Section 15-2107. General duties

1.  Upon  its  organization  the  board  may  prepare  a  plan for the
  regulation of the flow of the river or rivers in its district. Such plan
  shall show the available and feasibile reservoir sites on such river  or
  rivers, whether any reservoir now existing can be and should be enlarged
  and to what extent, the approximate number of acres of land flowed or to
  be  flowed  by  each reservoir, whether any of such land is owned by the
  state and if any, how many acres, the number of acres  of  private  land
  required,  together  with  the estimated value of the land, and how many
  acres, if any, of such land are lands of the  state  within  the  forest
  preserve.  Such  acreage shall include such quantity of land surrounding
  the reservoir to be created or enlarged as would in the judgment of  the
  board  be required for the protection, maintenance and operation of such
  reservoir. The plan shall be accompanied  by  such  maps,  profiles  and
  other  data  and  descriptions as may be necessary to set forth properly
  the location and character of the work and of the property to  be  taken
  or  damaged,  and  by  estimates of cost of each such reservoir. In case
  maps, plans and specifications for any such reservoir  at  or  near  the
  site  thereof,  are on file in the office of the department, and in case
  any records in any other department of the state government would be  an
  aid  in  the  preparation of such plans, these shall be available to the
  board for such purpose.
    2. Upon the completion of such plan if the board approves of such plan
  it shall certify  it  to  the  department  for  its  approval,  and  the
  department  within forty days thereafter may approve the same, or modify
  it and approve it as so modified. As so approved by  the  department  it
  shall  be known as the "official plan" for the regulation of the flow of
  the river or rivers of the district. Copies thereof shall  be  filed  in
  the  offices  of  the  board, the department, and of the county clerk of
  each county wholly or partly within the  district.  Such  plan  in  like
  manner  may  be altered from time to time provided such alteration shall
  not affect any assessment already made.