You can have a pre-existing well, or a "household use only" (read: can't irrigate, water your yard, or provide for livestock) well on less than 35 acres, but last time I checked state law (I actually found the law online one time) it stated 35 acres or more to drill a new well. For me, I'd want to be able to irrigate, water my yard, and provide at least my dogs and/or livestock, so a limited well wouldn't do.