Idaho’s public wastewater treatment plants are failing U.S. Environmental Protection Agency standards, according to a recent report from the Idaho Conservation League, an environmental advocacy group.

The group’s third annual report found that 76 percent of the state’s wastewater plants were issued EPA permit violations between 2016 and 2018. EPA permits for wastewater treatment plants that discharge into bodies of water are required by the Clean Water Act.

The Idaho Conservation League report tracks how many times Idaho sewage plants violated EPA permits by discharging an excess amount of pollutants into bodies of water.

One or more violation over the three-year period warranted a failing grade from the Idaho Conservation League. Preston and Franklin, the only two towns in Franklin County that have a National Pollutant Discharge Elimination System (NPDES) permit, are on the group’s list of failing grades.

Franklin has had 13 violations and Preston 25. According to the report, both wastewater treatment plants had excess amounts of BOD (biochemical oxygen demand) pollutants, which can deplete oxygen from the body of water that receives the discharge. Preston also had excess amounts of ammonia and phosphorus.

As an example of what the problems posed by pollutants, ammonia, a compound of nitrogen and hydrogen, at high concentrations is harmful to aquatic life.

“When ammonia is present in water at high enough levels, it is difficult for aquatic organisms to sufficiently excrete the toxicant, leading to toxic buildup in internal tissues and blood, and potentially death,” an EPA web page says.

The Preston plant discharges into Worm Creek and Franklin’s plant once discharged into the Cub River, both of which feed the Bear River.

Just 24 percent of Idaho cities — an “abysmal” rate, according to the report — received a passing grade, meaning they had no violations in the past three years.

The report attempts to show “the state is struggling, and we need to do some work to bring folks into compliance,” said Austin Walkins, the Idaho Conservation League’s senior conservation associate.

Small cities and towns had the most violations, likely a result of lack of funding for technological improvements to sewage plants.

All of the sewage plants in the top 10 for violations serve towns and cities with fewer than 2,000 residents. Franklin has about 1,000 residents. Preston has about 5,600 residents.

“It can be tough to pay for some of these treatment upgrades, but it needs to happen,” Walkins said.

Fines levied against Idaho plants, since 2016, ranged from $2,500 to $30,000, per violation, Walkins said.

Franklin discharged into the Cub River for the last time last year, said Mayor Todd Hawkes. The city has built a storage lagoon on the south side of town in which the sewage is “treated down to where it is water, then applied to fields,” said the mayor. There are a myriad of checks to meet to be able to do that, too, he continued, but that route was cheaper than meeting the requirements of discharging into the river. The city would like to add one more level of screening garbage out of to the system, but it is essentially completed, said the mayor.

Preston City officials have taken their concerns to the public in order to raise sewage treatment fees to help make the changes required by the DEQ before some hefty fees are imposed. Already they have raised city sewage fees $10 a month per hook-up, but by October next year, there needs to be another raise of $20-$25, in order to start building a new sewage treatment plant that can handle DEQ’s requirements, said Mayor Mark Beckstead. The city has less than five years to have that system in place to avoid those fines, he said.

Two of the state’s top three offenders are in eastern Idaho. Inkom, a city of fewer than 1,000 people, topped the list, with 161 violations. The city of Driggs, population 1,800, was third with 116 violations.

Hyrum Johnson, mayor of Driggs, said the city is aware of the EPA violations and is working closely with the federal agency to address them.

While Driggs searches for a solution to the ammonia problem, it has agreed to a consent order with the EPA. The federal agency will stop issuing fines to the city of Driggs for two years.

Upgrading the facility to comply with EPA permit standards could cost $1 million, Johnson said. The sewage plant itself cost $10 million to build.

“The difficulty is in the cost of compliance,” Johnson said. “For smaller communities, the cost alone can be a real impediment.”