Section 15-1521. Supply of water to other public water supply systems

On  any  application for a new or additional water supply or source of
  water supply, the department may require or authorize any  applicant  to
  make  provisions  for  the supply and to supply water to any area of the
  state which as determined by the department  in  its  decision  on  that
  application  properly  should  be supplied with water from the source or
  sources of water supply sought by the applicant. The owner  or  operator
  of  any  existing  or  proposed  water works system within such area may
  apply to the department for a permit to take water from that  source  of
  water  supply  or  from  any  part  of  the  water  supply system of the
  applicant supplied in  whole  or  in  part  from  that  source.  If  the
  department  so  requires, or if it grants a permit, it shall be the duty
  of the applicant so to supply water, subject to such requirements as the
  department may impose. The amount of water so to be taken and the  price
  to  be  paid  therefor  may be agreed upon between the applicant and the
  taker of the water, or if they cannot agree, fair and reasonable amounts
  and rates shall be, after due hearings thereon, fixed by the department,
  provided however, that such department shall have no power to fix  rates
  in  any  case  where  the  Public Service Commission has such power, and
  provided further, that  nothing  in  this  section  contained  shall  be
  construed as diminishing the powers of said Public Service Commission in
  respect  to  rates of water works companies subject to its jurisdiction.
  Any such agreement or determination of the department may from  time  to
  time  be  modified  by  further  agreement  between the parties affected
  thereby or by the further order of the department.