Richard Kuprewicz was zipping down the California coastline Tuesday when a powerful stench wafted into his car. Just feet away, thousands of gallons of oil were spilling into the ocean below, blanketing the Santa Barbara Channel with a 9-mile-wide sheen. Kuprewicz didn’t pay much attention to the dark oil clouds that washed up in the waves and turned the sandy beaches into toxic mud. “I was trying to get out of the vapor cloud,” he recalled.

For Kuprewicz, it was a “weird coincidence” that he was driving on Highway 101 that particular afternoon. He’s normally based in Washington state, where he works as a pipeline safety consultant for energy companies, regulators and the public. The acrid odor seeping into his windows reinforced what Kuprewicz has known for years: America’s oil pipelines -- and their regulations -- are in major need of repair.

Across the U.S., pipelines leak on a nearly daily basis. Nearly 450 spills occurred last year along 50,000 miles of oil pipelines, federal data show. Often leaks are small and easily contained, but occasionally they occur in hard-to-miss, hard-to-clean areas like the California coast. Pipeline experts such as Kuprewicz point to two key reasons for the frequent spill rate: inadequate pipeline management systems and spill response plans on the part of operators, and weak federal regulations to ensure effective spill prevention and response.

“Our pipeline system is proving increasingly susceptible to failures, and all of this is playing out in the context of a regulatory regime that’s proven incapable of assuring safety,” said Anthony Swift, a staff attorney and pipeline safety expert at the Natural Resources Defense Council, a national environmental organization. “The Santa Barbara spill, while tragic in its consequences, is not an outlier or an exception.”

Tuesday’s incident began around noon PDT after a 24-inch underground pipeline ruptured and leaked up to 105,000 gallons of oil into the ocean, according to Houston-based Plains All American Pipeline LP, the conduit’s owner. Plains managed to shut the pipeline down around 3 p.m., it said. On Wednesday, Gov. Jerry Brown declared a state of emergency in Santa Barbara County as crews began cleaning up the spill -- the largest in coastal California in decades.

Crew members and federal regulators will be digging up the pipeline this week to determine what physical or chemical factors might have caused the leak. The 11-mile Plains American Coastal Pipeline connects to Exxon Mobil’s Las Flores Canyon crude oil refinery, though Exxon has not been implicated in the spill.

“Plains deeply regrets this release has occurred and is making every effort to limit its environmental impact,” the company said in a statement Tuesday. “Our focus remains on ensuring the safety of all involved.”

Darren Palmer, the district manager for Plains, told local media that the company’s monitoring equipment had not alerted it to the Santa Barbara spill. Instead, a member of the public called about the leak, and Plains manually shut down the pipeline shortly afterward. The company had run a leak detection probe, called a “pig,” through the pipeline two weeks earlier, but the results had not come back before the rupture, Palmer said at a news conference.

Kuprewicz said the fact that Plains’ monitoring system didn’t immediately detect the leak is fairly typical of U.S. oil pipelines. Even as companies install more systems and invest in sophisticated technologies, “It doesn’t necessarily mean it will work when you really need it,” he said. “It’s not unusual for a pipeline to have a massive rupture and not show up in the control room.”

In fact, remote spill sensors detected only 5 percent of the nation’s pipeline spills between 2002 and July 2012, InsideClimate News, an environmental news site, found when it examined data from the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administrator. Pipeline company employees at the scenes of accidents reported 62 percent of the spills during that period, while the general public reported 22 percent of spills, the data show.

Plains executives agreed in 2010 to take steps such as “enhanced pipeline leak detection” and “enhanced integrity management and corrosion control” to minimize the risk of future spills. The U.S. Environmental Protection Agency had cited Plains for 10 oil spills totaling 273,000 gallons in Texas, Louisiana, Oklahoma and Kansas. To settle the case, Plains agreed to pay a $3.25 million civil penalty and spend millions more to upgrade its system, the Los Angeles NBC affiliate reported Wednesday.

Kuprewicz said detecting and preventing leaks requires more than just upgrading sensors and monitors. “Throwing more equipment at it isn’t necessarily the right solution; it creates an illusion of safety,” he said. “We need to get more information out about how we can improve in areas where it would be effective. It’s a more complicated issue than parties want to talk about.”

Pipeline companies and federal officials similarly need to revamp their emergency response plans, Swift said. “We’re using many of the same techniques for marine oil spills that we did in the 1969 Santa Barbara spill,” he said, referring to the notorious offshore oil well blowout that dumped as many as 100,000 barrels of crude oil into the channel and killed thousands of seabirds.

During the 1969 cleanup efforts, responders dropped chemical dispersants from airplanes to help break up the oil and expedite its biodegradation. A similar strategy was used following the 2010 BP oil disaster in the Gulf of Mexico, but the practice is controversial. While dispersants get rid of thick globs of oil, they make it easier for plants and wildlife to absorb the toxic chemicals, so that the oil never really disappears, scientists say.

In Santa Barbara this week, cleanup crews have used only skimmers, vacuum trucks and absorbent booms to collect oil from the water, according to Plains. On Refugio State Beach and El Capitan Beach, both now closed to the public, workers are using shovels, garbage bags and absorbent pads to remove the sticky sludge.

Still, crews are unlikely to recover all 105,000 gallons of spilled oil, particularly as crashing ocean waves and shifting tides make it hard to cull and remove the crude. After the BP disaster, which dumped more than 100 million gallons of oil into the Gulf, only about 5 percent of crude was fully removed during the response, U.S. Coast Guard researchers estimated.

Kuprewicz said it was still too early to comment on Plains’ recovery efforts. But in general, companies’ oil response plans and related federal regulations don’t do enough to ensure that, when oil leaks, the crude is quickly and thoroughly removed. The plans “have some serious gaps in them,” he said. “They just aren’t effective.”