What is DEQ proposing?
The Montana Department of Environmental Quality (DEQ) has released a Draft Programmatic Environmental Assessment (EA) for the construction and operation of subsurface wastewater treatment systems (SWTS), aka septic systems. The department is currently accepting public comment on the proposed EA until May 1.
Why are conservation groups raising the alarm on this proposal?
The draft EA prioritizes streamlining residential development over protecting water quality. The department is attempting to make it easier to approve SWTS without taking a hard look at potential impacts – direct, secondary, or cumulative – that this sector has on our local water resources.
What are subsurface wastewater treatment systems (SWTS)?
DEQ defines SWTS to consist of up to four main components that disturb less than 10 acres during construction and operation. Those four main components are:
- Wastewater collection system (service connections and/or sewer mains) – A wastewater collection system conveys wastewater from the wastewater source(s) to a septic tank. A building service connection, which is a pipe, connects a building’s internal wastewater collection system to a sewer main or directly to a septic tank. When multiple service connections connect to a central sewer pipe(s), the sewer pipe is considered a sewer main. Wastewater flows from a service connection to the sewer main and then into a septic tank.
- Treatment facility – Subsurface wastewater treatment facilities collect, hold, and treat influent wastewater before sending treated effluent to a disposal structure. A treatment system may be as simple as a septic tank that provides primary treatment, or it may also include an advanced treatment system attached to the septic system that provides secondary or tertiary treatment.
- Distribution system – Incoming wastewater displaces treated effluent, which exits the system and is distributed to the absorption system. Distribution may be driven either via gravity or by passing into a pump chamber where it is dosed into the absorption system via a pump or siphon.
- Soil absorption system – Effluent from a treatment system is discharged through subsurface piping onto porous surfaces that allow wastewater to filter though the soil. The soil accepts, treats, and disperses the wastewater as it percolates through, ultimately discharging the wastewater to ground water if ground water is present below the absorption system site.
Why is wastewater from SWTS a problem?
Domestic wastewater is a major and growing source of pollution in Montana. As residential development expands, the cumulative impacts of many individual septic systems degrade water quality, harm fisheries, and threaten public health and drinking water supplies. This is not hyperbole, but best-available science affirmed by DEQ and EPA: more than 30% of assessed surface waters in Montana are already polluted by excessive nutrient pollution, and diffuse septic systems are a leading contributing sector to those water quality challenges.
Much of Montana’s groundwater and surface water are hydrologically connected, meaning pollution discharged into groundwater will reach nearby rivers, streams, and lakes. Because of this, it’s critical that DEQ does its job to protect Montana’s groundwater from pollution. This Draft EA, however, proposes streamlining permitting for most domestic wastewater discharged to groundwater, instead of using strong science to condition individual permit applications to protect water resources.
What is a “programmatic” Environmental Assessment, and why does it matter?
A programmatic EA evaluates a broad category of actions rather than site-specific projects. This approach allows DEQ to approve large numbers of septic systems under generalized assumptions, rather than conducting detailed, site-specific reviews. This approach is a detriment to our waters, as it prioritizes quick rubber-stamped permits instead of meaningful review designed to prevent pollution.
What are the main issues with the Draft EA?
- It prioritizes speed of development over environmental scrutiny.
- It relies too heavily on engineering standards that may still create significant impacts on our water resources.
- It fails to address cumulative impacts.
- It ignores existing water quality problems.
- It conflicts with Montana’s constitutional guarantees.
- It reduces public participation in government decision-making.
Read more on the main issues here.
What are cumulative impacts?
Cumulative impacts refer to the combined effect of many individual SWTS over time. While one system may have a small impact, many systems in the same watershed can significantly degrade water quality. The Programmatic EA does not adequately evaluate or account for these combined effects.
Engineering standards are not designed to evaluate direct, indirect, or cumulative impacts. A project can meet engineering standards and still contribute to environmental harms, especially when combined with other projects.
What are conservation groups calling on DEQ to do?
The coalition is calling on DEQ to shelve the Programmatic EA, and instead, revise and strengthen regulations for SWTS and land use controls for residential development to prevent and abate the proven, negative cumulative impacts from SWTS on Montana’s waterways. This should include requiring site-specific and cumulative impact analyses and ensuring robust public participation opportunities in decision-making.
What happens next?
DEQ is accepting public comments on the Programmatic EA until May 1, 2026. After the comment period closes, the department will respond to comments, and revise, finalize, or withdraw the proposed EA.
What can you do?
You can submit public comments to DEQ standing up for the protections Montana’s waterways deserve here.