Document ID: ./input/supremecourt_opinions/opinions/boundvolumes/558bv.pdf
Page Number: 422

Cite as: 558 U. S. 256 (2010) 

261 

Opinion of the Court 

This  negotiated  ﬁgure  may  prove  unattainable.  Accord­
ing to the complaint, natural conditions and periodic ﬂuctua­
tions  have  caused  the  Catawba  River’s  ﬂow  to  fall  below 
1,100 cubic feet per second.  Duke Energy, which generates 
hydroelectric  power  from  a  series  of  reservoirs  on  the  Ca­
tawba  River,  developed  a  model  to  estimate  the  river’s 
ﬂow  if  the  river  were  not  impounded.  Id.,  ¶¶ 8,  16.  The 
complaint notes that according to Duke Energy’s model, the 
Catawba  River—even  in  its  natural  state—often  would  not 
deliver  into  South  Carolina  a  minimum  average  daily  ﬂow 
of  1,100  cubic  feet  per  second.  Id.,  ¶ 16;  App.  to  Motion  of 
State  of  South  Carolina  for  Leave  To  File  Complaint,  Com­
plaint,  and  Brief  in  Support  of  its  Motion  for  Leave  To  File 
Complaint  18.  South  Carolina  contends  that  North  Caroli­
na’s  authorization  of  large  transfers  of  water  from  the  Ca­
tawba River basin has exacerbated these conditions. 

Shortly after we granted leave to ﬁle the complaint, two of 
the entities named in the complaint—the CRWSP and Duke 
Energy—ﬁled  motions  for  leave  to  intervene  as  parties. 
The CRWSP sought leave to intervene as a party-defendant, 
asserting  its  interest  as  a  “riparian  user  of  the  Catawba 
River”  and  claiming  that  this  interest  was  not  adequately 
represented  because  of  the  CRWSP’s  “interstate  nature.” 
Motion of CRWSP for Leave To Intervene and Brief in Sup­
port  of  Motion  8,  9.  Speciﬁcally,  the  CRWSP  noted  that  it 
is a bistate entity that is jointly owned and regulated by, and 
supplies water to, North Carolina’s Union County and South 
Carolina’s  Lancaster  County.  Id.,  at  9.  Duke  Energy 
sought  leave  to  intervene  and  ﬁle  an  answer,  asserting  an 
interest  as  the  operator  of  11  dams  and  reservoirs  on  the 
Catawba River that control the river’s ﬂow, as the holder of 
a  50-year  license 1  governing  Duke  Energy’s  hydroelectric 

1 The  license  was  issued  in  1958  to  Duke  Energy’s  predecessor  by  the 
Federal  Power  Commission,  a  predecessor  of  the  FERC.  For  conven­
ience, we will refer to Duke Energy’s “FERC license” herein.