
Harris County Lake Quality
Texas, 22 lakes, average grade D (Nutrient-rich)
Harris County's 22 monitored lakes fall in the moderate-density bracket for Texas. The county-level average smooths over real differences — a single agricultural watershed near the southwest corner can pull the average down even if the rest of the county runs clean. 3 of those lakes carry an A–F grade. The county-level summary describes that subset, not every water body listed. On average, Harris County lakes grade D, with phosphorus loading and reduced clarity showing up across most of the dataset.
The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Lynchburg Reservoir (C); the most-stressed is Lake Houston S Union Pacific Rr Bridge (F).
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Quick Answers for Harris County
Planning a trip? Check special fishing regulations for Lynchburg Reservoir — or check the official Texas fishing regulations.
All Lakes in Harris County
22 lakes · 3 graded, 19 not rated3 graded lakes · 19 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | CLynchburg ReservoirHarris | C | 1.1 ft | 98.5 µg/L | 5.9 µg/L | No recent samples | ✓ Public |
| 2 | DLake HoustonHarris | D | 0.6 ft | 780 µg/L | 26.2 µg/L | No recent samples | Not recorded |
| 3 | FLake Houston S Union Pacific Rr BridgeHarris | F | 1.3 ft | 210.5 µg/L | 36.7 µg/L | No recent samples | Not recorded |
| NRL Houston W of Lake ShadowsHarris | NR | 1.5 ft | 180 µg/L | 56.1 µg/L | No recent samples | Not recorded | |
| NRCedar Bayou LakeHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRHighlands ReservoirHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRMuleshoe LakeHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | ✓ Public | |
| NRLake SandyHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | ✓ Public | |
| NRSheldon ReservoirHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRBuckhorn LakeHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRMarshall LakeHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRMud LakeHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | ✓ Public | |
| NRLake NassauHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRTaylor LakeHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRTucker LakeHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRHegar LakeHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRMallard LakeHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRWarren Estate ReservoirHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRDennison LakeHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRSouthard LakeHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRJaphet LakeHarris | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRHegar Brothers LakeHarris | 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 Harris 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.