Most days on this water start at a ramp on a reservoir. Carlyle Lake is the largest the pack carries, 22,684 acres, and Lake Shelbyville at 10,181 acres would fit inside it twice over with room to spare. Upper Peoria Lake measures 15,370 acres and Crab Orchard Lake 7,265. Below that tier the names on the chart get less famous and a good deal more interesting, because they run to sloughs, backwaters, ponds and a cooling pond at a power plant, and most of them have a ramp on them somewhere.
The pack carries 5,368 charted water bodies. Of those, 1,543 are named, and 118 of the named ones are larger than a square kilometer, which is about 247 acres. Set against the other 47 state lake packs, that is sixteenth by water bodies, eighteenth by named water and nineteenth by lakes over a square kilometer, so all three land in the upper half. The outlines come from the USGS National Hydrography Dataset, so a reservoir here is charted as a named outline with its real shoreline.
Helm splits inland lake coverage into 48 state packs. This one is sixteenth by charted water bodies, eighteenth by named water and nineteenth by named lakes over a square kilometer. Three ranks sitting inside four places of each other says something about the shape of the water here. There is no single enormous lake dragging a count upward. There is a lot of water, spread out, most of it modest in size.
Of the 5,368 water bodies in the pack, 3,825 carry no name on the chart. They still have an outline. An unnamed oxbow off a river bend is charted water the same way Carlyle is.
Of the 1,543 named waters, only 118 clear a square kilometer. The other 1,425 come in under 247 acres, which is the size of water a lot of people fish on a weeknight.
| Lake | Charted surface area |
|---|---|
| Carlyle Lake | 92 km² (22,684 acres) |
| Mine Number 21 Reservoir | 69 km² (16,976 acres) |
| Upper Peoria Lake | 62 km² (15,370 acres) |
| Lake Shelbyville | 41 km² (10,181 acres) |
| Crab Orchard Lake | 29 km² (7,265 acres) |
| Senachwine Lake | 22 km² (5,412 acres) |
| Lake Geneva | 22 km² (5,387 acres) |
| Lake Clinton | 18 km² (4,571 acres) |
| Lake Springfield | 16 km² (3,880 acres) |
| Horseshoe Lake | 13 km² (3,188 acres) |
| Spring Lake | 12 km² (3,089 acres) |
| Broad Pond | 12 km² (2,916 acres) |
The twelve largest named lakes the Illinois pack carries, by charted surface area, measured from the chart polygon itself. The pack carries 5,368 charted water bodies in all, 1,543 of them named, and 118 named lakes larger than one square kilometer.
NOAA charts the coast and the intracoastal, and the Army Corps charts the navigable rivers. The water bodies in this pack come from the USGS National Hydrography Dataset, which describes where the water sits and what it is called.
A reservoir also sits at whatever level it is being held at. Summer pool, a winter drawdown, a week of rain upstream and a gate opened somewhere below: the level moves, and the shoreline moves with it while the outline on the chart stays where it was drawn. The cove you idled through in June is a place to trim up and crawl in October.
So treat the outline of a reservoir as the charted extent rather than today's shoreline.
Carlyle Lake is the largest named water the pack carries, 91.8 square kilometers, or 22,684 acres. Mine Number 21 Reservoir is next at 16,976 acres, and Upper Peoria Lake after that at 15,370. Lake Shelbyville, which nobody would call small, comes in at 10,181.
Below the top four the drop is steep. Crab Orchard Lake is 7,265 acres. Senachwine Lake is 5,412 and Lake Geneva 5,387, which puts 25 acres between them. Then Lake Clinton at 4,571, Lake Springfield at 3,880, Horseshoe Lake at 3,188 and Spring Lake at 3,089. Lake Decatur is 2,891 and Kinkaid Lake 2,323, and Kinkaid at that size is about a tenth of Carlyle. All of these figures are measured off the chart polygon itself, so they are the surface the chart actually draws rather than a number from a brochure.
Names near a state line turn up in more than one pack. The packs are cut to a box rather than to the state line, so water over toward the Wisconsin, Iowa, Missouri or Kentucky side can sit in two packs at once. Lake Geneva is one of those. If the water you run is near a border, the pack next door carries it as well, and the coverage overlaps instead of stopping at the line.
Some of the larger named water in this pack is not what most people picture when they hear the word lake. Broad Pond is 2,916 acres. Cross Slough is 2,768. Quiver Lake and the Braidwood Power Plant Cooling Pond are both 2,520 acres to the acre, which is a coincidence and nothing more, and is still the sort of thing you notice reading down a chart list. Here is that whole band, the named water in the pack between roughly 2,400 and 3,000 acres:
Water like that is charted the same way the big reservoirs are, as a named outline from the hydrography dataset. Nine of the twenty largest named waters in this pack are under 3,000 acres, which is a size you can cross in a few minutes and still run aground on.
The state lake packs draw lake shorelines from the USGS National Hydrography Dataset, and a reservoir sits at whatever level it is being held at that week. Treat the shape as a guide, keep a lookout, and verify locally.
Carlyle is on the chart by name and outline, drawn from the USGS National Hydrography Dataset, and it is the largest named water the pack carries at 91.8 square kilometers, or 22,684 acres. Of the 48 state lake packs, Minnesota is the one with depth contours.
Because the lake is held at a level and that level moves. Shelbyville covers 10,181 acres at the chart polygon, an outline from the USGS National Hydrography Dataset, and that outline does not change when the pool is drawn down. The water line does. Check the pool the lake is sitting at that week and give the shallow edges more room.
Both can. The packs are cut to a box rather than to a state line, so water near a border appears in more than one of them. Lake Geneva is in this pack at 21.8 square kilometers, or 5,387 acres, within 25 acres of Senachwine Lake in the same list. If the water you run is near the line, download the neighboring pack as well and the two overlap.
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