Spinach growers and processors will not face criminal charges over an E. coli outbreak last year that caused the death of three people and sickened 200 others, including one Ottawa woman.

On Thursday, U.S. Attorney Scott Schools said an investigation found farmers and processors were not negligent and had not intentionally tried to break the law.

Authorities in California searched processing plants and additional farms in the state's Santa Clara, Monterey and San Benito counties.

What is E. coli?
E. coli stands for Escherichia coli, bacteria commonly found in the intestines of animals and humans.

Last September, Canadian and American health officials told consumers not to eat bagged or bunched spinach for fear of E. coli contamination. An investigation confirmed that the E. coli strain O157:H7 was present in the recalled spinach products.

The O157:H7 strain, a deadly form of the bacteria, contaminated water in Walkerton, Ont., in 2000, killing seven people.

In late October, the Canadian Food Inspection Agency lifted its import restrictions on U.S. spinach and U.S. officials declared the outbreak over. Meanwhile, investigators searched for possible causes of the contamination including runoff, flooding, irrigation, fertilizer and wildlife.

In late October, the Canadian Food Inspection Agency lifted its import restrictions on U.S. spinach.
(CBC)

Officials later determined the contaminated spinach was grown in San Benito County. Cattle and pig feces samples taken from a neighbouring ranch contained the same E. coli strain found in the tainted spinach.

Recall rattled consumer confidence

Before the E. coli outbreak, health-conscious Americans had driven up demand for the convenient, bagged spinach. California farmers increased production of the leafy greens from 15,000 acres in 2001 to 31,000 in 2005.

While growers and health officials vowed to introduce more rigorous safety checks, consumer confidence was rattled. In the aftermath of the recall, researchers with Western Growers, an organization representing farmers in California and Arizona, said the outbreak caused unmatched financial losses of around $74 million US.

With files from the Associated Press