Locations
| Name | Sites | Samples |
|---|---|---|
| Hempstead County | 4 | 31 |
| Henderson County | 4 | 4 |
| Hendry County | 1 | 1 |
| Hennepin County | 12 | 29 |
| Henry County | 4 | 16 |
| Henry County | 3 | 5 |
| Henry County | 3 | 30 |
| Henry County | 10 | 23 |
| Herkimer County | 1 | 1 |
| Hertford County | 2 | 4 |
| Hickman County | 2 | 4 |
| Hickman County | 1 | 2 |
| Hidalgo County | 12 | 19 |
| Highland County | 1 | 2 |
| Highlands County | 6 | 22 |
| Hillsborough County | 7 | 24 |
| Hinds County | 2 | 14 |
| Hitchcock County | 1 | 1 |
| Hodgeman County | 2 | 9 |
| Hoke County | 2 | 3 |
| Holmes County | 6 | 50 |
| Hood County | 1 | 1 |
| Hopkins County | 14 | 99 |
| Horry County | 3 | 15 |
| Houston County | 1 | 1 |
| Houston County | 2 | 8 |
| Houston County | 8 | 14 |
| Howard County | 4 | 7 |
| Howard County | 1 | 3 |
| Hubbard County | 2 | 7 |