According to the US Justice Department, the intent of the exemption is unclear, but most likely relates to an attempt to limit private speculators buying up parcels of land thought to contain valuable natural resources by allowing the government to limit the dissemination of this information. Interestingly, it's not even clear what sort of well this exemption is intended to protect, but the primary concern seems to have been oil wells rather than water wells.
It's a statement for isolationism.