fayette) County, according to the Illinois DNR (lake administered by USACE St. Louis District). Lake Michigan is larger at 22,300 sq mi water area, 925 ft max depth (US EPA). Great Lake; Illinois holds a share of it off Chicago, which dwarfs every inland Illinois lake. Carlyle is the largest lake lying entirely inside Illinois.

See our Carlyle Lake water-quality report card F

Source: Illinois DNR (lake administered by USACE St. Louis District) (2026-07-30 (IDNR page undated)). The table below ranks the Illinois lakes in our own index by surface area.

Lakes with area data

24,580

Largest (acres)

1,426

Median of top 50

9/50

Reservoirs (vs natural)

Reading Illinois's size profile

Illinois's largest lake by surface area is Carlyle Lake in Clinton County, spanning 24,580 acres. Most of Illinois's biggest waters are natural basins left by glaciers, with stable shorelines and deep main basins.

Surface area is a poor proxy for water quality on its own — a large lake can hold a clean, deep core and a nutrient-loaded bay at the same time. Each lake below links to its full report card with grade, clarity, depth, and EPA impairment status. Area figures come from state DNR surveys and the USACE National Inventory of Dams; grades come from EPA and state monitoring data.

The 50 biggest lakes in Illinois by surface area

#	Lake	County	Surface area	Max depth	Grade
1	Carlyle Lake	Clinton	24,580 acres	-	F
2	Upper Peoria Lake	Woodford	15,461 acres	-	NR
3	Lake Shelbyville	Shelby	10,235 acres	-	NR
4	Crab Orchard Lake	Williamson	7,293 acres	-	NR
5	Senachwine Lake	Putnam	5,450 acres	-	NR
6	Lake Clinton	De Witt	4,586 acres	-	NR
7	Lake Springfield	Sangamon	4,224 acres	-	NR
8	Decatur Lake	Macon	3,335 acres	-	D
9	Lake Decatur	Macon	2,904 acres	-	NR
10	Spring Lake	Carroll	2,865 acres	-	NR
11	Cross Slough	Mason	2,776 acres	-	NR
12	Lake Chautauqua	Mason	2,723 acres	-	NR
13	Braidwood Power Plant Cooling Pond	Will	2,539 acres	-	NR
14	Kinkaid Lake	Jackson	2,500 acres	-	C
15	Lake of Egypt	Williamson	2,265 acres	-	D
16	Sangchris Lake	Christian	2,260 acres	-	NR
17	Lake of Egypt	Johnson	2,129 acres	-	NR
18	Heidecke Lake	Grundy	1,913 acres	-	NR
19	Baldwin Lake	Randolph	1,875 acres	-	NR
20	Babb Slough	Marshall	1,785 acres	-	NR
21	Horseshoe Lake	Alexander	1,785 acres	-	NR
22	Newton Lake	Jasper	1,746 acres	-	NR
23	Pistakee Lake	McHenry	1,744 acres	-	NR
24	Cedar Lake	Jackson	1,615 acres	-	NR
25	Jack Lake	Mason	1,501 acres	-	NR
26	Horseshoe Lake	Madison	1,426 acres	-	NR
27	Powerton Cooling Lake	Tazewell	1,411 acres	-	NR
28	Lou Yaeger Lake	Montgomery	1,410 acres	-	F
29	Meredosia Lake	Morgan	1,405 acres	-	NR
30	Quiver Lake	Mason	1,404 acres	-	NR
31	Stickey Lake	Fulton	1,401 acres	-	NR
32	Duck Creek Cooling Pond	Fulton	1,399 acres	-	NR
33	Lake Lou Yaeger	Montgomery	1,369 acres	-	NR
34	Miserable Lake	Fulton	1,320 acres	-	NR
35	Beebe Lake	Fulton	1,299 acres	-	NR
36	Taylorville Lake	Christian	1,269 acres	-	NR
37	Goose Lake	Marshall	1,113 acres	-	NR
38	Dresden Cooling Lake	Grundy	1,106 acres	-	NR
39	Lake Glenn Shoals	Montgomery	1,097 acres	-	NR
40	Mattoon Lake	Cumberland	980 acres	-	F
41	West Hickory Lake	Carroll	925 acres	-	NR
42	Little Grassy Lake	Williamson	905 acres	-	NR
43	Governor Bond Lake	Bond	900 acres	-	F
44	Coffeen Lake	Montgomery	881 acres	-	NR
45	Evergreen Lake	McLean	877 acres	-	NR
46	Billsbach Lake	Marshall	872 acres	-	NR
47	Upper Stump Lake	Jersey	841 acres	-	NR
48	Crane Lake	Mason	798 acres	-	NR
49	Lake Vermilion	Vermilion	793 acres	-	NR
50	Otter Lake	Macoupin	760 acres	-	F

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Frequently Asked Questions

What is the largest lake in Illinois?

Carlyle Lake, at 26,000 acres, in Clinton (extends into Bond and Fayette) County. Lake Michigan is larger at 22,300 sq mi water area, 925 ft max depth (US EPA). Great Lake; Illinois holds a share of it off Chicago, which dwarfs every inland Illinois lake. Carlyle is the largest lake lying entirely inside Illinois. Source: Illinois DNR (lake administered by USACE St. Louis District), 2026-07-30 (IDNR page undated).

How is lake surface area measured?

Surface area comes from state DNR lake surveys and, for reservoirs, US Army Corps of Engineers (USACE) National Inventory of Dams records. Area is reported in acres at normal pool level. Reservoirs rise and fall with management and drought, so their listed area is the long-term normal rather than a single-day reading.

Are Illinois's largest lakes natural or reservoirs?

Of the top 50 Illinois lakes by area, 9 sit on a dammed river (reservoirs) and 41 are natural basins. Glacial states (MN, WI, MI, NY) skew natural; plains and southern states (MO, IA, ND, OH) skew toward reservoirs built for water supply, flood control, and recreation.

Do larger lakes have better water quality?

Not reliably. Quality varies more within a big lake than between lakes — a large lake can have a clean, deep main basin and a murky, algae-prone bay fed by a tributary, so one grade can mask wide swings. Depth, watershed land use, and how fast the lake flushes matter far more than raw surface area.

How big is the typical Illinois lake in this ranking?

Across the top 50 Illinois lakes by surface area, the median is 1,426 acres (Horseshoe Lake). This list is biased toward the biggest waters; the typical Illinois lake is far smaller.

Where to stay near Illinois's largest lakes

Planning a trip? Jump to live cabin, resort, and hotel availability near Illinois's biggest lakes.

Deepest lakes in Illinois →Cleanest lakes in Illinois →Largest lakes (all states) →All Illinois lakes →