Document ID: ./input/supremecourt_opinions/opinions/08pdf/07-588.pdf/07-588.pdf
Page Number: 16.0

Cite as:  556 U. S. ____ (2009) 

13 

Opinion of the Court 

context,  is  best  interpreted  as  limiting  agency  discretion. 
For the reasons discussed earlier, §1326(b)’s silence cannot
bear that interpretation. 

In  American  Textile,  the  Court  relied  in  part  on  a  stat-
ute’s  failure  to  mention  cost-benefit  analysis  in  holding 
that  the  relevant  agency  was  not  required  to  engage  in 
cost-benefit  analysis  in  setting  certain  health  and  safety 
standards.    452  U. S.,  at  510–512.    But  under  Chevron, 
that an agency is not required to do so does not mean that 
an agency is not permitted to do so. 

This extended consideration of the text of §1326(b), and 
comparison  of  that  with  the  text  and  statutory  factors 
applicable  to  four  parallel  provisions  of  the  Clean  Water
Act,  lead  us  to  the  conclusion  that  it  was  well  within  the 
bounds  of  reasonable  interpretation  for  the  EPA  to  con-
clude that cost-benefit analysis is not categorically forbid-
den.  Other arguments may be available to preclude such
a rigorous form of cost-benefit analysis as that which was 
prescribed  under  the  statute’s  former  BPT  standard, 
which  required  weighing  “the  total  cost  of  application  of 
technology” against “the . . . benefits to be achieved.”  See, 
supra, at 10.  But that question is not before us. 

In  the  Phase  II  requirements  challenged  here  the  EPA 
sought only to avoid extreme disparities between costs and 
benefits.  The agency limited variances from the Phase II
“national performance standards” to circumstances where
the  costs  are  “significantly  greater  than  the  benefits”  of 
compliance.  40  CFR  §125.94(a)(5)(ii).    In  defining  the 
“national  performance  standards”  themselves  the  EPA 
assumed  the  application  of  technologies  whose  benefits
“approach  those  estimated”  for  closed-cycle  cooling  sys-
tems  at  a  fraction  of  the  cost:  $389  million  per  year,  69
Fed. Reg. 41666, as compared with (1) at least $3.5 billion 
per year to operate compliant closed-cycle cooling systems, 
id.,  at  41605  (or  $1  billion  per  year  to  impose  similar 
requirements  on  a  subset  of  Phase  II  facilities,  id.,  at