After several months of tiny taps and minor blows, the big hammer is coming down on U.S. wind power jobs.

Citing a dearth of new orders — caused in no small part by the pending expiration of the production tax credit for wind — Siemens said yesterday it would lay off 615 wind workers in three states.

Siemens Kansas wind nacelle factory

image via Siemens

Most of the job losses will come in Iowa, where 407 of the more than 600 workers at a Fort Madison blade factory are being put out of work, the Des Moines Register reported.

The mass Iowa layoffs come mere days after a coalition of individuals and organizations in the state sent a letter to the Iowa Congressional delegation urging an extension of the PTC in order “to stop further job losses and to halt economic deterioration in Iowa and throughout the nation.”

If only it were up to the Iowa delegation; earlier this year [PDF], all four of the state’s U.S. representatives as well as both senators – Democrat and Republican alike – endorsed an extension of the PTC.

For Siemens, the move represents a big retrenchment on a U.S. expansion plan that began to unfold toward the end of the last decade. Beyond the turbine factory in Fort Madison, Siemens has its headquarters in Orlando, Fla., and an operations center in Houston; Boulder, Colo., is home to an R&D center; Elgin, Ill., has two gearbox factories; and there’s a nacelle factory in Hutchinson, Kans.

In addition to Fort Madison, job cuts this round are coming in Kansas and Florida. The Witchita Business Journal reported that 146 workers were being laid off in Kansas, accounting for nearly half of the Hutchinson plant’s 298-person workforce. All the cuts together will leave the company’s U.S. wind employment roll at around 1,000 people.

In a statement to employees, Siemens listed the uncertainty over the PTC as the first factor in its decision, but also pointed to competition for new energy development from low-priced natural gas as well as “the lingering recession” as contributors. “As a result, following the rapid ramp-up of the wind power industry over the past five years, the industry is facing a significant drop in new orders, and this has an unfortunate consequence on employment in this segment of the power industry,” the company said, according to North American Windpower.

While the job losses mount, there’s little sign that Congress will move on the PTC, at least not before the election — to the chagrin of Rep. Dave Loebsack (D-Iowa). “Congress should not be going home to campaign at a time when so much critical work remains unfinished,” Loebsack, whose 2nd Congressional District includes Fort Madison, said in a statement. “The livelihood of thousands of Iowans depends on the renewal of the credit.”whose 2nd Congressional District includes Fort Madison, put out a statement that “