Santa Barbara County officials are still investigating the cause of a hydrogen sulfide release Sunday that caused western Goleta Valley residents to complain of strong gas odors and make multiple 9-1-1 calls about the issue. 

The Air Pollution Control DistrictOffice of Emergency Management, County Fire, and Public Health Department are investigating a release of hydrogen sulfide, which caused the sulfuric, rotten egg smell in the Ellwood area of Goleta on Sunday, county officials said in a statement Monday afternoon. 

The two potential sources are an agricultural water well and the Venoco Ellwood Onshore Facility, the former being more likely, officials said. 

The Public Health department ordered an immediate work stoppage at the well since it’s a possible source of the odors, the county said Tuesday morning. 

APCD inspectors have used hand-held monitors near the drilling to determine the source of the odors and air quality monitoring data is available online here

Generally, if a well is causing odors, it is caused by hitting a pocket of hydrogen sulfide in the drilling process, APCD public information officer Lyz Hoffman said. Water wells are typically 500 feet deep and the one being investigated is about 3,000 feet deep, she added. 

“The agencies are collaborating to ensure that air quality conditions are monitored for the affected neighborhoods. As was the case yesterday and today, odors are stronger in the morning hours,” county officials said in a statement Monday.

Hydrogen sulfide gas, or H2S, produces the sulfurous odor at a low level and causes health effects at higher levels, officials said in the release. Levels were recorded by monitoring stations located at the EOF and on Sunday morning, the levels were found to be between 0.3 and 2.6 parts per million. 

“Those levels range from generating a noticeable odor to generating some temporary health effects — such as nausea, headaches, minor respiratory symptoms, and watery eyes — following extended exposure,” officials said. 

“If you or your family members are experiencing health effects from inhaling H2S, it is recommended that you seal up your house and remain inside as much as possible. If the odors continue to cause health effects, you should leave the area until conditions improve. Sensitive individuals with more serious or persistent health effects should seek medical attention,” they said.

Air quality monitoring data from the Venoco Ellwood fence-line monitoring stations is available online here.

Santa Barbara County Fire Department crews responded to the Ellwood Canyon area four times on Sunday in response to calls about odors, described as a sulfuric smell, Capt. Dave Zaniboni told Noozhawk.

Fire personnel weren’t able to locate the source of the odor. They tested ambient air and “everything came back negative,” Zaniboni said.

There was no disclosed cause as of Monday afternoon, but Zaniboni said officials are looking into a water-drilling operation at an Ellwood Canyon home as a possible source.

Western Goleta Valley residents posted their concerns on social media, including the NextDoor groups for neighborhoods in the area. 

One resident called the lack of information about the odor’s source “beyond upsetting,” and others worried the odor was an indication of harmful chemicals, such as hydrogen sulfide, which puts off a rotten-egg sulfuric smell. 

It turns out they were right — on Monday afternoon, county officials attributed the smell to a hydrogen sulfide release and said they were still working to find the source.  

Some people initially attributed the smell to Venoco’s Ellwood Onshore Facility, located at 7979 Hollister Ave. near the Bacara Resort & Spa. Officials said it is one of the potential sources being investigated. 

The facility processes oil and gas from the offshore Platform Holly, but the operation has been mostly shut down since shortly after the Refugio Oil Spill. The ruptured pipeline was the transportation pipeline for oil headed to refineries from the facility.

A Western Goleta resident wrote to Noozhawk Sunday and said he evacuated with his family and pets after waking up around 4 a.m. to a “very strong, caustic odor that we believe was caused by Venoco Ellwood Onshore Facility operators.”

He described the smell as a strong, processed-petroleum smell. 

Daily air quality monitoring results can be found on the Air Pollution Control District website here, and a complaint can be filed with the district by calling 805.961.8810.

Check back with Noozhawk for updates to this story.

Noozhawk managing editor Giana Magnoli can be reached at Follow Noozhawk on Twitter: @noozhawk, @NoozhawkNews and @NoozhawkBiz. Connect with Noozhawk on Facebook.