The federal agency operating Hoover Dam must correct 58 health and safety violations that investigators found in recent inspections at the massive Colorado River water retention and hydroelectric power plant east of Las Vegas.

Inspectors for the federal Occupational Safety and Health Administration found violations in July and October that included lead contamination, electrical hazards, inadequate personal protective equipment and machinery guards, and the possibility that electric plant workers could be exposed to cancer-causing hexavalent chromium, according to a statement released Monday by OSHA regional chief Ken Atha.

None of the violations jeopardized the safety of the public or threatened the structural integrity of the dam or its operations, said Terry Fulp regional chief of the Bureau of Reclamation, which operates the dam that forms Lake Mead. .

"We are taking the necessary steps to ensure the issues raised are fixed and do not happen again," Fulp said.

Other deficiencies stemmed from outdated design and improved safety awareness since the dam began producing power 77 years ago, according to officials with the OSHA office in San Francisco and Rose Davis, spokeswoman for the dam operations office in Boulder City, outside Las Vegas.

None of the approximately 250 workers at the dam and its hydropower plant was injured as a result of issues that OSHA identified, Davis said.

The dam was completed in 1936 and regulates the flow of the Colorado River. It holds back the Lake Mead reservoir, which supplies almost all the drinking water supply of Las Vegas, 30 miles away. Water released through the hydropower plant supplies farms, businesses and homes downstream. The hydropower plant provides electricity to some 1.3 million homes and businesses in California, Arizona and Nevada.

Some 1 million people a year visit the dam, including about 880,000 who tour the colossal structure, its massive hydropower plant and its art deco architectural elements. They weren't endangered, Davis said.

OSHA expects a response from dam officials by the end of the month, OSHA spokeswoman Deanne Amadensaid. She added that Bureau of Reclamation officials can seek time to correct violations.

Davis said inspectors initially told dam operations supervisors they found 77 violations. Some included improper location of fire extinguishers and placement of extension cords. Some two dozen were quickly corrected, Davis said.

Other shortcomings, such as doors opening the wrong direction, date from the construction of the dam in the 1930s, Davis said.

Atha said eight violations were designated as repeat offenses because OSHA has previously notified the Bureau of Reclamation within the past five years of a similar violation at Hoover Dam or another bureau facility in the OSHA region including California, Nevada, Arizona, Hawaii and the Pacific.