BAKERSFIELD, Calif. (AP) &8212; A Kern County farm produced bacteria-laden lettuce that sickened 81 people in Iowa, Minnesota and Wisconsin in 2006, state and federal regulators concluded.

Wegis Ranch in Buttonwillow grew the lettuce that was contaminated with E. coli bacteria, according to a Feb. 15 final report prepared by a team from the California Department of Public Health and the U.S. Food and Drug Administration.

The lettuce was served at two Taco John&8217;s restaurants in Iowa and Minnesota &8212; one in Albert Lea and one in Cedar Falls &8212; and illnesses were reported in November and December of 2006. No deaths were reported but 26 people were hospitalized.

Regulators traced the shipments of shredded lettuce back to Wegis.

They discovered that the ranch is located near two dairies and used some wastewater from the dairies to irrigate fields where grain was grown for animal feed.

The study said E. coli samples from the ranch and the Maya and West Star North dairies were genetic matches to the strain that was found in the lettuce.

It did not definitely state how the lettuce became contaminated but said the dairy wastewater system and the ranch&8217;s irrigation system shared some piping. The irrigation system lacked proper protection against backflow that could have allowed manure-tainted wastewater to reach fields next to those where lettuce grew, the study said.

The ranch has stopped growing lettuce and the cucumbers and tomatoes it produces are processed with heat to kill germs, Mike Young, part-owner of the ranch, told the Bakersfield Californian Friday.