5101
 INT
United States
Environmental Protection
Agency
Office of Water
Regulations and Standards
Washington, DC 20460
 September 1980

810R80103
             Water
vvEPA     Intermittent Streams
             Water Quality Standards
             Criteria Summaries
             A Compilation
             of State/Federal Criteria

-------
          INTERMITTENT STREAMS
         Water Quality Standards
           Criteria Summaries
 A Compilation of State/Federal Criteria
             September 1980
  U. S. Environmental Protection Agency
Office of Water Regulations and Standards
        Washington, D. C.  20460
                     ,- .- V -, 3

-------
Protection  /u.

-------
                NATIONAL SUMMARY




                        OF




         STATE WATER QUALITY STANDARDS









              INTERMITTENT STREAMS




                PRO VISIQ NS/POLICIES






                 SEPTEMBER, 1980











                  PREPARED FOR




UNITED STATES ENVIRONMENTAL PROTECTION AGENCY




         CRITERIA AND STANDARDS DIVISION




                401 M STREET, S.  W.




              WASHINGTON, D. C.  20460
                   PREPARED BY




       NALESNIK ASSOCIATES INCORPORATED




             505 ELEVENTH STREET, S. E.




              WASHINGTON, D. C. 20003
                                 Contract Number   68-01-6058



                                 Project Number     WA-80-A055

-------
INTRODUCTION
This digest is compiled to provide general information to the public as well as to
Federal, State,  and  local  officials.   It  contains  excerpts from  the individual
Federal-State water quality standards establishing pollutant specific  criteria for
interstate surface waters.  The water quality standards program is implemented by
the  U.  S.  Environmental  Protection  Agency where  responsibility  for  providing
water quality recommendations,  approving State-adopted standards  for interstate
waters, evaluating adherence  to the standards, and  overseeing enforcement  of
standards compliance, has been mandated by Congress.

Standards,  a  nationwide strategy for  surface water quality management,  contain
three major  elements:  the use  (recreation, drinking water,  fish and  wildlife
propagation,  industrial,  or agricultural) to be made of  the navigable water;  criteria
to protect  these uses; and  an  antidegradation statement  to protect existing high
quality waters, from degradation  by the addition of pollutants.

Water  quality  criteria (numerical  or  narrative  specifications)   for  physical,
chemical, temperature,  and biological constituents are stated in the July 1976 U. S.
Environmental Protection Agency publication Quality Criteria for Water  (QCW),
available from the Government Printing Office, Washington, D. C. The 1976 QCW,
commonly  referred  to  as  the  "Red  Book," is  the most current compilation  of
scientific information used  by  the Agency as a  basis for assessing water  quality.
This publication is  subject  to periodic  updating and revisions  in  light  of new
scientific and technical  information.

Intermittent  streams provisions and policies in State  water quality  standards are
the subject of this  digest.   These provisions and policies  are  included into  the
standards when  a State  wishes  to qualify the applicability of its water criteria to
intermittently low flow  streams.  The Agency has recommended that water quality
standards should  protect  specified  uses of  a  waterway  in critical  low  flow
situations.*   Additionally,  for  intermittent streams,  the Agency  recommends
criteria be adopted to  that extent  necessary  to  assure  that  conditions  in  the
streams or stream beds  will not impair existing or designated uses in the stream or
in downstream  waters.   The Quality  Criteria for  Water  (1976)  recommends
pollutant criteria for the protection of aquatic life and other stream  uses during
the minimum stream flow,  which in many cases  is the average seven-day low flow
which occurs  once in ten years  (i.e.7Q10).

Since water  quality standards experience  revisions and upgrading  from time  to
time, following  procedures set  forth in the Clean Water  Act,  individual entries in
this  digest may  be superseded.  As these revisions  are accomplished and allowing
for the States to revise  their standards accordingly, this digest will be  updated and
reissued.  Because this  publication is not intended for use other than as a  general
*  Guidelines for State and Areawide Water Quality Management Program
Development; Chapter 5, Water Quality Standards.

-------
information resource, to obtain the latest information and for special purposes and
applications, the reader  needs to refer to  the  current approved  water  quality
standards.  These can be obtained from the State water pollution control agencies
or the EPA or Regional  Offices.

Individual State-adopted criteria follow:

-------
                          REFERENCES

A
     California Water Quality Standards by River Basins, c.a. 1975

     For  more detailed  information  on selected  basins,  sub-basins
     and  stretches  of streams and coastal areas refer to  California
     State Water Quality Standards.
15
     Delaware Water Quality Standards, March 25,  1979
r>
     Idaho Water Quality Standards, c.a. September, 1979

     Missouri Water Quality Standards, c.a. February, 1978

     American Samoa Water Quality Standards,
     Revised July, 1973

     Territory of Guam Water Quality Standards, Sept.  1975
s~*\
     Trust Territory of the Pacific Islands Water Quality
     Standards, October  21, 1973

H    Virgin Islands Water Quality Standards, Aug. 1973
ENVIRONMENT REPORTER, The Bureau of National Affairs, Inc.
Washington, D. C. 20037

1    Pages 701:0501-0509, February 16, 1979

2    Pages 706:1004-1008, July 20, 1979

3    Pages 711:0542-0544, August 5, 1977

4    Pages 716:0603, March  26, 1976

5    Pages 726:1005, 1011-1013, March 7, 1980

     Basic Water Quality Standards adopted May 22, 1979,
     have not yet been submitted to EPA for formal approval.

6    Pages 731:1002-1009, September  8, 1978

7    Pages 746:1008-1014, October 19, 1979

8    Pages 751:0504-0505, January 25, 1980

9    Pages 765:0512-0515, January 30, 1976

10   Page 761:0503-0504, 1973

-------
11   Page 766:0504-0509, October 5, 1979


12   Pages 771:0502-0504, September 29, 1978


13   Pages 776:0504-0506, April 10, 1979


14   Pages 781:0501-0502, May 18, 1979


15   Pages 786:0501-0502, August 29, 1975


16   Page 791:0583, May 26, 1978


17   Pages 796:0103-0108, February 16, 1979

1 8
     Pages 801:1001-1002, Sept. 29, 1978

1 q
     Page 806:1003, March 30, 1979

on
     Page 811:1043, 1974


21   Pages 816:0602-0607, 0642-0648, 1974

99
     Pages 821:0502-0505, June 30, 1978
00
     Pages 831:0501-0510, February 21, 1975

94
     Page 836:0502, June 30, 1978

OR
     Pages 841:0507-0537, December 7, 1979

9fi
     Pages 846:0501-0508, November 17, 1978

97
     Pages 851:1001-1023, December 15, 1978

98
     Pages 856:1001-1002, July 18, 1978

oq
     Pages 861:1002-1007, August 11, 1979

on
     Pages 866:1004-1009, December 28, 1979


31   Pages 871:0501-0506, November 25, 1977

QO
     Pages 876:1001-1043, May 26, 1978

3Q
     Pages 881:1001-1007, September 21, 1979

Q.4.
     Pages 886:0513-0524, August 29, 1975

QC
     Pages 891:1001-1129, November 16, 1979
                                     IV

-------
oc
     Pages 901:0501-0505, November 3, 1978

37   Pages 906:0501-0506, October 13, 1978

30
J    Pages 911:0501-0507, June 22, 1979
OQ
     Pages 916:0541-0544, April 14, 1978

40
     Pages 921:1001-1003, August 13,  1976

41   Pages 926:0541-0563, January 26, 1979

49
     Pages 931:0501-0508, May 26, 1978
A
-------
                           INTERMITTENT STREAMS
                             PROVISIONS/POLICIES
State
Alabama
Alaska
Arizona1
Arkansas
California
Agricultural   and  Industrial  Water  Supply,   Industrial
Operations.

This category includes watercourses  in which natural flow
is intermittent and non-existent during  droughts and  which
may,  of necessity, receive treated  wastes  from existing
municipalities and industries, both now and  in the future.
In such instances, recognition must be given  to the lack of
opportunity for mixture of the  treated  wastes with  the
receiving stream  for purposes of compliance.

Not Specified

When the entire  flow in a watercourse that would other-
wise be  dry  at that time and place  is  effluent  from  a
wastewater treatment  facility or agricultural  irrigation
return flow or combination thereof, the Council may, upon
application,   taking   into    consideration    R9-21-206,
R9-21-207, and R9-21-208,  determine that  all or part of
such  water  quality  standards  do not apply  where  the
Council finds that such entire flow does not present a sub-
stantial danger to the health of the public.

When a watercourse  that would otherwise be dry at  the
time  and  place  is  the subject  of  excavation or  other
activities in  connection with retrieval  of  sand, gravel, or
other  materials,  these water  quality standards shall  not
apply to waters entering such excavations from occassional
streamflows or to such waters discharged therefrom.

Ephemeral Streams - Where  there are streams with  inter-
mittent flow, the treatment of waste  discharged  thereto
shall be no less than conventional secondary or equivalent.

Stream Flows  -  These standards  are  based upon  the
assumption that  existing flow  conditions in  streams shall
continue without material  change.   The Water  Quality
Standards shall apply at all times except during  periods
when  flows are less than the average minimum 7-day  low
flow which occurs once in ten years.

Not Specified
                                      - 1-

-------
Colorado"
Connecticut
Delaware
       7
Florida
       o
Georgia
Hawaii
..  ,  10
Idaho

Illinois
         B
Indiana
       12
Iowa
     13
Low Flow Exceptions - Water quality standards shall apply
at all times except where surface waters are below mini-
mum annual average  seven-consecutive-day flow expected
to occur once in ten (10) years.  For certain substances,
such as ammonia, the low flow exceptions may be based on
the  seasonal  average  seven-consecutive-day  low  flow
expected to occur once in ten (10) years.  Each season will
normally consist of a minimum of three months.

The minimum average daily  flow for  seven consecutive
days that can be expected to occur once in ten years under
natural conditions is the  minimum flow  to which  the
standards apply except when a stream is regulated to result
in low flows below that level in which case the  standards
apply  to  the  absolute low  flow  resulting  from  such
regulation.

Not Specified

Not Specified

Specific criteria or standards set for the  various para-
meters apply  to  all  flows  on  regulated  streams.    On
unregulated streams,  they shall apply  to  all streamflows
equal to or exceedng to 7-day, 10-year minimum flow.

Not Specified

Not Specified

Except as otherwise provided  in this Chapter with  respect
to  temperature, the  water  quality standards in  this Part
shall apply at all  times except during periods when flows
are less than  the average  minimum seven  day  low flow
which occurs once in ten years.

All water quality standards in Section 6 of this Regulation,
except  those provided in subsection 6(a), will cease to be
applicable when  the stream  flows are less than the average
minimum  seven-consecutive-day  low  flow  which occurs
once in ten years. This determination will be made using
Low-Flow, Characteristics of Indiana Streams by  Paul  B.
Rohne, Jr., 1972, United States Department of the Interior,
Geological Survey, or  any additional information compiled
on a comparable basis.

Fish  and  aquatic life,  wildlife, secondary  recreation:
Chemical constituents shall not be exceeded at any time
the flow  equals or exceeds the seven-day,  ten-year flow
unless  the  material  is  from   uncontrollable  nonpoint
sources.
                                      - 2-

-------
Iowa  (con't)
                 Water quality standards shall be met at all times when the
                 flow of the receiving stream equals or  exceeds the average
                 seven-day  low  flow   which  occurs once  in  ten  years.
                 Exceptions may  be made for  intermittent  or low  flow
                 streams.   Where intermittent streams  are  classified for
                 Class B aquatic life protection the department may waive
                 the seven day, ten year low flow requirement and establish
                 a minimum  flow in lieu  thereof.   Such waiver  shall be
                 granted only when it has determined that aquatic resources
                 of the receiving waters are of no significance at flows less
                 than the established minimum.
Kansas
       14
Kentucky

Louisiana
      17
Maine
         15
16
Maryland
         18
For  class A waters, the applicable criteria listed  below
shall apply at all times.  For  class B streams, the  appli-
cable criteria listed below shall apply  at all times except
during periods when streamflows, including releases from
reservoirs, are less  than the average minimum seven-day
low flow which occurs once  in ten years,  or when stream
flow is less than 1 cfs, whichever value is greater. Quality
criteria shall be met insofar as is practicable when stream-
flows are less than those stipulated.

All watercourses which  reach zero natural flow annually
shall be exempted  from water use classification  and  the
application of the Specific Criteria, Section VII except the
following water courses which shall be classified as Class B
waters:  1) those waters  specifically  listed in  the State
Water  Quality Standards; and  2) those waters where evi-
dence  specifically   indicates  that  aquatic  life  will  be
supported because of pooling during periods of zero natural
flow.

Not Specified

Not Specified

Minimum  Flow  - Regulated  Rivers  and  Streams:   For
regulated  rivers  and   streams,  the  Department  may
establish  a  minimum  flow  necessary  to  maintain  water
quality  standards.  This flow will be based upon achieving
the assigned classification, criteria and protection of  the
uses of the  stream.  The Department will  cooperate with
appropriate  Federal, State  and private  interests  in  the
development   and   maintenance   of    stream   flow
requirements.

(1)   Discharges of effluent  to intermittent streams is  not
     permitted if feasible alternatives are available.

(2)   In  instances  where  discharge  to  an intermittent
     stream is permitted by the Administration, the dis-
     charge shall comply with Effluent Limitations (Regu-
     lation   08.05.04.05)  as  well  as  Receiving  Water
     Quality Standards (Regulation 08.05.04.03).
                                      - 3-

-------
Massachusetts
             19
Michigan
        20
Minnesota
         21
The  Division  will determine  the most severe hydrologic
condition at which water quality standards must be met.  In
classifying the inland waters of the Commonwealth and in
applying these standards  to such waters, the  critical low
flow condition at and above which these standards must  be
met  is the  average minimum consective seven day flow to
be expected once in ten years, unless otherwise stated  by
the Division in  these standards.  In artificially regulated
waters, the critical low  flow will  be established by  the
Division through  agreement  with the  Federal,  state  or
private interest controlling the flow.  The minimum flow
established in  such agreement will become the critical low
flow under this section for those waters covered by the
agreement.

Protection of  Low Flow  Waters;  Certain  waters will  be
designated by the Division in  Regulation  5.5  of  these
standards  for  protection under  this section  due to their
inability to accept pollutant discharges.  New or increased
discharges  of  pollutants to waters so designated are prohi-
bited unless   a  variance  is granted  by the  Division  as
provided in Regulation 4.6

The accepted  design streamflow to which the water quality
standards as prescribed by these rules shall apply are those
equal to or exceeding the ten-year recurrence of a mini-
mum low flow average of seven-day duration, except where
the commission  determines that a more restrictive applica-
tion  is necessary to protect a particular designated use.

Discharges of sewage,  industrial waste or  other  waste
effluents  shall  be controlled  so that  the water quality
standards  will be maintained at all stream flows which are
equal to or exceeded  by 90 percent of the seven  conse-
cutive daily average flows of record  (the lowest weekly
flow with a once  in ten year recurrence interval) for the
critical month(s).  The period of record for determining the
specific flow  for the  stated  recurrence interval,  where
records are available, shall include at least the most recent
ten years  of record, including  flow  records obtained after
establishment  of  flow  regulation devices, if any.   Such
calculations shall not be applied to lakes and  their embay-
ments which have noncomparable flow recurrence interval.
Where stream  flow records are not available, the flow may
be estimated  on the basis of available information on the
watershed  characteristics, precipitation, run-off and other
relevant data.

Allowance  shall not be made  in the design of treatment
works for low stream  flow  augmentation unless such flow
augmentation  of  minimum flow is dependable and  con-
trolled under applicable laws or regulations.
                                      - 4-

-------
          22
Mississippi
Missouri
       .D
Montana
        23
Nebraska
         24
All criteria contained herein shall apply to all stages  of
streamflow  greater  than   or  equal to  the  7-day,  10-year
minimum  flow in unregulated,  natural streams, and the
legally  guaranteed minimum  flow in  regulated  streams.
This requirement  shall not be  interpreted to permit any
unusual waste discharges during periods  of lower flow.

(A)  The  general  criteria shall  apply to all waters of the
state at all times.

(B)  The  specific  criteria  for each use shall apply to all
waters, however, the Commission will consider  exceptions
in the following cases:

     1. Exception will be considered  for streams when the
     flow is equal to or below the 7-day, once-in-ten-years
     low  flow.

     2.   Exceptions  will be considered in regulated-flow
     streams  if the flow falls below  the minimum release
     flow agreed upon by the regulating agencies.

     3.   Excpetions will be considered when  the effluent
     flow constitutes a majority of the  stream flow.

     4.  Exceptions will be considered when the stream  or
     lake is subjected  to non-point source pollutants due
     to storm water runoff.   The water quality  manage-
     ment process shall minimize the  adverse effects  of
     storm water  runoff.   Exceptions  during  storm water
     runoff shall  not be  construed  as license  to  relax
     point-source  controls.

     5.  Exceptions are granted  for the  unavoidable chemi-
     cal  and physical changes that occur  in the  hypolim-
     nion of lakes.  Release waters from dams shall meet
     specific criteria to protect downstream uses.

Streams that may cease flow in dry periods, but  maintain
permanent pools which support aquatic life are identified.

Until such time as minimum stream  flows  are established
for dewatered  streams,  the minimum  treatment require-
ments for discharges to dewatered receiving streams are  to
be  no  less  than  the minimum treatment requirements
prescribed.

Treatment  requirements  for discharges to  intermittent
streams are to be no less  than the minimum  treatment
requirements prescribed.

"The  Water  Quality Standards, except  general criteria
(Rule 2.(2), will not apply to: ...
                                      - 5-

-------
Nebraska  (con't)
Nevada
       25
New Hampshire
           27
New Jersey
           28
New Mexico
         9Q
New Yorl<

              30
North Carolina
(b) Waters during periods when the flow is less than 0.1 cfs,
or when the flow is less than the 7-day-10-year low flow.

(c)  Effluent  dominated streams during periods  when  the
daily flow is totally composed of effluent, excluding minor
amounts of bank seepage."

The  specified standards will not be  considered violated
when the natural conditions  of the receiving  water  are
outside  the established limits, including periods of extreme
high or  low flow.  Where effluents are discharged  to such
waters,  the discharges shall not be considered a contributor
to substandard conditions provided maximum  treatment in
compliance with permit requirements is maintained.

The water  quality standards shall apply at all times except
during periods when receiving stream  flows are less than
the minimum average ten-day flow which  occurs  once in
twenty years.

The  levels of  quality specified  for  various water  uses,
where  applicable, are expected to be  maintained under
conditions  comprising  minimum  consecutive   seven-day
fresh water flows with ten-year recurrence intervals.

The  Water  Quality  Standards  apply  at all  flows unless
specified otherwise.

Water Quality Standards apply at all times.

The  governing  flow  criterion for the  water  quality  stan-
dards excluding dissolved oxygen and toxics shall be  the
minimum average flow for a period of seven consecutive
days that has an average  recurrence of once in ten  years
(the seven  day ten year low flow).  The seven day ten year
low flow shall also be the governing flow for the dissolved
oxygen  water quality standards  during the  summer  dis-
charge period defined in 15 NCAC 2B.0404.  The governing
flow for toxic  water quality standards  shall be the  mini-
mum average flow for a period of 30 consecutive days that
has an  average recurrence of once in  two years. In  cases
where the stream flow is regulated,  the  governing flow for
all  water  quality  standards shall  be  the instantaneous
minimum flow or if deemed appropriate by the commission,
the minimum daily average flow.

These governing criteria  are established  specifically  for
setting  effluent  limitations  and for the design  of waste-
water treatment facilities.  In addition,  the governing flow
also established  a value below which deviations from water
quality  standards can be anticipated.
                                      - 6-

-------
North Dakota
             31
Ohio
    32
Oklahoma
         33
In the case of periods where the flow in the stream is less
than the 10-year, 7-day  low flow level,  the  Department
reserves the right to make a case-by-case evaluation  of
application of  these  standards.   However,  no substances
shall  be present  in  concentrations or combinations  that
materially interfere with, or that prove hazardous to, the
intended water usage.

Seasonal Warm water Habitat:   These   are  the waters
capable of supporting the  propagation and habitation  of
aquatic organisms on a seasonal basis.  These waters have a
minimum annual 7 day average flow that has a recurrence
period of once in  ten years (not attributable to discharges
and other hydraulic alterations) of 1 cubic foot per second
or less and having more than 50 per cent of the total flow
under such conditions composed of wastewater effluents.
Mixing zone standards, Rule 3745-1-06 of the Ohio Admini-
strative Code will not apply.

Limited Warmwater Habitat:  These are  waters incapable
of meeting  criteria necessary for the support of popula-
tions  of fish  and associated vertebrate  and  invertebrate
organisms and plants either on a  seasonal or  year around
basis.  This degraded condition may be due to  relative low
stream  flow coupled  with heavily populated and/or indus-
trialized areas that  have  outdated sewer systems  and/or
waste  treatment  facilities.   However,  exceptions   from
Warmwater  Habitat  criteria will apply   only  to specific
criterion during specified time periods and/or flow condi-
tions.  This will be determined on a case-by-case basis and
comply with all Federal and State water  quality  statutes.
This designation must be justified by significant economic
or technological rationale  and is to be  used only  as  a
temporary classification with upgrading of use designation
at the earliest possible time prior to July 1,  1983, where
attainable.

Standards for the support of this use designation will be the
same  as the standards for  the support of the use desig-
nation Warmwater Habitat.  However, individual  criterion
will be varied on  a case-by-case  basis and will supersede
the standards  for  other use designations where applicable.
The ammonia-N limit will correspond to the concentrations
in Table 2,  where applicable, but the most stringest  con-
centration to be met at any time will be  the  value set in
Section 3745-l-08(C)(l) of the Ohio Administrative Code.

The numerical and descriptive (i.e. bioassay related) limits
shall be maintained at all times and apply to all perennial
streams of the State with the exception of when the flow is
less  than the seven-day, two-year low flow  value.  For
intermittent streams, the numerical and descriptive limits
                                      - 7-

-------
Oklahoma
  (con't)
_      34
Oregon

Pennsylvania
Rhode Island
            36
              07
South Carolina
South Dakota
             38
shall be maintained  except when the flow is less than 1.0
cfs.  All other general standards shall be maintained at all
times and apply to all perennial and intermittent streams
of the State except when  conditions are attributable to
natural phenomena.

Not Specified

The  accepted  design  stream  flow,  to  which  the water
quality criteria as set  forth in this chapter shall apply, is
the  actual  or  estimated  lowest   seven-consecutive-day
average flow that occurs once in ten years for a stream
with unregulated flow, or the estimated minimum flow for
a stream  with  regulated flows, except where the Depart-
ment determines  that a  more restrictive  application is
necessary to protect a  particular  designated  or existing
use.  Where  the lowest seven-consecutive-day average  flow
that occurs once in ten years is zero, the Department shall
specify  the  design flow based  on  the identified or esti-
mated flow at that point where a use identified in section
93.4  of  this   title  (relating  to  statewide  water  uses)
becomes possible.

The  minimum  average daily  flow  for seven  consecutive
days that  can be expected  to occur once in ten years shall
be the minimum flow to which the standards apply.

Water Quality Testing -  For the purposes of these regula-
tions, water quality criteria will be determined under the
most adverse  conditions.   For water quality  parameters
most adverse  conditions  shall  mean  minimum  dilution
predictable  and complete  disruption in operation of  any
Waterwater  Treatment Facility.  Minimum dilution of  flow
shall be the minimum average daily flow for seven  con-
secutive  days  that can be  expected to  occur  once in ten
years. For other  water  quality parameters, most  adverse
conditions shall be  defined by the  director according to
sound engineering and scientific practices.  Bacteriological
surveys of sea water should include sampling during periods
when the  most  unfavorable  hydrographic  and pollution
conditions prevail.

Specific water quality standards are not applicable where
natural flow conditions are lower than those which occur at
the  minimum  seven-day average flow that  occurs with  a
frequency of once in ten  years.

Flow rates for high  quality waters:  When flow in  streams
classified for  the beneficial use of  cold water permanent
fish  life propagation, cold water marginal fish life propaga-
tion, or warm water permanent fish life propagation  falls
below the minimum seven day average flow that can be
                                      -8-

-------
South Dakota
  (con't)
Tennessee
         39
Texas
     40
Utah
    41
Vermont
        42
expected to occur once  in every twenty-five years, water
quality  criteria shall not  apply  to  the  water  but  any
applicable effluent regulations shall remain in force.

Flow rates for low quality fishery waters:  When the  flow
in streams classified for the beneficial use of warm water
semipermanent fish life propagation or warm water margi-
nal fish life propagation falls below the minimum seven day
average flow that can be expected to occur  once in every
five years but not less than 1.0 c.f.s., water quality criteria
shall not apply to  the water but any applicable effluent
regulations shall remain in force.

The criteria  set forth shall be applied on the basis of the
following stream flows:

Unregulated  streams    stream  flows equal  to  or greater
than the 3-day minimum, 20 year recurrence interval;

Regulated streams   all flows  in excess of the minimum
critical flow  occurring once  in 20 years as determined by
an  analysis of records  of operation and approved by the
Commissioner  of  the Tennessee Department  of  Public
Health.

The dissolved  oxygen concentrations represent minimum
values  and shall  apply at all  times  that the  daily  flow
exceeds the base flow condition.  The base flow condition
is defined as either the  7-day minimum average  flow for
the existing hydrologic conditions  with a recurrence inter-
val of two years or 0.1 cfs, whichever is higher.

Temperature: Same as dissolved oxygen.

Other  Parameters  and  General  Criteria:    The  general
criteria and  the numerical  criteria not specifically  dis-
cussed above shall apply at all times regardless  of  flow
unless specifically excepted.

Failure  of a stream to meet water quality standards when
stream flow is either  unusually high  or less than the 7-day,
10-year minimum flow shall not  be cause for  action against
persons discharging wastes which meet both the require-
ments of PART I of these regulations and the requirements
of applicable  permits.

Water   quality  classification  standards and  associated
requirements  shall  apply in all instances  except  during
periods  when the low natural stream flow is less than the
consecutive seven (7) day mean low flow with  a ten  (10)
year return period.  On those rivers and streams  whose rate
of  flow is artificially  regulated, the flow  shall not be
reduced to a point where these standards and  requirements
                                      -9-

-------
Vermont
  (con't)
Virginia

          44
Washington

            45
West Virginia
         46
Wisconsin
Wyoming
        47
American Samoa

District of  .
   Columbia
governing water quality cannot be met nor shall such flow
be regulated  in  such a  way  as to  produce  erosion or
sedimentation with resulting discoloration or  turbidity in
excess of the limits provided in these regulations.    The
Secretary shall cooperate with appropriate  federal, state,
municipal and private interests in  the development and
maintenance of streamflow requirements.

This  rule shall in no way be construed to permit less than
the normal design operation of  any  waste water treatment
facility during periods of low stream flow or  to otherwise
waive any discharge prohibitions or restrictions.

Not Specified

Not applicable.

Stream quality standards are to apply at all  times when
flows are equal to or  greater than the minimum  mean 7-
consecutive-day  drought   flow   with  a  10-year  return
frequency.

The  Standards shall apply at all times except (a)  during
periods when flows are less than the average minimum 7-
day low  flow  which occurs once in 10 years  (7-day Q10),
and (b) in channels  which convey a  treated  effluent to
natural surface waters. In determining the 7-day Q10 flow,
consideration  will be given to streams subject  to hydrau-
lically altered flow regimes.

Where stream flow data are availabe, these standards shall
apply at all times except during periods when flows are less
than the average of the  minimum seven consecutive day
flow which has  the  probability of occurring once  in ten
years.

During periods when stream flows are less  than the mini-
mums  described above   the  Wyoming  Game and  Fish
Department  and the  Department may  require  the  dis-
charger to institute operational  modifications  as necessary
to insure the  protection of aquatic life. Where stream flow
data are  not  available,  the Department must take  into
consideration  the possible existence of markedly abnormal
flows when determining violations of these standards.

Not Specified

The criteria assigned to a stream applies to  all flows equal
to or exceeding the 7-day, 10-year  minimum flow  except
where, and to the extent that,  natural conditions prevent
their attainment.
                                      -10-

-------
         TJ
   Guam                     Not Specified

   Puerto Rico               Water quality standards shall apply at all times, except for
                              surface waters  during periods when their flows  are  less
                              than  the  average  minimum  seven-day low  flow  which
                              occurs once in ten years.
                   /-i
   Trust Territories           Not Specified
                TT
   Virgin Islands              Not Specified
i>U.S. GOVERNMENT PRINTING OFFICE: 1980-341-082/106

-------

-------
United States
Environmental Protection
Agency
Washington DC 20460
Official Business
Penalty for Private Use $300
Postage and
Fee'  paid
Env.ronmental
Protection
Agency
EPA 335
                Third-Class

-------