Blame it on an old sewage treatment plant that not enough oxygen was in the mix when Coos Bay sent treated wastewater into the bay.

Old doesn't matter, the Oregon Department of Environmental Quality essentially said this week, as it levied a $15,150 fine against the city for treatment problems last June. The DEQ announced today that the city's wastewater plant in Empire discharged water with too many suspended solids and too little oxygen.

DEQ learned about the problems through self-reported discharge monitoring reports from Coos Bay.

Although the agency relies on plant operators for their information, officials make inspections every so often to make sure everything looks all right. Officials in the agency's compliance and enforcement department only learned about Coos Bay's June violations after several months.

'There is a lag time between reviewing reports and sending issues for enforcement," said Jeff Bachman in DEQ's Portland office.

The problems have been rectified, and the city's wastewater manager, CH2M Hill, said there haven't been any violations since, said Patrick Kavan, the company's local project manager.

The city is in the process of upgrading its plant, which has brought improvements in monitoring.

'Recently we put in some new air sensors," Kavan said. 'They are more sensitive and allow us to watch the process more closely."

Andy Ullrich, a compliance engineer with DEQ, said CH2M Hill notified DEQ of the problems without specifying what went wrong.

'At the time they said they were having some operational problems, but they never gave me a definite answer," Ullrich said.

DEQ doesn't always penalize cities for problems that could affect the environment. Officials also will take into consideration whether a spill could have been prevented. Although several local cities, including Coquille on Tuesday, have had to bypass sewage into rivers in past months due to heavy rains, it's not a guarantee they will be punished. If a city has a reasonable inspection program and something breaks, then DEQ may not issue a fine. But if a city isn't making replacements frequently enough, then a city might face a violation.

'Ones that get a penalty, it has become a reasonable control question," Bachman said.

Bachman wasn't familiar with problems at other Coos County treatment plants.

In addition to having higher levels of suspended solids and lower oxygen, Coos Bay failed to do all the monitoring required of it by the state permit.

While DEQ sent the bill to the city, CH2M Hill picked up the tab, said Kavan.

'We take responsibility and our job is the protect the environment," he said.