Emergency crews responding to an ammonia leak on the Clipper Epic. Photo by Zac Schasteen.

Emergency crews were mopping up an ammonia leak from a boat at the OSI dock on Unalaska's Captains Bay Road midday Friday. They blocked off the road at the Crowley dock Friday morning, about a half mile closer to town, as they responded to the leak. At 11 a.m., Unalaska police officers moved the road block closer to OSI, stopping traffic just before the main entrance to the facility. 

As of 12:30 p.m., OSI employees were still sheltering in place. Coast Guard and Unalaska Public Safety personnel were on the scene.

Officials said there was no imminent public health threat.

One person went to the Iliuliuk health clinic for minor exposure to ammonia, according to deputy police chief Mike Holman. Iliuliuk clinic director Eileen Scott said the patient is in stable condition.

Trident worker Anthony Garcia was driving through the OSI complex just after the leak happened.

"I just caught the tail end of it, saw the white smoke, looked like an ammonia cloud leak, you know, wasn't sure exactly what it was but it looked like everybody was off the boat, evacuating, doing what they had to do," Garcia said.

Ammonia is used as a refrigerant. It can severely damage the eyes, skin and lungs at very small concentrations. Holman said if you can smell it, you should probably back away.

Ammonia is invisible at low concentrations, but it can look like smoke when it's concentrated. Holman said the first reports they got at 9:15 a.m. were of smoke from a fire.

"Responders got on scene, smelled ammonia, they backed off and set up incident command over at the Crowley area," Holman said. "They had folks at the OSI complex shelter in place, then we evacuated Crowley area in anticipation that the cloud could possible move that direction based on forecast wind." 

Fire officials have been spraying water on the Clipper Epic from the Port of Dutch Harbor's rescue boat, the Tidebreaker, to knock the ammonia cloud out of the air.

Managers at OSI said the ammonia leak on board the Clipper Epic has been contained, but the fumes have not been cleared yet.  

Fire chief Zac Schasteen said they're using fans on the boat deck to ventilate the inside of the boat, but he said it's slow going since the boat has a lot of compartments. Schasteen said they've let people and boats return to the Crowley and Shell facilities but that OSI is still sheltering in place.

The Clipper Epic is a 170-foot long-liner processor boat.

At 11:30 a.m., Holman said he expects they'll have the incident cleaned up and the road reopened within a few hours.