Boise-area sewage treatment plant violated pollution law. What state just did
AI-generated summary reviewed by our newsroom.
- Idaho DEQ proposed a $11,000 fine for Kuna's 2022-2023 sewer violations.
- Six raw sewage overflows and excess pollutants triggered scrutiny.
- Aging equipment and population growth strain Kuna's wastewater facility.
Twenty-three thousand gallons of raw sewage overflow. Excess ammonia seeping into nearby waters. Missed requirements and botched samples.
A recent draft settlement released by the Idaho Department of Environmental Quality sheds light on violations by an aging sewer treatment plant run by the city of Kuna dating back to 2022. And it proposes fining the city $11,000, down from an initial $113,000, to get the problems resolved.
If finalized, the settlement would require the city to pay the penalty and get back into compliance with its permit with DEQ. That includes getting ammonia and residual chlorine runoff — which flows into Indian Creek, a tributary of the Boise River — under DEQ’s limits. It also means reporting things like raw sewage overflows in a timely manner.
If the city fails clean up the sewage plant’s act, it could be fined up to about $45,000 more. The remaining nearly $57,000 of the original penalty has been dropped because of “good faith and unique factors,” the draft settlement said.
Aging equipment, increased demand led to over 16 violations
Aging and failing equipment plague the Kuna’s North Wastewater Treatment Plant, which sits on Ten Mile Road on the Kuna-Meridian line, according to prior Idaho Statesman reporting. The plant, which was built in 2009, had 16 violations of the federal Clean Water Act in 2022, according to the Idaho Conservation League, an environmental group that tracks clean-water violations statewide.
Those violations were for pollutants, such as ammonia, being over the legal limits in treated wastewater released into Indian Creek. According to the U.S. Environmental Protection Agency, high levels of ammonia in water can be toxic to aquatic organisms, building up in internal tissues and blood and potentially causing death.
The proposed settlement between DEQ and the city says monthly reports from the plant showed treated wastewater above DEQ’s daily maximums of ammonia, daily maximums of residual chlorine, and monthly maximums of residual chlorine.
It also listed six instances of raw sewage overflow, including 10,000 gallons on a February day in 2023 and another 10,000 the following July.
The city also allegedly failed to report an overflow on time, failed to submit required surface-water samples in August and October 2023, and improperly stored samples collected in May 2022, “rendering samples invalid,” the settlement said.
City saw some improvements since 2022
Kuna officials and public-works staff told the Statesman in 2023 that badly needed equipment upgrades, coupled with increased strain caused by population growth, were behind the violations. Winter weather also can play a role, public works director Paul Stevens said then.
“When we do get out (of compliance) like we did, it is high stress in here,” Stevens told the Statesman. “You could cut the air with a knife. It was really bad. We took it seriously.”
In the past decade and a half or so since the plant opened, the city’s population has more than doubled, surpassing 31,000 people in 2024, according to the regional planning association.
In 2023, the Idaho Conservation League reported just two clean-water violations after the previous year’s 16.
A Kuna spokesperson told the Statesman in an email Thursday that the city was not aware of DEQ’s release and had no comment. Public works staff were unavailable to answer questions regarding any ongoing violations or compliance efforts, the spokesperson said.
Public to weigh in
Under state law, the proposed settlement is subject to a public comment period before it would be agreed to by Kuna’s Mayor Joe Stear and DEQ Director Jess Byrne.
Members of the public can submit feedback using an online form, by mailing a letter to DEQ, or by emailing ben.johnson@deq.idaho.gov. Comments will be accepted through Sept. 12 at 5 p.m.
The department is located at 1410 N. Hilton Street in Boise.
This story was originally published August 14, 2025 at 4:00 AM.
