The bacterium that has sickened people across the nation and forced growers to destroy spinach crops is so pervasive in the Salinas Valley that virtually every waterway there violates national standards.

Federal officials said Wednesday they are focusing on nine fields in San Benito, Santa Clara and Monterey counties as possible sources of the bacteria-contaminated spinach that killed one woman and sickened at least 145 others in 23 states. Investigators also announced that spinach found in the refrigerator of a New Mexico resident who became ill tested positive for E. Coli 0157:H7, the dangerous bacteria strain responsible for the outbreak reports the LA Times.

Monterey County’s Salinas Valley is one of the world’s most intensely farmed regions and a major supplier of lettuce and spinach to the nation. The current outbreak of food poisoning marks the 20th time since 1995 that the dangerous E. coli strain has been linked to lettuce or spinach.

Many creeks and streams near the region’s spinach fields, including the Salinas River, Gabilan Creek, Towne Creek, Tembladero Slough and Old Salinas River Estuary, are known to be carriers of the E. coli strain implicated in the food poisonings. When consumed, people experience cramping, diarrhea and, in severe cases, kidney failure.

After food poisoning outbreaks several years ago, regional water officials stepped up sampling and added analysis for the deadly strain in the Salinas watershed, finding the bacteria in several waterways
next to areas where livestock graze.

Water used for drinking supplies and irrigation is not threatened by the bacteria because it is drawn from deep wells, more than 100 feet below the surface, and bacteria is readily filtered by the region’s
clay soil.

Owners of irrigation wells and private wells do not have to test for acteria or comply with the EPA’s drinking water standards, but large Salinas Valley growers test their wells anyway, at the request of
grocery chains concerned about food safety, he said.

State agricultural leaders say that if livestock are contaminating leafy green crops, they will work together because their aim is the same: Ensuring the safety of food produced in California, which has
been the nation’s leading supplier for over half a century.

The water board is now developing new limits, called Total Maximum Daily Loads, in an effort to bring the Salinas River watershed into compliance with the federal law. That could mean costly new controls on the livestock industry as well as cities responsible for cleaning up runoff.