One of the out – on – a – limb things that they did in the New Mexico ordinance was to claim that the groundwater was held in public trust by the county (note that this appears to be in addition to any powers they may have as alocal board of health, something I assume the county does have). That theory has been advanced in some places in New York, at least where a Township holds title to local waters because of some colonial era patent issued to the town trustees. Not sure that it would fly if tested in litigation, though, even in New York , because the context of those patents makes it pretty clear that the contemplated “waters” are surface waters e.g. lakes, bays, and the lands beneath them.
Does New Mexico local government have some powers derived from a Spanish royal charter?