Local nonprofit agencies hope to share usable information on septic leachate

The Whitefish Lake Institute and the Flathead Basin Commission spoke to the city council at a work session last week about septic leachate, a problem that has been documented in the Flathead Basin since the 1970s. They also addressed the council about ways to engage the public for meaningful change.

While this issue is long-standing and ongoing, septic leachate and stormwater are two contributors to nonpoint source pollution that Mike Koopal, Executive Director of the Whitefish Lake Institute, says people can have control over.

“We can manage both better to improve water quality,” he said. “We’ve placed a high priority here at the Whitefish Lake Institute on this issue.”

According to the Flathead Basin Commission report, nonpoint source pollution can include

many different sources, like excess fertilizers, pesticides, oil, sediment, salts, as well as bacteria and nutrients from livestock. It can also come from faulty septic systems.

Septic leachate is the liquid that remains after the wastewater drains through septic solids and the pollutants it contains have harmful effects on drinking water supplies, recreation, fisheries and wildlife.

The commission’s report says that systems that are sited in densities that exceed the treatment capacity of regional soils and systems that are outdated or poorly designed, installed, operated, or maintained can pollute water resources.

The issue in the Flathead is that many of the existing septic systems are too old to function effectively. Even properly installed and maintained septic systems have a finite life expectancy of between 15-30 years depending on site-specific conditions, according to the report.

“We’re at a critical point where we’re just going to have so many septics on the landscape and so many of them are going to be aging and so it's fair to assume they're going to be underperforming or failing,“ said Koopal.

The materials that leak into the waterways and eventually the drinking water include nitrogen, phosphorus, pharmaceuticals and personal care products (PPCPs), viruses, and bacteria, all of which have a negative impact on human health and the ecosystem, the report read.

One hurdle to fixing faulty systems is that they are out of sight and often, out of mind. Koopal says pollution from the failing systems is generational and an ongoing issue.

“The generation before us really didn’t understand the issue and these septics were built where they were still functioning but now our generation is seeing the effects,” Koopal said. “These systems have aged out so it's our role to provide the mitigation or the fix so that the next generation doesn’t have to pay the price.”

In an attempt to make the complex science behind this issue easier for the average citizen to understand, the Flathead Basin Commission has created a series of maps that provide a spatial representation of the issue. It enables a homeowner to look at the area near their home and determine their risk level.

“The science is clear. What we're really doing at this point is a social issue, a cultural issue,” Koopal said. “We’ve taken the Whitefish Lake data and expanded it out… and (came) up with a visual representation of the issue which we can use for conversation.”

To determine the physical risks for one of the maps, researchers considered four factors: depth to groundwater, distance to surface water, slope and the ability of nutrients to move through soils. The result is a model that can be used to predict potential water quality impacts from existing and proposed development.

The septic age and density map identifies areas with high numbers of aging septic systems with the color red and highlights the current threat septic systems pose to water resources in Flathead County. All the Commission’s maps and the complete report can be seen on their website at https://flatheadbasincommission.org/

“We are hoping to publish a publicly accessible, online, interactive version of this risk model,” said Emilie Henry of the Flathead Basin Commission. “This isn’t intended for digging into parcel-level, it's really watershed down to a neighborhood scale.”

The Commission’s report explains that many components, besides age, go into making an efficient septic system. The tank must be well-designed. The drain field must be rigorously evaluated. Soils that are too sandy or too compact each pose problems. Additionally, the drain field must be located far enough away from water bodies so the soil microbes have time to digest.

Salts from water softeners can also plug up the holes in a septic tank, shortening the lifespan of the system.

Lake County Conservation District in cooperation with Flathead Conservation District and the Basin Commission have a septic pumping program so landowners can apply to get a rebate on having their tank pumped. That is maintenance that should be done every three to five years or based on use.

“But the problem most likely is out in the distribution field where the soil’s become so saturated and have just been played out in terms of the microbes and bacteria they can’t process the waste anymore,” said Koopal.

Montana has some of the lowest standards in the United States regarding septic systems. There are no requirements to maintain or inspect septic tanks.

To help, people could get their systems checked, pumped, maintained and/or replaced. Homeowners can also hook up to city sewer service to prevent faulty septic tanks from leaking pollutants, including human pathogens, into our waterways.