Union County Lake Quality
North Carolina, 3 lakes, average grade F (Very Poor)
Union County has 3 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. 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 Twitty (D) is the cleanest in the county.
Quick Answers for Union County
Planning a trip? Check special fishing regulations for Lake Twitty — or check the official North Carolina fishing regulations.
All Lakes in Union County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Lake Twitty | D | - | 80 µg/L |
| 2 | Lake Lee | F | - | 210 µg/L |
| 3 | Lake Monroe | F | - | 110 µg/L |
Other Counties in North Carolina
See how Union County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 12 states.
Where to stay near Union County
Top-rated places to stay near Union County
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Source: EPA National Aquatic Resource Surveys, 2026.