Williamson County Lake Quality
Texas, 8 lakes — no lake here has enough monitoring data for a grade
Williamson County holds 8 monitored lakes. With a sample that small the county-level summary describes those specific waters, not necessarily every water body in the county. No lake in Williamson County has enough sampling behind it for an A–F grade yet. The 8 monitored lakes below carry whatever clarity, phosphorus, and chlorophyll-a measurements exist.
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.
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Quick Answers for Williamson County
Planning a trip? Check special fishing regulations for Lake Georgetown — or check the official Texas fishing regulations.
All Lakes in Williamson County
8 lakes · 0 graded, 8 not rated0 graded lakes · 8 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| NRLake GeorgetownWilliamson | NR | 5.6 ft | 20 µg/L | 9.4 µg/L | No recent samples | ✓ Public | |
| NRSite Number TwentytwoWilliamson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRSite Number EighteenWilliamson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRSite Number Four AWilliamson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRLake GeorgetownWilliamson | NR | No recent samples | No recent samples | No recent samples | No recent samples | ✓ Public | |
| NRGanzert LakeWilliamson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRMuir LakeWilliamson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRLake Will WilsonWilliamson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not 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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Other Counties in Texas
See how Williamson County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all United States (49 states), Canada (Ontario, Québec, Nova Scotia, British Columbia and Newfoundland and Labrador), and 38 other country hubs..
Source: EPA National Aquatic Resource Surveys, 2026.