What is the cleanest lake near Jefferson Lake?

O'Fallon Park Lake in St. Louis city County holds a Grade D water quality score and is 4.1 miles from Jefferson Lake.

Why is Jefferson Lake not Grade A?

Jefferson Lake holds Grade D and 70 µg/L of phosphorus. The grade reflects measured water quality against Metropolitan Council thresholds. Cleaner alternatives nearby score higher on clarity, phosphorus, or chlorophyll-a.

Are these recommendations based on real data?

Yes. Every grade is calculated from EPA Water Quality Portal samples for the lake. Recommendations are limited to lakes within 30 miles of Jefferson Lake in Wisconsin, with strictly higher numeric grade scores and sufficient monitoring data.

Cleaner Lakes Than Jefferson Lake, Top 5 Within 30 Miles, LakeQuality

Cleaner Lakes Than Jefferson Lake

5 higher-graded lakes within 30 miles, ranked by grade improvement and proximity.

Jefferson Lake carries a Grade D (Poor) water quality score. Within 30 miles, 5 lakes hold a higher grade. O'Fallon Park Lake (St. Louis city County, Grade D, 4.1 mi away) is the closest meaningful upgrade.

O'Fallon Park Lake

St. Louis city County, Wisconsin · 4.1 mi from Jefferson Lake

+Higher overall water quality score

Boathouse Lake

St. Louis city County, Wisconsin · 5 mi from Jefferson Lake

+Higher overall water quality score
+Lower phosphorus (59.8 vs 70 µg/L)

Forest Park Pond

St. Louis city County, Wisconsin · 1 mi from Jefferson Lake

+Higher overall water quality score

Lafayette Park Lake

St. Louis city County, Wisconsin · 3.2 mi from Jefferson Lake

+Higher overall water quality score

Simpson Park Lake

St. Louis County, Wisconsin · 11.8 mi from Jefferson Lake

+Higher overall water quality score

How this list is built

Every lake on LakeQuality has a calculated grade from EPA Water Quality Portal samples — secchi depth, total phosphorus, and chlorophyll-a measured against Metropolitan Council thresholds. To suggest cleaner alternatives, we filter lakes within 30 miles to those with a strictly higher numeric score, then rank by grade improvement with a small proximity tiebreak. Cross-state and limited-data lakes are excluded so the list stays locally relevant.