Report uncovers 6,000 unpermitted septic systems

A recently released report on sewage treatment in the Flathead Valley uncovered about 6,000 unpermitted septic systems. That brings the total number of septic systems in the valley not connected to treatment plants to more than 20,000. That translates into about 4.1 million gallons of wastewater every day.

“These numbers are huge, but it must be understood that these quantities of wastewater are being discharged over a very large area,” the report states. “There are, however, areas with high densities of septic systems where the quantity of wastewater effluent being discharged is a concern. Especially if the soils in these areas are not capable of adequately treating the wastewater before it migrates to ground or surface water.”

Carver Engineering, of Kalispell, was hired by the Flathead Regional Wastewater Management Group, a task force representing local governments, state and federal agencies, and other stakeholders, to prepare the region-wide strategic plan.

In addition to septic systems, the report includes information on capacity, current use and future demand for 12 sewer districts with treatment plants, from Big Mountain south to Polson, as well as a chapter on sewage pumpers.

Flathead County Health Officer Joe Russell said the task force wanted to create an the in-depth study as a planning tool for the county’s Board of Health. A state grant paid for the report and its detailed maps.

Looming in the background was a long-standing concern of nutrient pollution harming the pristine water quality of Flathead Lake, the underground aquifer that runs along the Flathead River and groundwater all across the valley. There were also concerns about a movement toward stricter discharge standards under the umbrella label “total maximum daily load,” or TMDL.

“TMDLs drove the process to some extent,” Russell said, “as well as some grousing by municipalities and treatment plant owners.”

According to the report, an accurate count of septic systems is difficult to obtain. Carver Engineering began with the 14,952 septic systems logged in the county’s GIS database and the 21,276 permits on file with the Flathead City-County Health Department.

To reconcile the figures, Carver Engineering had to take into account permits for septic system replacements, septic systems built before the permit system initiated in the late 1960s, septic systems at vacant mobile home lots, and septic systems installed illegally without a permit.

Using the premise that residential or commercial structures outside of a sewer district must have a septic system, Carver Engineering turned to the Montana Cadastral Mapping Web site used by the state to identify dwellings for tax purposes. The result was 6,026 assumed septic systems identified without a permit.

The report also addresses septic system failures. While noting that Flathead and Lake counties “have been and continue to be at the forefront in developing progressive rules and regulations” for septic systems, standards that other counties follow, Carver Engineering pointed out that most of the rules have only been in effect since 1980s or even 1990s.

Septic systems fail because of age, improper construction, inadequate maintenance, incorrect soils — even leaking plumbing fixtures that overload the system. To extend the life of a drainfield, the report says, “it is commonly recommended to pump a septic tank every three to five years.” Actual pumping frequencies, they discovered, appear to be about every 10 years. This was in line with the general neglect septic systems face.

“System owners are not likely to repair or replace a failing system unless sewage backs up into their residence or commercial structure, or until sewage ponds on the ground surface,” the report states.

Russell said the Carver Engineering report needs to be “dynamic” and put to good use. The task force continues to meet, he said, and is addressing additional challenges, such as potential water quality impacts by pharmaceutical and personal care products dumped into toilets or drains. Some areas of the valley need more attention than others.

“You’d be surprised at how bad the data is for septics along Whitefish Lake,” he said. “Permitted, unpermitted, connected to city sewer — you can’t find the correct figures.”

Russell said he plans to have health department staff spend a week walking the shoreline of Whitefish Lake, knocking on doors and getting the details on individual septic systems.

“Failing septic systems must be repaired,” Russell said. “It’s the law.”

For more information on the Carver Engineering report, visit online at http://flathead.mt.gov/wastewater_management/index.php.