Anacortes and Friday Harbor now have more in common than the state ferries.

Sewage.

Wastewater — specifically, activated sludge — from Anacortes is being trucked to the Friday Harbor wastewater treatment plant Friday to repopulate the wastewater system with micro-organisms that break down sewage.

Town Administrator King Fitch said the microorganisms in one of Friday Harbor’s treatment tanks died. The result: Wastewater from the 250,000-gallon tank is being disinfected with industrial-strength bleach. But the treated wastewater being discharged into the harbor is failing state standards for clarity.

The treated wastewater being discharged into the harbor is disinfected, but it’s cloudy, Fitch said.

The town has notified the state Department of Ecology that it is violating the standards of its wastewater discharge permit. The town will not be fined because it notified Ecology and is taking steps to correct the problem.

One effect from the movement of sludge into the system: Neighbors may notice the smell for a couple of days, Fitch said.

Fitch said the microorganisms may have been killed off by something toxic that was put into the system — not an attempt at humor here. “We don’t know,” he said. “We’ve done tests for toxicology but we don’t have a report back. It’s month-old evidence, so we may not find anything.”

Fitch said the microorganisms could have been killed off by a substance such as benzene, fuel or formaldehyde that was put down the drain.

Brad Musick, a consultant with Kennedy/Jenks Engineers and Scientists, noticed a spike in the amount of dissolved oxygen, or oxygen saturation, back in mid-March. The town’s system uses oxygen to feed the microorganisms that break down the sewage. Low dissolved oxygen levels means those microorganisms are active and working. More dissolved oxygen means fewer microorganisms at work.

Microorganisms break down the sewage by dissolving the solids. The wastewater then is disinfected with ultraviolet light. If the wastewater is not clear, then the ultraviolet light can’t get through. The town then must use chemical disinfection, in this case industrial-strength bleach, to thoroughly disinfect.

The town hoped to reintroduce live microorganisms into the system with four tanker loads of activated sludge — a total of 24,000 gallons — trucked in from Anacortes Friday.