| Basin and Range basin-fill aquifers |
| Basin and Range carbonate-rock aquifers |
| California Coastal Basin aquifers |
| Central Valley aquifer system |
| Colorado Plateaus aquifers |
| Columbia Plateau basaltic-rock aquifers |
| Columbia Plateau basin-fill aquifers |
| Northern Rocky Mountains Intermontane Basins aquifer system |
| Other rocks |
| Pacific Northwest basaltic-rock aquifers |
| Pacific Northwest basin-fill aquifers |
| Rio Grande aquifer system |
| Snake River Plain basaltic-rock aquifers |
| Snake River Plain basin-fill aquifers |
| Southern Nevada volcanic-rock aquifers |
| Upper Tertiary aquifers |
| Willamette Lowland basin-fill aquifers |
| <all other values> |