Lettuce Fields' Irrigation Water Contaminated?

RE Washington Post article "Calif. Lettuce Recalled Over E. Coli Concerns" (link below under green or salmon print):

One thing the FDA and CA farmers don't want you to realize is that all leaf crops in CA are grown with ground water pumped up and then supplied to the roots for irrigation according to reports on the spinach crisis. (It was reported once and then disappeared which is what happens to most information that would harm big business in this nation at its best).

Because Central Californian soil is reported to be heavy clay in the leaf crop region and the water table low (at least it was in the years and places I lived there), bacteria cannot make it's way down to 'ground water' (the italicized assessment also came from a news report on the spinach crisis).

Cattle do not enter vegetable crop fields for some various obvious reasons available at a moment's thought. Like in many other places they have their own fields. Also, we do not in general see flooding rains in summer in low land California. Though I have not followed the weather up where the fields are this summer.

Therefore, it seems that the bacteria must have come into the system after coming up again for irrigation.

Restrooms for fieldworkers can be up to 1/4 mile away from the fields and the workers are often pushed to get more picked than ever before for their poor pay. (From report about worker conditions in CA fields).

Make your own inferences from that. Are we finding that allowing American business to abuse their employees is now killing us?