| County | Land Area Acres | Acres Overlying the Aquifer |
| Finney | 830,808 | 739,419 |
| Grant | 368,115 | 368,115 |
| Hamilton | 640,047 | 608,044 |
| Stevens | 466,497 | 466,497 |
| Total | 2,305,047 | 2,182,075 |