Waterkeeper Raises Concerns on Proposed Hyalite Creek Major Subdivision

Subdivision Threatens Local Water Availability and Water Quality; Commission Should Deny Application

On Monday, October 24, Upper Missouri Waterkeeper submitted comments to the Gallatin County Commission opposing the proposed Hyalite Creek major subdivision, echoing concerns from the Gallatin Local Water Quality District about water resources protection. The Commission is hosting a public hearing on Tuesday, October 25 at 9am to approve or deny the preliminary plat for the major subdivision.

The project in question, Hyalite Creek Major Subdivision, is a 31.57-acre tract divided into 31 residential lots located on the south side of South 19th Avenue between Cottonwood Rd and Cougar Dr. This subdivision proposes extreme density as compared to surrounding properties. The subdivision is also proposing the use of several exempt groundwater wells for water supply, despite nearby landowners’ concerns that local water table levels in private wells are already dropping. The subdivision also proposes the use of septic systems for each individual residence. These bare minimum proposals have raised concerns about the sustainability of local water quantity and quality from Waterkeeper, the Gallatin Local Water Quality District, and nearby residents. 

Septic systems do not effectively remove nitrate from wastewater, and therefore contribute unnaturally elevated concentrations of this pollutant to groundwater. High levels of nitrate are a threat to human health, and similarly high nitrogen levels in surface water are linked to noxious algal blooms and degraded aquatic habitat. Local groundwater in the subdivision region is already experiencing rising nutrient levels above natural background, which is particularly concerning given both Hyalite Creek and the Lower Gallatin River are already impaired by excessive nutrient pollution as a result of cumulative inputs from sprawl development and individual septic systems. 

The exempt well challenge is also front and center for the Hyalite Creek major subdivision. Since the watershed Montana Supreme Court case of Clark Fork Coalition v. Tubbs (2016), the law of the land has been that a new subdivision is limited to the use of one exempt well for the entire development proposal. Yet the developers behind Hyalite Creek proposed the use of two groundwater well zones using a total of 16 exempt wells, contrary to the Montana Supreme Court’s verdict in CFC v. Tubbs and to the Dept. of Natural Resources and Conservation’s own combined appropriations regulations.

“Denying the Hyalite Creek Major Subdivision is an easy opportunity for Gallatin County decisionmakers to get ahead of the curve, listen to the science, and do better for water resource protection in the Gallatin Valley,” said Guy Alsentzer, Executive Director of Upper Missouri Waterkeeper. “New development projects need to prove up-front they are adequately protecting our local waterways and that sufficient water supply exists. Hyalite Creek hasn’t shown it can do so, and therefore it shouldn’t be approved. It’s hard to put the genie back in the bottle once individual wells and wastewater septics are approved.”

The Gallatin Local Water Quality District provided comments on the Hyalite Creek Subdivision along the same lines as Waterkeeper, recommending the subdivision be required to invest in centralized advanced sewage treatment system in lieu of individual septic systems to “provide an increase in oversight and maintenance that helps to protect water quality and human health.” The District also pointed out the likelihood of highly transmissive, shallow groundwater and potential impacts to water supply and nearby surface water. 

The Gallatin County Commission should follow the guidance of County expert water scientists, require the Hyalite Creek Major Subdivision to both prove its water supply up to a centralized wastewater treatment system, and do their part to ensure water quality challenges aren’t worsened by new development projects.

In addition to the opposition from local scientific experts, Gallatin County citizens, and Waterkeeper, the Gallatin County Planning Board has recommended that the County Commission deny the preliminary plat for the Hyalite Creek Major Subdivision.

The Governor’s Housing Task Force recommendations have suggested delegating more control of local environmental protection review to local government. If local government is to take an increased role in managing local development projects, these entities need to squarely address significant water quality and quantity issues with new major subdivision projects like Hyalite Creek. Gallatin County has the authority and responsibility to do a better job at controlling the known, cumulative pollution from sprawl development, and that should start with following the facts and making science-based decisions that protect public health, water availability, and local water quality.