Jul. 19--For as long as there has been oil drilling in Ventura County, there have been oil spills.

Despite recent changes in the regulation of oil companies, nearly $1 million in fines for spilling oil into creeks, and mandated upgrades to old and corroded pipes, oil spills continue.

A Star investigation found that more than 40 percent of spills from the county's two largest companies -- Aera Energy and Vintage Production California -- in the past five years were caused by equipment corrosion. Forty percent of the spills ended up in creeks or rivers around the county.

Since 2004, more than 545,000 gallons of crude oil have been spilled by oil companies throughout the county, according to an analysis of data from the Ventura County Environmental Health Division.

"The common theme I have seen is old equipment, old pipelines," said Laurel McWaters, a Ventura County deputy district attorney who has prosecuted most of the cases against the two biggest companies.

Visual inspections of each facility are done about every four years by the state. Officials look for leaks, but no tests are done to detect corrosion.

After it was decided the inspection process wasn't rigorous enough, a new law was passed last year to increase regulations, making the producers more responsible for maintenance and giving the state greater power to fine the companies. The new rules are being finalized.

But that is still not enough for some.

Not much oversight

"They are largely self-regulated," said Paul Jenkin, environmental director of the Surfrider Foundation's Ventura chapter.

"They are required to report when they spill, but in general there is not a high degree of oversight."

Despite the law that for the first time puts guidelines beyond maintaining "good oil field practice," spills continue.

In the first six months of this year, there have been 17 spills, dumping 2,268 gallons of oil and more than 42,000 gallons of injection water, the fluid used to force oil out of the ground.

About 40 percent of the spills were because of corrosion. That's compared to 21 spills for the same time frame in 2008 and 12 spills during the first six months of 2007.

The operators are required to report spills to a number of agencies, including the California Department of Fish and Game. When Fish and Game sees a pattern of spills reaching waterways, it forwards the case to the District Attorney's Office, which can file charges against the companies. Every time the two main companies in Ventura County have had suits against them in the past 10 years, they agreed to pay the fines without admitting guilt.

Inland spills more common

Although offshore oil drilling gets most of the attention, the spills on land are much more common and result in a substantially higher amount of spilled oil, according to Assemblyman Pedro Nava, D-Santa Barbara. He got a bill passed last year that implemented random inspection of facilities and gave the state the power to shut down repeat offenders.

"No matter how safe the oil industries claim to be and how technologically advanced the equipment is, you can never eliminate the human error and you have equipment failure," he said. "The nature of the industry is it is dirty and dangerous."

Many spills are relatively small -- a few barrels from a corroded pipe -- while the largest leak of more than 400,000 gallons was from a transport company, Crimson Pipeline, in 2008.