ยง 2900. Compensation; eminent domain taking. When property of a public
  benefit  corporation  is  taken  in the exercise of the power of eminent
  domain for a purpose substantially different from that for which  it  is
  held by such public benefit corporation, just compensation to the public
  benefit corporation shall be made in the same manner, to the same extent
  and subject to the same limitations as though it were private property.