So what you are saying is that God heard their prayers and showed the drillers that the witching was from a bad spirit? Some here say it is from the Scriptures, others say it is from Satan, others say it doesn't work anyway. I live 26' above a great water table so it doesn't concern me.
I have seen dowsing in action and it does appear to work. Can I gurantee that the operators weren't charletans? No, I can't. But I can say that in order for the map dowser in particular to fake his findings he whould have needed to be very familiar with the site he was dowsing, more familiar than a survey crew that had spent weeks on that site.
I'm also not saying that the dowsing "gift" is always from Satan. But such gifts need to be considered with caution.