Memorandum
REPORT TO:
City Commission
FROM:
Brian Heaston, Engineer III
Shawn Kohtz, Director of Utilities
SUBJECT:
Authorize the City Manager to Sign a Memorandum of Understanding with the Montana Department of Environmental Quality to Revise the Nutrient Total Maximum Daily Load for the Middle Segment of the East Gallatin River
MEETING DATE:
October 27, 2026
AGENDA ITEM TYPE:
Agreement - Agency/Non-profit
RECOMMENDATION:
Authorize the City Manager to Sign a Memorandum of Understanding with the Montana Department of Environmental Quality to Revise the Nutrient Total Maximum Daily Load for the Middle Segment of the East Gallatin River
STRATEGIC PLAN:
BACKGROUND:
The entire length of the East Gallatin River is impaired by nutrient pollution from its origin at the confluence of Bear Creek and Rocky Creek to its terminal mouth at the West Gallatin River. The Montana Department of Environmental Quality (DEQ) holds primacy over implementing the total maximum daily load (TMDL) program of the federal Clean Water Act. A TMDL is a pollution cleanup program that identifies pollutant reduction targets necessary to achieve underlying water quality standards and thus remediate impairment conditions caused by pollutants.
The City’s water reclamation facility (WRF) removes over 90% of nitrogen and phosphorous that enter the plant during the summer season before discharging treated effluent to the middle segment of the East Gallatin River. These nutrients are essential to support biological life at the proper quantities. However, excess nutrients, can cause dense algal growth that may impair designated uses of a waterbody (e.g. aquatic life, recreation, drinking water, etc.). The middle segment of the East Gallatin River begins at Springhill Road and ends at the mouth of Smith Creek north of Belgrade.
An EPA-approved nutrient TMDL was completed for the middle segment of the East Gallatin River in 2013. This TMDL contains a nutrient pollution limit for the WRF that was derived from the state’s numeric nutrient water quality standards that were effective for regulatory purposes at that time. During the 2025 Legislative Session, the state enacted law that replaced these numeric nutrient standards with a narrative standard. This narrative replacement was approved by EPA. The 2013 nutrient TMDL must now be revised to reflect the narrative standard. The TMDL revision must be approved by EPA to become officially recognized for Clean Water Act purposes. Once the revised nutrient TMDL is approved by EPA, its nutrient reduction targets must be implemented in the City’s discharge permit as enforceable limits.
The attached memorandum of understanding (MOU) sets forth respective roles and responsibilities of the City and DEQ for the nutrient TMDL revision process. The City will accomplish the bulk of the technical work needed to derive nutrient reduction targets that achieve narrative nutrient water quality standards. DEQ has authority to review and approve, or modify, the City’s technical work to produce a revised nutrient TMDL that satisfies state and federal requirements.
UNRESOLVED ISSUES:
The City plans on engaging HDR Engineering to perform the technical work needed to revise the nutrient TMDL. HDR has completed the City’s prior water quality monitoring and modeling efforts for the East Gallatin River and currently holds the City’s on-call contract for WRF engineering services. It is thus best positioned to perform this work and provide best value. The City Commission will see a consent agenda item in the near future requesting task order authorization for HDR to complete the TMDL revision.
ALTERNATIVES:
As suggested by the City Commission.
FISCAL EFFECTS:
The adopted FY27 budget contains $300k in the wastewater fund capital improvements plan for the TMDL revision (Project Code WW164). Supplemental funding is presently planned in the FY28 capital plan in the amount of $100k in the event additional services are necessary to complete the TMDL revision work as it progresses towards completion.