Joliette County Lake Quality
Québec, 1 lakes, average grade A (Excellent)
Joliette County has 1 graded 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. On average, Joliette County lakes grade an A. That puts it near the top of the Québec county ranking.
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. Lac du Rocher (A) is the cleanest in the county.
Quick Answers for Joliette County
Planning a trip? Check special fishing regulations for Lac du Rocher — or check the official Québec fishing regulations.
All Lakes in Joliette County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Lac du Rocher | A | 15.1 ft | 7.4 µg/L |
Other Counties in Québec
See how Joliette County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 38 states.
Where to stay near Joliette County
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Source: EPA National Aquatic Resource Surveys, 2026.