Technical Comments Submitted Concerning New Major Subdivision Pollution Permit That Will Further Degrade the Lower Gallatin

 Decisionmakers fail to consider cumulative impacts of more sprawl development

On Wednesday, Upper Missouri Waterkeeper submitted comments to the Department of Environmental Quality (DEQ) questioning the proposed approval of yet another new major subdivision’s polluting septic system in the Gallatin Valley’s high-growth triangle, just upstream from Baxter Creek, McDonald Creek & Hyalite Creek. At issue is the scientific and legal adequacy of DEQ’s review of likely water resource impacts in a proposed Montana Ground Water Pollution Control System permit for the R Bar N Estates Subdivision.

“Montana DEQ is, yet again, proposing to rubber stamp new septic pollution permits for sprawl development that is likely to exacerbate ongoing nutrient pollution problems in our local creeks and streams,” said Guy Alsentzer, Executive Director of Upper Missouri Waterkeeper. “With unprecedented development at an all-time high in the Gallatin Valley and expert science already showing ongoing river pollution challenges, DEQ must stop turning a blind eye to the negative cumulative effects of major development on our waterways.”

The project in question, R Bar N Estates Subdivision, is a 177-unit subdivision located in the high-growth triangle between Belgrade and Bozeman off E. Valley Center Road, and just 1,000’ upgradient of Baxter Creek. Baxter Creek is a tributary of nearby Hyalite Creek, which in turn is a primary tributary of the E. Gallatin River. The subdivision proposes the use of a community septic system discharging an average of 44,250 gallons per day into local groundwater. Septic systems are a significant source of water quality degradation across western Montana. Septic systems do not effectively remove nitrate from wastewater, and therefore contribute unnaturally elevated levels to groundwater.

DEQ’s review of the new subdivision’s wastewater disposal plan indicates that local groundwater quality is already significantly degraded by cumulative nutrient pollution: the average nitrate concentration in test wells was 4.5 mg/L, as compared to natural background levels below .5 mg/L, a nearly tenfold increase. The federal EPA’s maximum contaminant levels for groundwater nitrogen concentrations are 10 mg/L; when nitrate concentrations approach 10 mg/L there are significant human health risks, including blue baby syndrome. DEQ’s permit proposes allowing the new subdivision to discharge wastewater with nitrate concentrations up to 7.5 mg/L. Nitrate and total nitrogen are chemical derivatives of residential wastewater.

Despite these data points and well-known booming development patterns across the Gallatin Valley, DEQ’s permit materials failed to adequately consider how adding yet another major new nutrient pollution source could exacerbate existing water pollution trends.

Equally troubling is the lack of scientific diligence concerning how a new major subdivision and more septic pollution will specifically affect downgradient local streams and creeks.  

For over 50 years Montana’s expert water scientists have demonstrated that river valleys like the Gallatin possess interconnected groundwater and surface water systems.  During the cold winter months groundwater in alluvial valleys like the Gallatin tends to flow into and add to local streams, creeks, and rivers. During runoff season, creeks and streams, particularly in the headwater mountainous elevations, tend to lose flow and add volume to local groundwater. This give and take between groundwater and surface water is part of the natural makeup of western Montana’s river valleys, and is well-established by scientific research from the state’s groundwater experts at the Montana Bureau of Mines and Geology.

DEQ’s proposed new pollution permit turns a blind eye to these scientific realities and makes the dubious claim that downgradient streams from the new major subdivision – such as Baxter and Hyalite Creeks – are ‘hydrologically disconnected’ from receiving groundwater. This same theory of ‘disconnected’ hydrology is DEQ’s rationale for claiming the proposed new discharge permit won’t degrade local surface water. DEQ’s permit and conclusions are simply wrong.

For nearly a decade the E. Gallatin River, including many of its primary tributaries like Hyalite Creek, have been designated by DEQ as impaired by nutrients, meaning excessive pollutant loads, and in particular contributions of nitrogen, have degraded these waterbodies’ ability to support sensitive designated uses such as aquatic life and fishing opportunities. The DEQ approved clean-up plans for the E. Gallatin and Hyalite Creek among others specifically recognizes the harmful effects of cumulative nutrient pollution from widespread use of septic systems to groundwater and, in turn, to local surface waters.  

Despite this well-established scientific backdrop DEQ has proposed rubber-stamping yet another major new subdivision and polluting septic system in Montana’s fastest growing county without taking a hard look at cumulative effects or the likelihood of continuing the degradation of nutrient-impaired surface waters like Hyalite Creek and the E. Gallatin River.

DEQ must conduct a thorough analysis of how yet another major subdivision and polluting septic system will affect groundwater and surface water quality in the Gallatin Valley. In the face of sprawling growth between Bozeman, Belgrade, and Four Corners and unrelenting pressure on our backyard streams, it’s more important than ever that DEQ prioritize science-based decisionmaking that protects local water quality.