As a backdraft to an ongoing investigation of utility infrastructure involvement in the Northern California wildfires, a still-incomplete attempt to map utility transmission lines is raising questions about how effective regulators and utilities have been in taking preventive action.

The California Public Utilities Commission (CPUC) and state fire officials are investigating the extent to which, if any, Pacific Gas and Electric Co. (PG&E) transmission facilities played a role in sparking some of region’s horrific wildfires.

The CPUC a decade ago began a mapping project that apparently has never been fully implemented.

Within days of the wildfires, which have killed at least 42 people and destroyed more than 5,000 homes, PG&E and other state utilities were said to have been given a 74-day extension on the mapping project deadline.

A CPUC spokesperson said that “a good amount of the mapping work has been done and more is scheduled to be completed soon.”

Following Southern California wildfires in October 2007 that were attributed todowned San Diego Gas and Electric Co. (SDG&E) power lines, the CPUC initiated a rulemaking and eventually adopted regulations for electric and communications utilities that have overhead transmission lines in high-risk fire areas. The requirements included more frequent foliage trimming away from utility lines and patrol inspections by the utilities.

The CPUC proceedings resulted in development of a fire-threat map that has been under review since July, which outlines more than 74,000 square miles of both elevated and extreme fire risk areas of the state. Overall, 47.2% of the state’s land is included in the fire-threat map with more than half (55.6%) in Northern California.

The issue has stirred one of PG&E’s harshest critics, state Sen. Jerry Hill. He told reporters he may seek to break up the San Francisco-based combination utility’s natural gas and electric divisions.

In comments to the San Francisco Chronicle, Hill said if PG&E were found to have contributed to the outbreak of the wildfires, “then frankly I don’t think PG&E should do business in California anymore.” He represents San Bruno, where in 2010 a PG&E gas transmission pipeline ruptured, killing eight people and injuring scores in a residential neighborhood. “They’ve crossed the line too many times,” Hill said. “They need to be dissolved in some way, or split.”

PG&E officials said the recent time extension on the utility mapping was requested by the California Forestry and Fire Protection, or Cal Fire, in a Sept. 25 letter. However, PG&E and SDG&E submitted the request on behalf of Cal Fire, which is not a party to the ongoing CPUC proceeding, so it could not file the motion.

A PG&E spokesperson said the utility has been working with Cal Fire, the CPUC, other energy companies and stakeholders “to develop new utility fire threat maps and new fire safety regulations that protect our communities and customers.”

PG&E plans to continue to focus on ways to reduce the threat of wildfires from the most extreme fire threat areas. “Ultimately, we will support the proposal that will ensure the greatest protection, reduce the threats of wildfires, and minimizes the impact on our customers and their communities,” he said.