Public Works Study Recommends Loosening Water Standards for Lower Ashley Creek

Kalispell Public Works proposed the reclassification and lowering of water standards for lower Ashley Creek during a city council meeting on Monday based on findings from a five-year study, which revealed that the current water quality standard is unattainable.

The city’s public works office initiated the study, called a Use Attainability Analysis (UAA), after city officials raised concerns that environmental factors, including natural and human-caused sources — specifically, its location downstream of the city’s Advanced Wastewater Treatment Plant — limited the stream’s ability to meet regional standards imposed by the Montana Department of Environmental Quality (DEQ).

Current state water quality standards classify lower Ashley Creek as impaired for nutrients, sediment, and water temperature. The analysis concluded the existing standards are unattainable “due to natural geomorphologic controls limiting the attainability of uses,” prompting the city’s proposal to revise them using a site-specific standard instead of a regional or statewide standard.

The study explains that the likely sources of impairment to aquatic life in lower Ashley Creek are numerous, including channelization, crop irrigation, discharges from the municipal storm sewer system, loss of riparian habitat, municipal point source discharges, and other upstream sources.

“The greatest influence on attainability of the beneficial use is due to multiple stressors,” according to the study. “The stressors include natural and anthropogenic sources and habitat-related conditions. It was not possible to diagnose a specific stressor limiting attainability of the beneficial uses in lower Ashley Creek.”

Right now, the lower creek is classified as a “wadeable stream” in western Montana, or a C-2, which designates its beneficial water usage as “suitable for bathing, swimming, and recreation; growth and marginal propagation of salmonid fishes and associated aquatic life, waterfowl and furbearers; and agricultural and industrial water supply.”

The report recommends a lower set of water quality standards for the creek that does not support swimming or sustaining salmonid fisheries. Instead, the new classification would designate the creek as suitable for growth and propagation of non-salmonid aquatic life, water temperatures at 77 degrees Fahrenheit or lower, and nutrient concentrations at a total nitrogen concentration of 3.2 milligrams per liter (mg/L) and phosphorus concentrations of 0.08 mg/L from June to September.

“Considering the [U.S. Environmental Protection Agency’s] guidelines, and based on the data collected, analyzed, and summarized in this document, it appears that the existing conditions are the highest attainable use for Ashley Creek,” the analysis states. “This is because the hydrogeomorphology of the stream dominates the possible uses, and the single largest point source has for many years achieved very high nutrient removal beyond which the facility would be rapidly approaching the practical technological limits of nutrient treatment.”

Kalispell Public Works Director Susie Turner said the project aims to protect the “highest attainable uses” of the creek ensuring creek standards are “based on site-specific science instead of inaccurate regional standards.” The city collaborated with DEQ throughout the study, Turner said.

The UAA provides five years of scientific data on the creek’s conditions, in partnership with Nebraska-based HDR Engineering, assessing the water quality, geomorphology and aquatic life based on samples from six different sites throughout the lower portion of the creek, both upstream and downstream of the city’s Advanced Wastewater Treatment Plant. It found that the lower creek is unable to meet the current C-2 water quality standards because of geomorphic controls, such as the lower creek’s lack of gravel, low gradient and “U” shaped channel form, and very low flows in late summer and early fall.  

Turner said that the data and proposed changes to the creek’s classification will help inform future decisions on what to do at the wastewater plant, and for other users of the creek.

“We can make good, informed decisions as a municipality,” Turner said. “Balancing environmental stewardship with responsible growth.”

Modifying the standards for lower Ashley Creek does not “alter the maintenance and attainment of water quality standards for downstream waters,” including the Flathead River, the UAA states. Ashley Creek provides less than about 0.5% of the inflow to Flathead Lake and less than about 5% of the total nitrogen and total phosphorus load.

Councilor Ryan Hunter raised concerns that by dubbing the water’s current conditions as natural the report avoids attributing responsibility to the human stressors resulting in those impaired conditions, and questioned how climate change could impact it in the future. Turner responded by emphasizing that the study hinges upon the existing conditions and that the system to rescind those conditions does not currently exist; she said she and the research team would follow up with more in-depth answers as she understood they were questions the public would also likely have.

“The science supports what we recommended,” Turner said. “We’re asking for a standard to match the existing uses of Ashley Creek.”

The city submitted the UAA to the DEQ for a final review in January, but the findings still must go through approval processes with the U.S. Environmental Protection Agency and DEQ, including a public comment period.

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