Robert Arnold and his wife, Deanna Arnold, worked at Wright County's Galt facilities for several years. The Arnolds said they shared their concerns with USDA workers perhaps a dozen times.
"I seen junk coming in on the belts where the eggs come from the barns, food wrappers, tools, a cat, mice," Robert Arnold said. "I complained. Nothing got done."
"They just let the chickens run loose and they weren't feeding them or watering them," Deanna Arnold said. "They were freezing to death. When the spring came, there was hundreds of birds laying between each of the barns where they dropped dead from freezing all winter."
Though USDA employees worked at the farms full time, Deanna Arnold said they did nothing when she tried to report such conditions to them.
"I reported it to the USDA worker that was there. She seen it and she knows. They weren't doing anything about it. They would just let it go," Deanna Arnold said.
Egg Recall: Wright County and Hillandale Farms
Wright County Eggs and Hillandale Farms -- about 100 miles from each other -- recalled a total of more than half a billion eggs in mid-August after nearly 1,500 people were sickened by salmonella linked to eggs in recent months. The number of people sickened is expected to climb.
Wright County is owned by Jack Decoster, who has paid millions of dollars in fines and settlements during the years stemming from complaints about the health violations at his farm.
At Wright Egg and Quality Egg, part of the Wright complex, Food and Drug Administration inspectors found live mice inside the egg-laying houses, live and dead flies "too numerous to count," as well as live and dead maggots "too numerous to count," according to an FDA report released Monday.
At Hillandale Farms, inspectors found 65 "unsealed rodent holes," as well as "liquid manure" streaming out of a gap in a door. They also found nearly 50 "un-caged hens tracking manure ... to the hen house area."
Robert Arnold said that when he tried to complain to supervisors, they told him that he could quit if he didn't like the conditions of his job.
The USDA said that it did not investigate the safety of eggs and that its workers never entered the hen houses because they are not allowed to.
What's more, Caleb Weaver, an agency spokesman, said that the employee who oversaw the grading of eggs at the Wright County site did not recall anyone raising issues.
Weaver said an investigation into the claims was still continuing.
USDA employees were only on the farm to "grade" the eggs -- check their quality, size and thickness.
It's up to the FDA to oversee egg safety. The FDA had never inspected the farms before the salmonella outbreak. The agency says, until recently it did not have the authority to do routine inspections, but could have checked out the farm if it had known of any complaints.
Did FDA Drop the Ball on Egg Farm Recall?
Patty Lovera, assistant director of Food and Water Watch, a non-profit consumer group, said the USDA argument that it was not its job to enter hen houses technically was correct.
"It's a little sad that they [the USDA] can't pick up a phone and call the people whose job it is to investigate this," she said. "They know it's the FDA's job. They could have called them. They could have blown the whistle and, hopefully, speeded up this process before people got sick."
In a statement today, Agriculture Secretary Tom Vilsack said the "USDA has been working to close gaps and improve the safety of the meat, poultry and processed egg products over which we have authority and the FDA is taking action to address the fact that they have not had all of the tools needed to prevent outbreaks in areas where they have authority, such as shell eggs. "
The Arnolds said there were a lot of good egg producers following the rules.
"DeCoster [the owner of Wright County] is so huge in the business that it's hard to control a lot of it," he said.
In a statement today, Wright County Eggs said, "Anytime there is a perceived issue on our farm, we expect our employees to immediately bring it to our attention, so that we may address it appropriately and swiftly. That is our policy, and that is their responsibility. To the best of our knowledge, no concerns were ever raised."
The owners of Hillandale and Wright County have been asked to testify before Congress later this month.
ABC News' Chris Bury and affiliate KCRG in Cedar Rapids, Iowa, contributed to this story.