Water Quality | Grass Valley Gardens, LLC | Grass Valley Gardens Residential Subdivision | Missoula County | Comment Period Closes July 9, 2026
APPLICANT:
Grass Valley Gardens, LLC
FACILITY NAME:
Grass Valley Gardens Residential Subdivision
FACILITY LOCATION:
14N 20W 20SW, Missoula County
46.955904ᵒ, 114.162644ᵒ
RECEIVING WATER:
Outfall 001 - Class I Ground Water
PERMIT NUMBER:
MTX000331
This is a major modification of Montana Ground Water Pollution Control System (MGWPCS) Permit MTX000331 issued to Grass Valley Gardens LLC for the Grass Valley Gardens Residential Subdivision. The modification includes revisions to effluent limitations and supporting calculations following DEQ’s identification of an error in the original effluent limitation calculation after permit issuance. The revised calculations result in more stringent effluent limitations. The modification does not change the authorized design flow, treatment system, disposal method, or discharge location.
The proposed major modification also includes revisions to the compliance dates associated with installation of required monitoring wells.
The facility is designed to handle up to 120,000 gallons per day of domestic wastewater utilizing a Membrane Bioreactor (MBR) treatment system and Rapid Infiltration Cells (RICs) for subsurface disposal to Class I ground water through Outfall 001 located in the SW¼ of Section 20, Township 14 North, Range 20 West, Missoula County, Montana.
Associated Materials:
Comment Period Ends: July 9, 2026
Send Comments To:
DEQ Water Quality Division
Water Protection Bureau
PO Box 200901
Helena, MT 59620
Or electronically to: DEQWPBPublicComments@mt.gov
Tags: MEPA, Public Comment and Water