Septic System Permiting

Process for Wastewater (Septic) Treatment System Permits

To obtain a permit application for septic systems, click here, contact sanitarian@3rivers.net, or call at (406) 466-2150.

Prior Approval

If the parcel of land is less than 20 acres, the wastewater treatment system and well should have received approval through the state Department of Environmental Quality (DEQ). These locations cannot be deviated from without approval from the DEQ.

If the parcel of land is larger than 20 acres, approval for the septic system may have been done on a county basis depending on when the parcel was created. Please provide a copy of the subdivision approval statement or the approval for the septic system. If you need assistance obtaining these documents, provide this office with the subdivision name, including legal description.

A septic system permit application is still required if you have prior approval.

Site Evaluation

If the wastewater treatment system has not received either DEQ or County approval, a site evaluation must be completed. It is the property owner’s responsibility to schedule a site evaluation. A soil test pit of at least 8 feet in depth and 2 feet in width needs to be dug. The test pit must be within 25 feet of the proposed drainfield. If the septic system is not going to be installed in a reasonable amount of time, it must be marked with a durable marker such as a 10-foot long PVC pipe buried to a depth of 8 feet.

If there is evidence of seasonally high groundwater, monitoring must be conducted during the seasonally high groundwater period (typically march to October). This monitoring is the owner’s responsibility and will be verified by the county.

If the proposed system is near the floodplain, a floodplain determination is required prior to installation. Please contact the Teton County Planning Department at (406) 466-3130 or Planning31@3Rivers.net.

Nondegradation Analysis and Water Sample

If the permit is for a new structure, you may require a nondegradation analysis. For parcels with DEQ or County prior approval, this analysis should already have been completed. For parcels without prior approval, the analysis will require a water sample for total nitrogen (nitrate plus nitrite) completed from the nearest/shallowest well. Sample containers can be obtained at the Sanitarian’s Office in the County Annex at 19 Main Ave S. The property owner is responsible obtaining the sample and paying for its analysis from a reputable agency. After receiving a copy of the water sample report, the county or state will perform the nondegradation analysis. If the property fails to pass the nondegradation requirements and does not qualify for an exemption from the nondegradation analysis, you may not have a discharging septic system at the proposed location.

Existing Septic Permit Inquiries

If you are looking for an existing septic permit, please locate the property on Montana Cadastral. When you click on the property, find the Geocode of the property within the Summary tab. The number should follow a similar format to 31-3486-25-1-28-01-0000. Email this number with your request to Sanitarian@3Rivers.net or have it available when you call (406) 466-2150.