Despite a strong grass-roots campaign against it, the ballot measure requiring the Department of Water and Power to develop a far-reaching solar power program was winning approval in early returns Tuesday.

Three other city ballot measures also appeared to be winning voter approval, while one involving the creation of an independent assessor in the Los Angeles Fire Department was trailing.

Measure B, known as the Green Jobs Initiative, would require the DWP to develop 400 megawatts of solar energy – enough to power 240,000 homes – over the next five years. It’s part of the city’s ambitious plan to develop 1,300 megawatts of renewable power by 2020.

Mayor Antonio Villaraigosa used the issue as part of his re-election effort, launching a television ad campaign over the past few weeks to bring out his supporters to the polls.

The measure has drawn a strong cross section of opposition. Beginning with a small group of protesters made up of neighborhood councils and bloggers such as former Daily News Editor Ron Kaye, the opposition eventually expanded into a wider field that included several City Council members and business groups.

Much of the criticism centered on the process used to place the measure on the ballot. Opponents said it was rushed and did not include enough public input. They also complained about the lack of study on the costs – estimates range from $1 billion to $3 billion – and how the measure required that only DWP workers under the authority of the IBEW would be used in the work.Another argument was that even if defeated, the DWP could turn around and adopt a similar program on its own, without the restrictions of a ballot measure.

Supporters of the proposal argue it would force the DWP to move away from coal-powered plants and develop a local solar industry.

Measure A, creating the post of independent assessor in the Los Angeles Fire Department to ensure programs ending racial and sexual harassment are implemented was trailing. Measures C and D, making retirement benefits for public safety officers and their families more flexible; and Measure E, allowing the city to offer financial incentives to lure new businesses, were leading.