Prosecutors may pursue criminal charges against the company responsible for a pipeline breach that spilled 105,000 gallons of oil into the Pacific Ocean and onto the coastline in one of California's most ecologically sensitive regions.

The May 19 pipeline spill at Santa Barbara County's Refugio State Beach has killed fish and left seabirds, seals, and other wildlife coated in thick black oil as clean-up crews have worked around the clock to try to stem the oil's environmental impact.

"I am working with the federal government and the attorney general's office to look into potential criminal and/or civil prosecution," said Joyce Dudley, Santa Barbara's district attorney, according to Reuters. Dudley's office could not be reached for comment on Monday due to the Memorial Day holiday.

Dudley said she would travel on Tuesday to meet with California's attorney general in Los Angeles to discuss the spill.

The 11-mile pipeline, called Line 901, is owned and operated by the Texas-based company Plains All America Pipeline (PAAP), and is just one section of the company's 18,900-mile pipeline network, which criss-crosses 46 US states.

The pipeline is the only pipeline in Santa Barbara County that is not required to have an automatic shutoff switch, the Associated Press reported, due to a court battle that occurred 30 years ago.

Kevin Drude, deputy director of the county's Energy and Minerals Division, told the AP that the "original owner of the pipeline skirted the Santa Barbara County requirement by successfully arguing in court in the late-1980s that it should be subject to federal oversight because the pipeline is part of an interstate network."

Federal regulations do not require automatic shut-off valves on crude oil pipelines.

"It's the only major pipeline that doesn't have auto shut-off," Drude told the AP. "For us, it's routine."

PAAP issued a statement saying that the pipeline could be shut off manually by personnel in the company headquarters in Midland, Texas, who monitor the company's network, including the Santa Barbara pipeline, 24 hours per day.

"It is much safer for controllers who understand the hydraulics of a crude oil pipeline to shut it down using a planned sequence of steps than for a computer to automatically close a valve on oil that is traveling in a confined space under high pressure," PAAP's release, attributed to Rick McMichael, Senior Director of Operations, said. "Other than reverse flow check valves, to our knowledge, the use of automatic shutoff valves on liquid pipelines in the United States is a very uncommon (or rare) due to the over pressure risk."

Environmental advocates say the company has a poor track record when it comes to pipeline safety. The Center for Biological Diversity says the US government initiated 20 enforcement actions against PAAP since 2006, mostly involving corrosion control and maintenance problems, and was fined $115,600 for two violations in 2009.

Since 2006 the company has been responsible for 223 accidents that spilled a total of 864,300 gallons of hazardous liquids, the AP reported, citing federal records. Federal regulators have taken action against the company 25 times, during which the company paid $32 million in damages, the AP said.

"This company's disturbing record highlights oil production's toxic threat to California's coast," said Miyoko Sakashita, the Center for Biological Diversity's oceans program director. "Oil pipelines and offshore fracking and drilling endanger our fragile marine ecosystems. Every new oil project increases the risk of fouled beaches and oil-soaked sea life."

PAAP released a statement saying that "safety and environmental responsibility are core values to Plains."

"Since 2008, Plains has significantly increased its size and spending related to our US integrity management and safety programs," the company said in a press release.

Meanwhile, Reuters reports that a sea lion found coated in crude oil and taken for cleaning to SeaWorld in San Diego died on Saturday. Staff at the Refugio Oil Response Unified Command, the umbrella organization overseeing the cleanup, said they did not have details on how many birds, fish, and other species of wildlife have died or are being treated as a result of the spill.

The Command is composed of the US Environmental Protection Agency, Coast Guard, PAAP, and other federal, state, and local agencies.