| MTOW-1 | MTOW-2 | MTOW-3 | MTOW-4 | MTOW-5* | MTOW-6 | MTOW-7 | MTOW-8 | MTOW-9* |
| MTOW-10 | MTOW-11 | MTOW-12 | MTOW-13 | MTOW-14 | MTOW-15 | MTOW-16 | MTOW-17 | MTOW-18 |
*Note: MTOW 5 and 9 have records up to 2005.
The Illinois State Water Survey (ISWS) currently has real-time monitoring for following groundwater observation wells:
- MTOW-02 – Easton
- MTOW-03 – Wildlife Refuge
- MTOW-04 – Sand Ridge
- MTOW-06 – Tree Nursery
- MTOW-07 – IL RT-136
- MTOW-08 – Green Valley
- MTOW-10 – San Jose
- MTOW-11 – Mason City (Glasford Formation)
- MTOW-12 – Hahn Farm
- MTOW-13 – Talbot Tree Farm
- MTOW-14 – Mason City (Banner Formation)
- MTOW-15A – Ellsberry Lake
- MTOW-16 – Sand Lake
- MTOW-17 – Biggs
- MTOW-18 – Robinson