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

Sebastian County Lake Quality

Arkansas, 12 lakes, average grade F (Algae-prone)

Sebastian County holds 12 monitored lakes. With a sample that small the county-level summary describes those specific waters, not necessarily every water body in the county. 1 of those lake carry an A–F grade. The county-level summary describes that subset, not every water body listed. The county average is F — the most-stressed bracket in our rubric. Most monitored lakes here show persistent nutrient loading and algal pressure.

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. Lake Jack Nolan (F) is the cleanest in the county.

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All Lakes in Sebastian County

12 lakes · 1 graded, 11 not rated1 graded lake · 11 not rated, hidden

#LakeGradeClarityPhosphorusAlgaeTrophicAccess
1FLake Jack NolanSebastianFNo recent samples35 µg/L31.8 µg/LNo recent samplesNot recorded
NRSugar Loaf LakeSebastianNRNo recent samplesNo recent samplesNo recent samplesNo recent samples✓ Public
NRMansfield LakeSebastianNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRLake Number OneSebastianNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRLake SpurSebastianNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRGreenwood LakeSebastianNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRShadow LakeSebastianNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRBooneville LakeSebastianNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NREngineer LakeSebastianNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NROzark LakeSebastianNRNo recent samplesNo recent samplesNo recent samplesNo recent samples✓ Public
NRSebastian LakeSebastianNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRWofford LakeSebastianNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded

NR = not rated: there is not enough recent sampling to support a letter. That is EPA Integrated Reporting Category 3 (insufficient information), not a failing grade. How grading works.

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Source: EPA National Aquatic Resource Surveys, 2026.