Document ID: ./input/supremecourt_opinions/opinions/22pdf/21-454_4g15.pdf
Page Number: 48.0

14 

SACKETT v. EPA 

THOMAS, J., concurring 

the Federal Water Power Act for the construction of hydro-
electric dams in “navigable waters.”  311 U. S., at 406–410. 
Only after applying the Daniel Ball definition to determine 
that the river in question was navigable did the Court hold
that  Congress  had  plenary  authority  over  the  erection  of
structures in the river, regardless of whether the structure
actually  impeded  navigability.  311  U. S.,  at  423–426. 
While this represented an expansive application of the old 
concept that Congress can prevent obstructions to naviga-
ble capacity, see supra, at 4, 7–8, Appalachian Elec. made 
clear that the term “navigable waters” remained tethered to 
Congress’ traditional channels-of-commerce authority—not
to  the  broader  conceptions  of  the  commerce  authority
adopted by the Court at that time.

The next year, in Oklahoma ex rel. Phillips v. Guy F. At-
kinson Co., 313 U. S. 508 (1941), the Court reaffirmed that 
the term “navigable waters,” this time as used in the Flood 
Control  Act  of  1936,  was  to  be  interpreted  in  light  of  the
expanded Daniel Ball test.  313 U. S., at 522–525.  Signifi-
cantly,  Oklahoma  was  decided  mere  months  after  Darby, 
one of the most significant cases expanding the scope of the
commerce  authority.  312  U. S.,  at  119.    However,  Okla-
homa did not so much as mention Darby in construing the 
jurisdiction Congress conveyed in the term “navigable wa-
ters.”  Instead, it cited Darby only in passing and to support
the argument that, once a river is deemed navigable under 
the channels-of-commerce authority, Congress has author-
ity to protect “the nation’s arteries of commerce” by regulat-
ing  intrastate  activities  on  nonnavigable  parts  and  tribu-
taries  of  the  navigable  river  lest  such  activities  “impai[r] 
navigation itself.”  Oklahoma, 313 U. S., at 525.  This was 
nothing more than an application of the principle that Con-
gress can regulate activities that obstruct navigable capac-
ity.  Thus,  even  as  the  Court  expanded  the  Commerce 
Clause  in  other  contexts,  it  continued  to  understand  that 
the  term  “navigable  waters”  refers  solely  to  the  aquatic