may,  as  has  been  stated,  divert  and  use  the  water  for  the
purposes  of  his  mill,  provided  he  does  not  thereby  ia-
terfere  with  the  rights  of  other  riparian  owners  above  or
below  him.  He  cannot,  however,  unless  he  has  gained  a
prescriptive  right  to  do  so,  interfere,  by  his  user  of  the
water,  with  the  rights  of  other  riparian  owners.^

"  The  owner  on  the  banks  of  a  non-navigable  river,"
says  Lord  Blackburn,^  "  has  an  interest  in  having  the
'  water  above  him  flow  down  to  him,  and  in  having  the
'  water  below  him  flow  away  from  him  as  it  has  been
'  wont  to  do,  yet  I  apprehend  that  a  proprietor  may,
'  without  any  illegality,  build  a  mill-dam  across  the
'  stream  within  his  own  property,  and  divert  the  water
'  into  a  mill  lade  without  asking  leave  of  the  proprietors
'  above  him ;  provided  he  builds  it  at  a  place  so  much
'  below  the  lands  of  those  proprietors  as  not  to  obstruct
'  the  water  from  flowing  away  as  freely  as  it  was  wont,
'  and  without  asking  leave  of  the  proprietors  below  him,
'  if  he  takes  care  to  restore  the  water  to  its  natural  course
'  before  it  enters  their  land."

So  where  a  riparian  owner  has  so  appropriated  in  a
reasonable  manner  the  water  of  a  stream  to  a  beneficial
use,  he  may  at  once  maintain  an  action  for  any  infringe-
ment of  this  new  use  by  other  riparian  owners,  above  or
below  him.  He  cannot,  however,  unless  he  has  gained  a
prescriptive  right  so  to  do,  interfere  by  his  user  of  the
water  with  the  rights  of  other  riparian  owners.
