The Koontz Lake plate. Relief from Copernicus GLO-30; rivers and lakes from USGS NHD; watersheds from the USGS Watershed Boundary Dataset; roads and city limits from Census TIGER 2024.
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76° on Nov. 11, 2020, the hottest reading for this week of the year since 1989. Next is 73° in 2022.
Koontz Lake’s center stands about 740 ft above sea level. Within three miles the land runs from 680 ft to 790 ft, a difference of 110 ft: gently rolling country. The highest named summit within 15 miles is Reeves Hill, about 900 ft, 13 miles north-northeast.
Under the town center the state geologic map shows Antrim Shale (black-shale), from the Devonian, 359 to 422 million years old.
The section below crosses 2 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 64×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Shale. Age: Devonian to Carboniferous, 324 to 422 million years old. About 17 mi of the line.
Black-shale. Age: Devonian, 359 to 422 million years old. About 8 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale.
Heights from Copernicus GLO-90 (a surface model: it includes buildings and tree canopy); summits from USGS GNIS; rivers from USGS NHDPlus HR; rock from the USGS State Geologic Map Compilation.
A raindrop that lands in Koontz Lake reaches the Gulf of America by way of the Kankakee, the Illinois and the Mississippi: about 1,590 river miles.
Lake on the way: Peoria Lake.
1,190 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Koontz Lake; river miles along the main stem, rounded.
Koontz Lake has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 17° in January. A normal year brings about 55 inches of snow; with the rain, that comes to about 40 inches of water.
On November 14 Koontz Lake normally reaches 49° and falls to 32°. The record high is 70°, in 1999; the record low 7°, in 2019. The most rain on this date, 0.70 in, fell in 1993.
Normals 1991–2020 and records since 1989 at Plymouth, 10 miles southeast. NOAA, through RCC-ACIS.
