Document ID: ./input/supremecourt_opinions/opinions/21pdf/143orig_1qm1.pdf
Page Number: 3.0

Cite as:  595 U. S. ____ (2021) 

3 

Syllabus 

in the context of the Middle Claiborne Aquifer.  To the contrary, Mis-
sissippi’s ownership approach would allow an upstream State to com-
pletely  cut  off  flow  to  a  downstream  one,  a  result  contrary  to  the 
Court’s equitable apportionment jurisprudence.  The Court’s decision 
in Tarrant Regional Water Dist. v. Herrmann, 569 U. S. 614, does not 
support Mississippi’s position.  Tarrant concerned whether one State 
could cross another’s boundaries to access a shared water resource un-
der  the  terms  of  an  interstate  compact.    The  Court  did  not  consider 
equitable apportionment, because the affected States had negotiated a
compact  that  determined  their  respective  rights  to  the  resource.    To 
the extent Tarrant stands for the broader proposition that one State
may not physically enter another to take water in the absence of an 
express agreement, that principle is not implicated here.  The parties
have stipulated all of Tennessee’s wells are drilled straight down and 
do not cross the Mississippi-Tennessee border.  While the origin of an
interstate water resource may be relevant to the terms of an equitable
apportionment,  that  feature  alone  cannot  place  the  resource  outside 
the  doctrine  itself.    Because  the  waters  contained  in  the  Middle 
Claiborne  Aquifer  are  subject  to  equitable  apportionment,  the  Court 
overrules Mississippi’s exceptions and adopts the Special Master’s rec-
ommendation to dismiss the bill of complaint.  Pp. 9–11.

(c)  Mississippi has neither sought leave to amend its complaint nor
tendered a proposed complaint seeking equitable apportionment.  The 
Court  does  not  address  whether  Mississippi  should  be  granted  such 
leave and sustains Tennessee’s objection to the Special Master’s rec-
ommendation to grant Mississippi leave to amend.  Pp. 11–12. 

Exceptions overruled in part and sustained in part, and case dismissed.

 ROBERTS, C. J., delivered the opinion for a unanimous Court.