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LakeQuality
Late afternoon sun over Slim Lake, scattering a bright path across wind-textured water

Randolph County Lake Quality

Illinois, 8 lakes, measured by Illinois EPA

Randolph County has 8 monitored lakes — a thin enough sample that one or two stressed lakes can move the county average noticeably. Use the per-lake pages below for what actually matters. 3 of those lakes carry recent nutrient and algae readings. The county-level summary describes that subset, not every water body listed. The monitored lakes here are mostly shallow, productive basins where summer algae is common; each lake page shows its own readings beside the EPA condition class.

Most of the county's monitored lakes are shallow, under 50 feet, which means wind keeps the water column mixed all summer and sediment-bound phosphorus releases back into the surface layer whenever the bottom is disturbed. Randolph Lake has the lowest nutrient and algae readings in the county.

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Where to stay near Randolph County

Top-rated places to stay near Randolph County

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All Lakes in Randolph County

8 lakes · 3 ranked on readings, 5 without enough sampling3 lakes ranked on readings · 5 without enough sampling, hidden

#LakeClarityPhosphorusAlgaeTrophicMax DepthAccess
1Randolph LakeRandolph1.7 ft87.5 µg/L44.9 µg/LNo recent samplesNo recent samples✓ Public
2Sparta Northwest LakeRandolph2.6 ft44.5 µg/L32.5 µg/LNo recent samplesNo recent samples✓ Public
3Coulterville LakeRandolph2.7 ft452.5 µg/L51 µg/LNo recent samplesNo recent samplesNot recorded
Randolph County LakeRandolphNo recent samplesNo recent samplesNo recent samplesNo recent samples35 ft✓ Public
West C Streamline LakeRandolphNo recent samplesNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Old City ReservoirRandolphNo recent samplesNo recent samplesNo recent samplesNo recent samples16 ft✓ Public
New City ReservoirRandolphNo recent samplesNo recent samplesNo recent samplesNo recent samples12 ft✓ Public
Baldwin LakeRandolphNo recent samplesNo recent samplesNo recent samplesNo recent samples48 ft✓ Public

NR = no nutrient or algae reading on record. The measurements are published as the authority reports them. Where the data comes from.

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Source: the Illinois Environmental Protection Agency. See data sources.