[Code of Federal Regulations]
[Title 40, Volume 19]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR131.10]

[Page 374-375]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 131--WATER QUALITY STANDARDS--Table of Contents
 
           Subpart B--Establishment of Water Quality Standards
 
Sec. 131.10  Designation of uses.


    (a) Each State must specify appropriate water uses to be achieved 
and protected. The classification of the waters of the State must take 
into consideration the use and value of water for public water supplies, 
protection and propagation of fish, shellfish and wildlife, recreation 
in and on the water, agricultural, industrial, and other purposes 
including navigation. In no case shall a State adopt waste transport or 
waste assimilation as a designated use for any waters of the United 
States.
    (b) In designating uses of a water body and the appropriate criteria 
for those uses, the State shall take into consideration the water 
quality standards of downstream waters and shall ensure that its water 
quality standards provide for the attainment and maintenance of the 
water quality standards of downstream waters.
    (c) States may adopt sub-categories of a use and set the appropriate 
criteria to reflect varying needs of such sub-categories of uses, for 
instance, to differentiate between cold water and warm water fisheries.
    (d) At a minimum, uses are deemed attainable if they can be achieved 
by the imposition of effluent limits required under sections 301(b) and 
306 of the Act and cost-effective and reasonable best management 
practices for nonpoint source control.
    (e) Prior to adding or removing any use, or establishing sub-
categories of a use, the State shall provide notice and an opportunity 
for a public hearing under Sec. 131.20(b) of this regulation.
    (f) States may adopt seasonal uses as an alternative to 
reclassifying a water body or segment thereof to uses requiring less 
stringent water quality criteria. If seasonal uses are adopted, water 
quality criteria should be adjusted to reflect the seasonal uses, 
however, such criteria shall not preclude the attainment and maintenance 
of a more protective use in another season.
    (g) States may remove a designated use which is not an existing use, 
as defined in Sec. 131.3, or establish sub-categories of a use if the 
State can demonstrate that attaining the designated use is not feasible 
because:
    (1) Naturally occurring pollutant concentrations prevent the 
attainment of the use; or
    (2) Natural, ephemeral, intermittent or low flow conditions or water 
levels prevent the attainment of the use, unless these conditions may be 
compensated for by the discharge of sufficient volume of effluent 
discharges without violating State water conservation requirements to 
enable uses to be met; or
    (3) Human caused conditions or sources of pollution prevent the 
attainment of the use and cannot be remedied or would cause more 
environmental damage to correct than to leave in place; or
    (4) Dams, diversions or other types of hydrologic modifications 
preclude the attainment of the use, and it is not feasible to restore 
the water body to its original condition or to operate such modification 
in a way that would result in the attainment of the use; or

[[Page 375]]

    (5) Physical conditions related to the natural features of the water 
body, such as the lack of a proper substrate, cover, flow, depth, pools, 
riffles, and the like, unrelated to water quality, preclude attainment 
of aquatic life protection uses; or
    (6) Controls more stringent than those required by sections 301(b) 
and 306 of the Act would result in substantial and widespread economic 
and social impact.
    (h) States may not remove designated uses if:
    (1) They are existing uses, as defined in Sec. 131.3, unless a use 
requiring more stringent criteria is added; or
    (2) Such uses will be attained by implementing effluent limits 
required under sections 301(b) and 306 of the Act and by implementing 
cost-effective and reasonable best management practices for nonpoint 
source control.
    (i) Where existing water quality standards specify designated uses 
less than those which are presently being attained, the State shall 
revise its standards to reflect the uses actually being attained.
    (j) A State must conduct a use attainability analysis as described 
in Sec. 131.3(g) whenever:
    (1) The State designates or has designated uses that do not include 
the uses specified in section 101(a)(2) of the Act, or
    (2) The State wishes to remove a designated use that is specified in 
section 101(a)(2) of the Act or to adopt subcategories of uses specified 
in section 101(a)(2) of the Act which require less stringent criteria.
    (k) A State is not required to conduct a use attainability analysis 
under this regulation whenever designating uses which include those 
specified in section 101(a)(2) of the Act.