For those who drive the winding course of Vasco Road, the change was swift and startling. The vast, rolling landscape familiar to commuters for its picturesque hills and groves of standard wind turbines suddenly – apparently overnight – became a sci-fi landscape dominated by 400-foot behemoths.

“It was a sight,” said Darrell Newby, who commutes from Brentwood to Livermore along Vasco Road. “I’ve never seen anything so big. It took me a few minutes to figure out what they were.”

“They” are new state-of-the-art windmills, part of a $190 million turbine re-powering plan known as the Vasco Wind Project. NextEra Energy, which owns roughly half of the 4,000 wind turbines along the 50,000-acre Altamont Wind Resource Area, is replacing the standard windmills as part of a settlement agreement with the state attorney general’s office and the National Audubon Society that required the energy company to either remove or repower the outdated turbines by 2013.

The Vasco Wind Project is the program’s first phase. It involves replacing 438 of the 20-year-old turbines with 34 of the newer, more efficient models. According to Steve Stengel, spokesman for NextEra, the new 2.3-megawatt machines, manufactured by Siemens, will power between 500 and 600 homes annually.

“Basically for the same number of megawatts being used now, we will be able to power many more homes with far fewer turbines,” said Stengel. “It’s a great project; it’s going very well.”

The new turbines tower 326 feet above the landscape. Each of the three rotor blades is 150 feet long; nearly the width of a football field. And in high winds, the blades can spin at a speed of up to 180 miles per hour.

But the project’s eco-friendliness, said Stengel, can be measured in more than dollars. “There are really two over-arching benefits to this project: the turbines are so much more efficient that we will be able to get much more renewable energy out of them, and there is a huge environmental benefit to the avian impacts. It’s a great opportunity to accomplish both.”

Unlike the older lattice-style structures, the new turbines are mounted on monopole towers absent perching areas for birds. The new design, combined with the decrease in the number of turbines and better placement, will make for a more bird-friendly environment that some say could reduce avian mortality by as much as 80 percent.

“The real benefit to all this is that everyone who has studied the issue out in Altamont believe the project will significantly reduce the problem (avian deaths),” said Stengel.

The Altamont Wind Resource area is one of the oldest wind farms in the nation. When first built in the 1970s, it boasted nearly 6,000 turbines. Companies such as NextEra lease the land’s wind rights from area farmers and cattle ranchers.

The plan also includes the removal of 180 power poles (throughout the Altamont Wind Farms, which includes a stretch of Vasco Road), 6½ miles of overhead line, 15 guide towers and 23 miles of road.

The ongoing construction of the windmills along Vasco Road, in concert with the lane-widening project near Brush Creek, can be distracting for drivers who travel the curvy 16-mile corridor. So as a condition of approval for permitting the new, taller turbines, the Contra Costa County Board of Supervisors required NextEra to sponsor a safety radio spot for Vasco Road.

According to Stengel, the Vasco Wind Project is expected to be complete by the end of the year. The remaining phases of the Altamont Wind Resource Project will follow. By the time the work is done in 2013, not only will Alameda and Contra Costa counties’ rolling hillsides be more energy-efficient – they’ll be prettier.

“We think that once the project is completed, the landscape will look completely different,” said Stengel. “It will look a lot cleaner from an environmental perspective and it will be much better. It’s a good project.”