If they don't have legal authority over well share agreements, then they would probably not regulate the number of well shares. However, I would recommend you contact them directly with your questions at http://www.azwater.gov. I've also included the link for the FAQ's for quick access:
Since you're from Scottsdale, I am assuming you might be referring to the Rio Verde Foothills area, where the most I've seen on one well is four shares.
Keller Williams Arizona Realty