Document ID: ./input/supremecourt_opinions/opinions/22pdf/21-1484_aplc.pdf
Page Number: 8

Cite as:  599 U. S. ____ (2023) 

5 

Opinion of the Court 

the  Little  Colorado,  and  the  San  Juan—border  the 
reservation.  To  meet  their  water  needs  for  household, 
agricultural,  industrial,  and  commercial  purposes,  the 
Navajos  obtain  water  from  rivers,  tributaries,  springs, 
lakes, and aquifers on the reservation. 

Much  of  the  western  United  States  is  arid.  Water  has 
long been scarce, and the problem is getting worse.  From 
2000  through  2022,  the  region  faced  the  driest  23-year
period in more than a century and one of the driest periods
in  the  last  1,200  years.    And  the  situation  is  expected  to 
grow  more  severe  in  future  years.    So  even  though  the
Navajo Reservation encompasses numerous water sources
and the Tribe has the right to use needed water from those
sources, the Navajos face the same water scarcity problem
that many in the western United States face. 

Over  the  decades,  the  Federal  Government  has  taken 
various steps to assist the people in the western States with 
their water needs.  The Solicitor General explains that, for 
the Navajo Tribe in particular, the Federal Government has
secured  hundreds  of  thousands  of  acre-feet  of  water  and 
authorized billions of dollars for water infrastructure on the 
Navajo Reservation.  See Tr. of Oral Arg. 5; see also, e.g., 
Consolidated  Appropriations  Act,  2021,  Pub.  L.  116–260,
134  Stat.  3227,  3230;  Northwestern  New  Mexico  Rural 
Water Projects Act, §§10402, 10609, 10701, 123 Stat. 1372,
1395–1397; Central Arizona Project Settlement Act of 2004, 
§104,  118  Stat.  3487;  Colorado  Ute  Settlement  Act 
Amendments  of  2000,  114  Stat.  2763A–261,  2763A–263; 
Act of June 13, 1962, 76 Stat. 96; Act of Apr. 19, 1950, 64
Stat. 44–45. 

In the Navajos’ view, however, those efforts did not fully
satisfy  the  United  States’s  obligations  under  the  1868 
treaty.  The Navajos therefore sued the U. S. Department 
of  the  Interior,  the  Bureau  of  Indian  Affairs,  and  other 
federal  parties.    As  relevant  here,  the  Navajos  asserted  a
breach-of-trust  claim  arising  out  of  the  1868  treaty  and