Gallatin City-County Adopts Health Code Requiring nutrient-reducing septic treatment in impaired watersheds

The Gallatin City-County governing body voted April 23 to adopt amendments to health code Chapter 3 that require advanced nutrient-reduction treatment for new or increased on-site wastewater discharges in watersheds identified as impaired for nutrients.

The change, adopted by resolution 2025-001, requires systems proposed in a subwatershed that contains or immediately drains to an impaired water body to discharge effluent at no more than 24 milligrams per liter (mg/L) of nitrate plus nitrite unless a site-specific significance determination requires a different standard. The amendments also add credentialing and inspection clarifications, authorize a streamlined review pathway for early Level 2 treatment applications, and tighten enforcement and variance procedures.

The rule is intended to reduce nutrient loading from new development and expansions of unsewered systems in basins where state and local data show impairments. "These regulations are specifically important in Gallatin County to ensure that every building generating wastewater has an adequate system," Britney Kron, director of environmental health for the Gallatin City-County Health Department, told the governing body during the presentation.

Why it matters: local water-quality data and mapping included in the department packet show multiple impaired stream stretches in Gallatin County and rising nitrate concentrations in some groundwater plumes. Staff noted 29 impaired stream stretches within the county, and highlighted areas such as the Keggi (Kegi) Bench south of Bozeman where some private wells exceed 20 mg/L nitrate — well above the federal maximum contaminant level for nitrate in drinking water. Staff and presenters said those conditions increase the risk that new or expanded wastewater sources could worsen surface- and groundwater nutrient problems.

Key provisions and administrative changes - Nutrient threshold: New or increased wastewater sources in impaired subwatersheds (defined at the 12-digit hydrologic unit code level) must meet an effluent limit of 24 mg/L nitrate+nitrite, or the higher treatment level required by a significance determination. Applications proposing Level 2 treatment may use a streamlined review path defined later by department implementation guidance. - Applicability: The code does not require retrofitting of existing single-family homes that are not a new or increased source; a dwelling with up to five bedrooms within the same living unit is not treated as a new or increased source for these provisions. Separate living units (for example, a detached one-bedroom apartment) are treated as increased/new use. - Certification and operation: Advanced systems must have operation and maintenance agreements and meet current certification standards (referred to in the packet as NSF 245 or equivalent Level 2 DEQ standards). Annual maintenance and proof of pumping are required for some systems. - Permitting and inspections: The permit process includes a nonrefundable application fee once review begins, an administrative charge for commencing construction without a valid permit, revised site-evaluation scheduling (site evaluators now require one business day notice), and expanded inspection windows for installers to allow overlapping four-hour windows (for example, 8 a.m.–noon, 10 a.m.–2 p.m., noon–4 p.m.). Test pits used for site evaluation must be left open for staff review for 60 minutes. - Credentialing and enforcement: Installer/site-evaluator registration language was revised to "credentialing," including insurance and renewal training/exam requirements; the code adds fraud/omission criteria and a strike policy for credential enforcement and codifies emergency health officer septic variance practice with new public-posting requirements for variance requests.

What staff and supporters said - Staff emphasized the watershed-based approach and explained why a 12-digit watershed scale and existing state tools (mixing-zone and significance-determination analyses under state water quality law) were used to target the rule. "This proposed change will require treatment of wastewater to 24 milligrams per liter nitrate plus nitrite prior to discharge to a wastewater treatment system when located in an impaired basin," Kron said during her presentation. - The Gallatin Watershed Council submitted public comment support. Catherine Berry of the Gallatin Watershed Council told the board: "Addressing septic pollution and taking steps to mitigate continued nutrient loading is critical to stewarding our water resources for current and future generations. We're encouraged by the revisions categorized as the nutrient reduction strategy."

Concerns and costs discussed - Staff estimated an approximate additional cost of about $20,000 for a new system with Level 2 treatment in many cases, though they noted system costs vary and can be reduced by alternative designs or economy of scale for multi‑unit projects. Staff also stressed the operational benefits of Level 2 systems, which reduce nitrate by converting it to gaseous forms rather than relying on pumping alone. - Some governing-body members and commenters urged caution about imposing costs on unincorporated residents and stressed the need for continued coordination with state agencies and funding programs to assist upgrades. One member said they would register a symbolic no vote as a process concern about exceeding state law and about ensuring full county-level engagement with the Legislature.

Public process and next steps - The Board of Health held two public hearings earlier in the year and recommended the amendments to the governing body. Legal counsel explained the governing body could adopt or deny the proposed resolution as presented; amendments would require sending the proposal back for additional Board of Health hearings. - If approved, the resolution becomes effective within 30 days. Staff said they will publish implementation details, finalize a streamlined review process for Level 2 applications based on staffing and permit load, and continue outreach and education. Staff also noted ongoing work on targeted upgrades using EPA-supported funding for priority neighborhoods.

Votes at a glance - Action: Adopt County Board of Health governing body resolution 2025-001, adopting amendments to health code Chapter 3 (wastewater treatment systems). - Motion: adopt resolution 2025-001; mover/second recorded generically in the transcript as "member" and "member." (Transcript did not provide full names for the mover/second.) - Outcome: Motion carried by voice vote; majority in favor with one recorded opposed. (Transcript records two affirmative "aye" responses followed by one opposing "aye" during the roll call.)

Implementation notes - Mapping and datasets that identify impaired streams and nitrate data are available on the Gallatin City-County Health Department mapper, which links to EPA mapping data and shows nitrate causes where applicable. - Staff highlighted planned education and outreach for homeowners and installers, and noted coordination with water-quality partners (DEQ, NRCS, conservation districts, watershed groups) and with local sewer authorities where sewer extension is possible.

The governing body approved the resolution, concluding the meeting; the amendment will take effect 30 days after adoption unless otherwise specified in state rules or subsequent action.