About the Program
Groundwater monitoring has replaced the "perc test" for determining where a septic drainfield can be located. Its purpose is to find the maximum height of groundwater in the area where the drainfield is planned. Flathead County Regulations, Construction Standards, and the Groundwater Monitoring Policy set out the details and requirements.
Groundwater monitoring typically takes place in the spring, when groundwater levels are at their highest in the valley. This is an important step in protecting state waters from contamination.
Groundwater Monitoring Policy (PDF)
County policy outlining groundwater monitoring requirements.
Application & Measurement Log (PDF)
Fillable application and log for groundwater monitoring.
Groundwater Monitoring Log Database
Look up recorded groundwater monitoring data.
Blank Measurement Log (PDF)
Printable blank log for recording measurements.
Groundwater Monitoring Fees
| Service | Fee Amount |
|---|---|
| Spot Check Groundwater Monitoring (1–4 pipes) | $200 |
| Spot Check Groundwater Monitoring, each additional pipe beyond the 4th | $40 |