Locations
| Name | Sites | Samples |
|---|---|---|
| Perry County | 1 | 1 |
| Perry County | 4 | 50 |
| Peru | 108 | 288 |
| Pettis County | 1 | 1 |
| Philadelphia County | 3 | 14 |
| Pickens County | 2 | 11 |
| Pickett County | 2 | 22 |
| Pike County | 1 | 1 |
| Pine County | 1 | 3 |
| Pinellas County | 12 | 88 |
| Pitt County | 1 | 9 |
| Pittsburg County | 1 | 9 |
| Pittsylvania County | 5 | 17 |
| Plaquemines Parish | 6 | 14 |
| Platte County | 3 | 6 |
| Poland | 363 | 2150 |
| Polk County | 1 | 3 |
| Polk County | 6 | 32 |
| Polk County | 1 | 6 |
| Polk County | 1 | 10 |
| Polk County | 3 | 5 |
| Polk County | 1 | 4 |
| Pontotoc County | 1 | 10 |
| Pope County | 2 | 3 |
| Portugal | 105 | 247 |
| Pottawatomie County | 2 | 2 |
| Potter County | 2 | 5 |
| Potter County | 8 | 50 |
| Powell County | 8 | 23 |
| Powhatan County | 1 | 8 |