A significant potential source of contamination is sewage. Areas of the county not served by community wastewater treatment facilities utilize onsite wastewater disposal systems that dispose of sewage into the ground rather than being treated and released back into a river. Gradually the percolation of sewage through the soil, if not properly treated, can contaminate our groundwater, which is also the source of our drinking water.
The following guidelines and documents are used to make sure that any proposed
onsite sewage treatment system, or major repairs or modifications to existing systems, are reviewed and approved prior to construction.

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Individual Sewage Treatment System Permit Application Form

Montana DEQ Circular 4

EPA Onsite Wastewater Treatment System Information

Inspecting, Designing, Maintaining Residential Septic Systems