Document ID: ./input/supremecourt_opinions/opinions/boundvolumes/558bv.pdf
Page Number: 433.0

272 

SOUTH  CAROLINA  v.  NORTH  CAROLINA 

Opinion of the Court 

uses,  the  availability  of  storage  water,  the  practical  ef­
fect  of  wasteful  uses  on  downstream  areas,  [and]  the 
damage  to  upstream  areas  as  compared  to  the  beneﬁts 
to  downstream  areas  if  a  limitation  is  imposed  on  the 
former.’ ”  Colorado v.  New Mexico, supra, at 183 (quot­
ing Nebraska v.  Wyoming, supra, at 618). 

In performing this task, there is no substitute for “ ‘the exer­
cise  of  an  informed  judgment,’ ”  Colorado  v.  New  Mexico, 
supra,  at 183,  and  we  will not  hesitate  to  seek out  the  most 
relevant information from the source best situated to provide 
it.  See  Maryland  v.  Louisiana,  451  U. S.,  at  745,  n.  21 
(allowing  intervention  of  private  pipeline  companies  “in  the 
interest of a full exposition of the issues”). 

With these considerations in mind, we turn to Duke Ener­
gy’s asserted interests.  Duke Energy operates 11 dams and 
reservoirs  in  both  States  that  generate  electricity  for  the 
region and control the ﬂow of the river.  The complaint itself 
acknowledges  the relationship  between  river ﬂow  and  Duke 
Energy’s operations, noting that a severe drought that ended 
in  2002  forced  Duke  Energy  to  “reduce  dramatically”  its 
hydroelectric  power  generation  from  the  Catawba  River. 
Complaint ¶ 17(c).  It is likely that any equitable apportion­
ment  of  the  river  will  need  to  take  into  account  the  amount 
of  water  that  Duke  Energy  needs  to  sustain  its  operations 
and  provide  electricity  to  the  region,  thus  giving  Duke  En­
ergy a strong interest in the outcome of this litigation.  See 
Colorado v.  New Mexico, supra, at 188 (noting the appropri­
ateness of considering “the balance of harm and beneﬁt that 
might  result”  from  a  State’s  proposed  diversion  of  a  river). 
There is, moreover, no other similarly situated entity on the 
Catawba  River,  setting  Duke  Energy’s  interests  apart  from 
the class of all other citizens of the States.  See New Jersey 
v.  New York, 345 U. S., at 373. 

Just as important, Duke Energy has a unique and compel­
ling  interest  in  protecting  the  terms  of  its  existing  FERC