Dozens of federal agents led by the FBI executed search warrants in Boulder City and in the Las Vegas Valley on Thursday in an investigation of corruption in the award of a $1 million government contract for a financial audit of Hoover Dam.

The auditors were to determine if capital improvements at the dam were being incorporated into the new contracts and proper accounting standards were in place. LL Bradford & Company was chosen by the California power authority, with other entities involved in brokering the dam’s electricity — Boulder City, the Colorado River Commission of Nevada, California Edison, Arizona Power and the Metropolitan Water District of Southern California.