The construction industry’s unemployment rate stood at 17 percent last month, the highest August rate ever recorded, the Associated General Contractors of America (AGC) said.

Though the sector added 19,000 jobs in August, the association said things could go downhill quickly. It’s calling on Washington to move forward on infrastructure spending bills.

“Construction layoffs in May through July offset modest job gains in March, April and August, leaving the industry with a tragically high unemployment rate last month,” said Ken Simonson, AGC’s chief economist.

“Construction job losses will resume soon unless Congress and the White House promptly finish work on long-term transportation and water infrastructure spending bills and keep income tax rates from soaring,” said Stephen Sandherr, the association’s chief executive officer.

“Stopgap funding for transportation doesn’t provide the certainty companies need for hiring,” he said. “Meanwhile, the prospect of a leap in taxes is deterring private investment.”

Over the past year, 274,000 construction workers, or 4.7 percent of the August 2009 total, have lost jobs. Of those, according to the Bureau of Labor Statistics, 123,700 were nonresidential specialty trade contractors.

“Construction began losing jobs four years ago, more than a year before the rest of the private sector, and the industry remains stuck in neutral at best, nine months after other industries started adding jobs consistently,” Simonson said.

According to an AGC analysis of Census Bureau data, total construction spending declined in July to a 10-year low of $805 billion. From July 2009 to July 2010, private nonresidential spending dropped 24 percent.