# Title 33.1 — Department of Environmental Quality

## Article 33.1-16 — Control, Prevention, and Abatement of Pollution of Surface Water

## Chapter 33.1-16-02.1 — Standards of Quality for Waters of the State

### § 33.1-16-02.1-01. Authority.

These rules are promulgated pursuant to North Dakota Century Code chapters 61-28 and 23.1-11;
specifically, sections 61-28-04 and 23.1-11-05, respectively.
History: Effective January 1, 2019.
General Authority: NDCC 61-28-04; S.L. 2017, ch. 199, § 1
Law Implemented: NDCC 23.1-11, 61-28; S.L. 2017, ch. 199, § 26
### § 33.1-16-02.1-02. Purpose.

1. The purposes of this chapter are to establish a system for classifying waters of the state;
provide standards of water quality for waters of the state; and protect existing and potential
beneficial uses of waters of the state.
2. The state and public policy is to maintain or improve, or both, the quality of the waters of the
state and to maintain and protect existing uses. Classifications and standards are established
for the protection of public health and environmental resources and for the enjoyment of these
waters, to ensure the propagation and well-being of resident fish, wildlife, and all biota
associated with, or dependent upon, these waters; and to safeguard social, economical, and
industrial development. Waters not being put to use shall be protected for all reasonable uses
for which these waters are suitable. All known and reasonable methods to control and prevent
pollution of the waters of this state are required, including improvement in quality of these
waters, when feasible.
a. The "quality of the waters" shall be the quality of record existing at the time the first
standards were established in 1967, or later records if these indicate an improved quality.
Waters with existing quality that is higher than established standards will be maintained
at the higher quality unless affirmatively demonstrated, after full satisfaction of the
intergovernmental coordination and public participation provisions of the continuing
planning process, that a change in quality is necessary to accommodate important social
or economic development in the area in which the waters are located. In allowing the
lowering of existing quality, the department shall assure that existing uses are fully
protected and that the highest statutory and regulatory requirements for all point sources
and cost-effective and reasonable best management practices for nonpoint sources are
achieved.
b. Waters of the state having unique or high-quality characteristics that may constitute an
outstanding state resource shall be maintained and protected.

c. Any public or private project or development which constitutes a source of pollution shall
provide the best degree of treatment as designated by the department in the North
Dakota pollutant discharge elimination system. If review of data and public input indicates
any detrimental water quality changes, appropriate actions will be taken by the
department following procedures approved by the environmental protection agency.
(North Dakota Antidegradation Implementation Procedure, Appendix IV.)
History: Effective January 1, 2019; amended effective January 1, 2024.
General Authority: NDCC 61-28-04; S.L. 2017, ch. 199, § 1
Law Implemented: NDCC 23.1-11, 61-28-04; S.L. 2017, ch. 199, § 26
### § 33.1-16-02.1-03. Applicability.

Nothing in this chapter may be construed to limit or interfere with the jurisdiction, duties, or
authorities of other North Dakota state agencies.
History: Effective January 1, 2019.
General Authority: NDCC 61-28-04; S.L. 2017, ch. 199, § 1
Law Implemented: NDCC 23.1-11, 61-28; S.L. 2017, ch. 199, § 26
### § 33.1-16-02.1-04. Definitions.

The terms used in this chapter have the same meaning as in North Dakota Century Code chapter
61-28, except:
1. "Acute standard" means the one-hour average concentration does not exceed the listed
concentration more than once every three years.
2. "Best management practices" are methods, measures, or procedures selected by the
department to control nonpoint source pollution. Best management practices include structural
and nonstructural measures and operation and maintenance procedures.
3. "Chronic standard" means the four-day average concentration does not exceed the listed
concentration more than once every three years.
4. "Consecutive thirty-day average" is the average of samples taken during any consecutive
thirty-day period. It is not a requirement for thirty consecutive daily samples.
5. "Department" means the department of environmental quality.
6. A standard defined as "dissolved" means the total quantity of a given material present in a
filtered water sample, regardless of the form or nature of its occurrence.
7. "Eutrophication" means the process of enrichment of rivers, streams, lakes, reservoirs, and
wetlands with nutrients needed to maintain primary production.
8. "Nutrients" mean the chemical elements, primarily nitrogen and phosphorus, which are critical
to the growth of aquatic plants and animals.
9. "Pollution" means such contamination, or other alteration of the physical, chemical, or
biological properties, of any waters of the state, including change in temperature, taste, color,
turbidity, or odor. Pollution includes discharge of any liquid, gaseous, solid, radioactive, or
other substance into any waters of the state that will or is likely to create a nuisance or render
such waters harmful, detrimental, or injurious to public health, safety, or welfare; domestic,
commercial, industrial, agricultural, recreational, or other legitimate beneficial uses; or
livestock, wild animals, birds, fish, or other aquatic biota.

10. "Site-specific standards" mean water quality criteria developed to reflect local environmental
conditions to protect the uses of a specific water body.
11. A standard defined as "total" means the entire quantity of a given material present in an
unfiltered water sample regardless of the form or nature of its occurrence. This includes both
dissolved and suspended forms of a substance, including the entire amount of the substance
present as a constituent of the particulate material. Total recoverable is the quantity of a given
material in an unfiltered aqueous sample following digestion by refluxing with hot dilute
mineral acid.
12. "Water usage". The best usage for the waters shall be those uses determined to be the most
consistent with present and potential uses in accordance with the economic and social
development of the area. Present principal best uses are those defined in subdivisions a, b, c,
d, and e. These are not to be construed to be the only possible usages.
a. Municipal and domestic water. Waters suitable for use as a source of water supply for
drinking and culinary purposes after treatment to a level approved by the department.
b. Fish and aquatic biota. Waters suitable for the propagation and support of fish and other
aquatic biota and waters that will not adversely affect wildlife in the area. Low flows or
natural physical and chemical conditions in some waters may limit their value for fish
propagation or aquatic biota.
c. Recreation. Primary recreational waters are suitable for recreation where direct body
contact is involved, such as bathing and swimming, and where secondary recreational
activities such as boating, fishing, and wading are involved. Natural high turbidities in
some waters and physical characteristics of banks and streambeds of many streams are
factors that limit their value for bathing.
d. Agricultural uses. Waters suitable for irrigation, stock watering, and other agricultural
uses, but not suitable for use as a source of domestic supply for the farm unless
satisfactory treatment is provided.
e. Industrial water. Waters suitable for industrial purposes, including food processing, after
treatment. Treatment may include that necessary for prevention of boiler scale and
corrosion.
History: Effective January 1, 2019; amended effective January 1, 2024.
General Authority: NDCC 61-28-04; S.L. 2017, ch. 199, § 1
Law Implemented: NDCC 23.1-11, 61-28; S.L. 2017, ch. 199, § 26
### § 33.1-16-02.1-05. Variances and compliance schedules.

Upon written application by the responsible discharger, the department finds that by reason of
substantial and widespread economic and social impacts the strict enforcement of state water quality
criteria is not feasible, the department can permit a variance to the water quality standard for the
affected segment. The department can set conditions and time limitations with the intent that progress
toward improvements in water quality will be made. This can include interim criteria which must be
reviewed at least once every three years. A variance will be granted only after fulfillment of the
approved requirements at 40 CFR section 131.14, including public participation requirements and
environmental protection agency approval. A variance will not preclude an existing use.
A North Dakota pollutant discharge elimination system permit may contain a schedule to return a
permittee to compliance with water quality based effluent limits consistent with federal and state
regulations. Compliance schedules in North Dakota pollutant discharge elimination system permits are
subject to the requirements of section 33.1-16-01-15 and cannot be issued for new discharges or
sources.

History: Effective January 1, 2019; amended effective January 1, 2024.
General Authority: NDCC 61-28-04; S.L. 2017, ch. 199, § 1
Law Implemented: NDCC 23.1-11, 61-28; S.L. 2017, ch. 199, § 26
### § 33.1-16-02.1-06. Severability.

The rules contained in this chapter are severable. If any rules, or part thereof, or the application of
such rules to any person or circumstance are declared invalid, that invalidity does not affect the validity
of any remaining portion of this chapter.
History: Effective January 1, 2019.
General Authority: NDCC 61-28-04; S.L. 2017, ch. 199, § 1
Law Implemented: NDCC 23.1-11, 61-28; S.L. 2017, ch. 199, § 26
### § 33.1-16-02.1-07. Classification of waters of the state.

General. Classification of waters of the state shall be used to maintain and protect the present and
future beneficial uses of these waters. Classification of waters of the state shall be made or changed
whenever new or additional data warrant the classification or a change of an existing classification.
History: Effective January 1, 2019.
General Authority: NDCC 61-28-04; S.L. 2017, ch. 199, § 1
Law Implemented: NDCC 23.1-11, 61-28; S.L. 2017, ch. 199, § 26
### § 33.1-16-02.1-08. General water quality standards.

1. Narrative standards.
a. The following minimum conditions are applicable to all waters of the state except for
class II ground waters. All waters of the state shall be:
(1) Free from substances attributable to municipal, industrial, or other discharges or
agricultural practices that will cause the formation of putrescent or otherwise
objectionable sludge deposits.
(2) Free from floating debris, oil, scum, and other floating materials attributable to
municipal, industrial, or other discharges or agricultural practices in sufficient
amounts to be unsightly or deleterious.
(3) Free from materials attributable to municipal, industrial, or other discharges or
agricultural practices producing color, odor, or other conditions to such a degree as
to create a nuisance or render any undesirable taste to fish flesh or, in any way,
make fish inedible.
(4) Free from substances attributable to municipal, industrial, or other discharges or
agricultural practices in concentrations or combinations which are toxic or harmful to
humans, animals, plants, or resident aquatic biota. For surface water, this standard
will be enforced in part through appropriate whole effluent toxicity requirements in
North Dakota pollutant discharge elimination system permits.
(5) Free from oil or grease residue attributable to wastewater, which causes a visible
film or sheen upon the waters or any discoloration of the surface of adjoining
shoreline or causes a sludge or emulsion to be deposited beneath the surface of the
water or upon the adjoining shorelines or prevents classified uses of such waters.
(6) Free from nutrients attributed to municipal, industrial, or other discharges or
agricultural practices, in concentrations or loadings which will cause accelerated

eutrophication resulting in the objectionable growth of aquatic vegetation or algae or
other impairments to the extent that it threatens public health or welfare or impairs
present or future beneficial uses.
b. There shall be no materials such as garbage, rubbish, offal, trash, cans, bottles, drums,
or any unwanted or discarded material disposed of into the waters of the state.
c. There shall be no disposal of livestock or domestic animals in waters of the state.
d. The department shall propose and submit to the state engineer the minimum streamflows
of major rivers in the state necessary to protect the public health and welfare. The
department's determination shall address the present and prospective future use of the
rivers for public water supplies, propagation of fish and aquatic life and wildlife,
recreational purposes, and agricultural, industrial, and other legitimate uses.
e. No discharge of pollutants, which alone or in combination with other substances, shall:
(1) Cause a public health hazard or injury to environmental resources;
(2) Impair existing or reasonable beneficial uses of the receiving waters; or
(3) Directly or indirectly cause concentrations of pollutants to exceed applicable
standards of the receiving waters.
f. If the department determines that site-specific criteria are necessary and appropriate for
the protection of designated uses, procedures described in the environmental protection
agency's Water Quality Standards Handbook 1994 or other defensible methods may be
utilized to determine maximum limits. Where natural chemical, physical, and biological
characteristics result in exceedances of the limits set forth in this section, the department
may derive site-specific criteria based on the natural background level or condition. All
available information shall be examined, and all possible sources of a contaminant will be
identified in determining the naturally occurring concentration. All site-specific criteria
shall be noticed for public comment and subjected to other applicable public participation
requirements prior to being adopted.
2. Narrative biological goal.
a. Goal. The biological condition of surface waters shall be similar to sites or water bodies
determined by the department to be regional reference sites.
b. Definitions.
(1) "Assemblage" means an association of aquatic organisms of similar taxonomic
classification living in the same area. Examples of assemblages include fish,
macroinvertebrates, algae, and vascular plants.
(2) "Aquatic organism" means any plant or animal which lives at least part of its life
cycle in water.
(3) "Biological condition" means the taxonomic composition, richness, and functional
organization of an assemblage of aquatic organisms at a site or within a water body.
(4) "Functional organization" means the number of species or abundance of organisms
within an assemblage which perform the same or similar ecological functions.
(5) "Metric" means an expression of biological community composition, richness, or
function which displays a predictable, measurable change in value along a gradient
of pollution or other anthropogenic disturbance.

(6) "Regional reference sites" are sites or water bodies which are determined by the
department to be representative of sites or water bodies of similar type (e.g.,
hydrology and ecoregion) and are least impaired with respect to habitat, water
quality, watershed land use, and riparian and biological condition.
(7) "Richness" means the absolute number of taxa in an assemblage at a site or within
a water body.
(8) "Taxonomic composition" means the identity and abundance of species or
taxonomic groupings within an assemblage at a site or within a water body.
c. Implementation. The intent of the state in adopting a narrative biological goal is solely to
provide an additional assessment method that can be used to identify impaired surface
waters. Regulatory or enforcement actions based solely on a narrative biological goal,
such as the development and enforcement of North Dakota pollutant discharge
elimination system permit limits, are not authorized. However, representative biological
assessment information may be used in combination with other information to assist in
determining whether designated uses are attained and to assist in determining whether
new or revised chemical-specific permit limitations may be needed. Implementation will
be based on the comparison of current biological conditions at a particular site to the
biological conditions deemed attainable based on regional reference sites. In
implementing a narrative biological goal, biological condition may be expressed through
an index composed of multiple metrics or through appropriate statistical procedures.
History: Effective January 1, 2019; amended effective July 1, 2021; January 1, 2024.
General Authority: NDCC 61-28-04; S.L. 2017, ch. 199, § 1
Law Implemented: NDCC 23.1-11, 61-28; S.L. 2017, ch. 199, § 26
### § 33.1-16-02.1-09. Surface water classifications, mixing zones, and numeric standards.

1. Surface water classifications. Procedures for the classifications of streams and lakes of the
state shall follow this subsection. Classifications of streams and lakes are listed in appendix I
and appendix II, respectively.
a. Class I streams. The quality of the waters in this class shall be suitable for the
propagation or protection, or both, of resident fish species and other aquatic biota and for
swimming, boating, and other water recreation. The quality of the waters shall be suitable
for irrigation, stock watering, and wildlife without injurious effects. After treatment
consisting of coagulation, settling, filtration, and chlorination, or equivalent treatment
processes, the water quality shall meet the bacteriological, physical, and chemical
requirements of the department for municipal or domestic use.
b. Class IA streams. The quality of the waters in this class shall be the same as the quality
of class I streams, except that where natural conditions exceed class I criteria for
municipal and domestic use, the availability of softening or other treatment methods may
be considered in determining whether ambient water quality meets the drinking water
requirements of the department.
The Sheyenne River from its headwaters to one-tenth mile downstream from Baldhill
Dam is not classified for municipal or domestic use.
c. Class II streams. The quality of the waters in this class shall be the same as the quality of
class I streams, except that additional treatment may be required to meet the drinking
water requirements of the department. Streams in this classification may be intermittent
in nature which would make these waters of limited value for beneficial uses such as
municipal water, fish life, irrigation, bathing, or swimming.

d. Class III streams. The quality of the waters in this class shall be suitable for agricultural
and industrial uses. Streams in this class generally have low average flows with
prolonged periods of no flow. During periods of no flow, they are of limited value for
recreation and fish and aquatic biota. The quality of these waters must be maintained to
protect secondary contact recreation uses (e.g., wading), fish and aquatic biota, and
wildlife uses.
e. Wetlands. These water bodies, including isolated ponds, sloughs, and marshes, are to be
considered waters of the state and will be protected under section 33.1-16-02.1-08.
f. Lakes and reservoirs. The type of fishery a lake or reservoir may be capable of
supporting is based on the lake's or reservoir's geophysical characteristics. The capability
of a lake or reservoir to support a fishery may be affected by seasonal or climatic
variability or other natural occurrences, which may alter the physical and chemical
characteristics of the lake or reservoir.
Class Characteristics
1 Cold water fishery. Waters capable of supporting growth of cold water fish
species (e.g., salmonids) and associated aquatic biota.
2 Cool water fishery. Waters capable of supporting natural reproduction and
growth of cool water fishes (e.g., northern pike and walleye) and associated
aquatic biota. These waters are also capable of supporting the growth and
marginal survival of cold water species and associated biota.
3 Warm water fishery. Waters capable of supporting natural reproduction and
growth of warm water fishes (e.g., largemouth bass and bluegill) and
associated aquatic biota. Some cool water species may also be present.
4 Marginal fishery. Waters capable of supporting a fishery on a short-term or
seasonal basis (generally a "put and take" fishery).
5 Not capable of supporting a fishery due to high salinity.
2. Mixing zones. North Dakota mixing zone and dilution policy is contained in appendix III.
3. Numeric standards.
a. Class I streams. The physical and chemical criteria for class I streams are listed in
table 1 and table 2.
b. Class IA streams. The physical and chemical criteria shall be those for class I streams,
with the exceptions for chloride, percent sodium, and sulfate as listed in table 1.
c. Site-specific sulfate standard. The physical and chemical criteria for the Sheyenne River
from its headwaters to one-tenth of a mile downstream from Baldhill Dam shall be those
for class IA streams, with the exception of sulfate as listed in table 1.
d. Class II streams. The physical and chemical criteria shall be those for class IA, with the
chloride and pH and sulfates as listed in table 1.
e. Class III streams. The physical and chemical criteria shall be those for class II, with the
exceptions for sulfate as listed in table 1.
f. Wetlands, including isolated ponds, class 4 lakes not listed in appendix II, sloughs and
marshes. The physical and chemical criteria shall be those for class III streams, with
exceptions for temperature, dissolved oxygen as listed in paragraph 6 of subdivision g,

and other conditions not attributable to municipal, industrial, domestic, or agricultural
sources.
g. Lakes and reservoirs.
(1) The physical and chemical criteria for class I streams shall apply to all classified
lakes or reservoirs listed in appendix II.
(2) In addition, a guideline for use as a goal in any lake or reservoir improvement or
maintenance program is a growing season (April through November) average
chlorophyll-a concentration of twenty µg/l.
(3) The temperature standard for class I streams does not apply to Nelson Lake in
Oliver County. The temperature of any discharge to Nelson Lake shall not have an
adverse effect on fish, aquatic biota, recreation, and wildlife.
(4) A numeric temperature standard of not greater than fifty-nine degrees Fahrenheit
[15 degrees Celsius] shall be maintained in the hypolimnion of class I lakes and
reservoirs during periods of thermal stratification.
(5) The numeric dissolved oxygen standard of five mg/l as a daily minimum does not
apply to the hypolimnion of class III and IV lakes and reservoirs during periods of
thermal stratification.
(6) The numeric dissolved oxygen standard of five mg/l as a daily minimum and the
maximum temperature of eighty-five degrees Fahrenheit [29.44 degrees Celsius]
shall not apply to wetlands and class 4 lakes.
(7) Lake Sakakawea must maintain a minimum volume of water of five hundred
thousand-acre feet [61,674-hectare meters] that has a temperature of fifty-nine
degrees Fahrenheit [15 degrees Celsius] or less and a dissolved oxygen
concentration of not less than five mg/l.
History: Effective January 1, 2019; amended effective July 1, 2021; January 1, 2024.
General Authority: NDCC 61-28-04; S.L. 2017, ch. 199, § 1
Law Implemented: NDCC 23.1-11, 61-28; S.L. 2017, ch. 199, § 26

Substance or
Characteristic
(a = aquatic life)
(b = municipal &
domestic drinking
water)
(c = agricultural,
irrigation, industrial)
CAS1 No. (d = recreation) Maximum Limit
7429905 Aluminum2 (a) Acute Standard
750 micrograms per liter (µg/l)
Chronic Standard
87 µg/l
Where the pH is equal to or greater than 7.0, and the hardness is
equal to or greater than 50 mg/l as CaCO in the receiving water
after mixing, the 87 µg/l chronic total recoverable aluminum
criterion will not apply, and aluminum will be regulated based on
compliance with the 750 µg/l acute total recoverable aluminum
criterion.
N) (a) The one-hour average concentration of total ammonia as nitrogen
in mg/l does not exceed, more often than once every three years
on the average, the numerical value given by the following:
Where Oncorhynchus are absent; or
Where Oncorhynchus are present

Chronic Standard
The 30-day rolling average concentration of total ammonia as
nitrogen expressed in mg/l is not to exceed, more than once every
three years on average, the chronic criteria magnitude calculated
using the following formula:
In addition, the highest four-day average within the 30-day
averaging period should not be more than 2.5 times the criteria
more than once in three years on average.
c)
Class IA: 175 mg/l (30-day arithmetic average)
Class II and Class III: 250 mg/l (30-day arithmetic average)
(Total) (a)
Chronic: 0.011 mg/l
None Cylindrospermopsin 15 µ/l For Clean Water Act water quality criterion, no more than
(d) 3 excursions (10-day assessment periods) within a single
recreational season in a single year.
None Microcystins (d) 8 µ/l For Clean Water Act water quality criterion, no more than
3 excursions (10-day assessment periods) within a single
recreational season in a single year.
(a) collected during any 3-year period may be less than this value
provided that lethal conditions are avoided)
None E. coli4 (d) Not to exceed 126 organisms per 100 ml as a geometric mean of
representative samples collected during any 30-day consecutive
period, nor shall more than 10 percent of samples collected during
any 30-day consecutive period individually exceed 409 organisms
per 100 ml. For assessment purposes, the 30-day consecutive
period shall follow the calendar month. This standard shall apply
only during the recreation season May 1 to September 30.
None pH (a) Class I and IA: 6.5 - 9.0 (up to 10% of representative samples
collected during any 3-year period may exceed this range,
provided that lethal conditions are avoided).
Class II and Class III: 6.0 - 9.0 (up to 10% of representative

samples collected during any 3-year period may exceed this
range, provided that lethal conditions are avoided).
Flesh5 (a) Whole Body: 8.5 mg/kg Dry Weight
Muscle: 11.3 mg/kg Dry Weight
(mEq/l)
Class IA, II, and III: 60 percent of total cations as mEq/l
SO ) (b)
4 Class IA and II: 450 mg/l (30-day arithmetic average)
Class III: 750 mg/l (30-day arithmetic average)
Sulfates (Total as Site Specific: 750 mg/l (maximum) applies to the Sheyenne River
SO ) (a, b) from its headwaters to 0.1 mile downstream from Baldhill Dam
131.10(b) requirement: The water quality standards for the Red
River and the portions of the Sheyenne River located downstream
from the segment of the Sheyenne River to which the site-specific
sulfate standard applies must continue to be maintained. The
Sheyenne River from 0.1 mile downstream from Baldhill Dam to
the confluence with the Red River shall not exceed 450 mg/l
sulfate (total) 30-day arithmetic average, and the Red River shall
not exceed 250 mg/l sulfate (total) 30-day arithmetic average after
mixing downstream from the confluence of the Sheyenne River.
Regulated pollution control efforts must be developed to achieve
compliance with these water quality standards.
None Temperature (a) Eighty-five degrees Fahrenheit [29.44 degrees Celsius]. The
maximum increase shall not be greater than five degrees
Fahrenheit [2.78 degrees Celsius] above natural background
conditions.
None Combined radium 5 pCi/l (30-day arithmetic average)
226 and radium 228
(Total) (b)
None Gross alpha particle 15 pCi/l (30-day arithmetic average)
activity, including
radium 226, but
excluding radon and
uranium (b)
1 CAS No. is the chemical abstract service registry number. The registry database contains records
for specific substances identified by the chemical abstract service.
2 The US EPA 2018 recommended national criteria (304(a) criteria) for aluminum can be used for
site-specific chronic and acute criteria when appropriate and data is available. The criteria is based
upon multiple linear regression (MLR) models for fish and invertebrate species. Data requirements
are pH, DOC, and total hardness to quantify the effects of these water chemistry parameters on the
bioavailability and associated toxicity of aluminum to aquatic organisms.
3 The standard for nitrates (N) is intended as benchmark concentration when stream or lake specific

data is insufficient to determine the concentration that will cause excessive plant growth
(eutrophication). However, in no case shall the concentration for nitrate plus nitrite N exceed 10 mg/l
for any waters used as a municipal or domestic drinking water supply.
4 Where the E. Coli criteria are exceeded and there are natural sources, the criteria may be
considered attained, provided there is reasonable basis for concluding that the indicator bacteria
density attributable to anthropogenic sources is consistent with the level of water quality required by
the criteria. This may be the situation, for example, in headwater streams that are minimally affected
by anthropogenic activities.
5 Fish tissue elements are expressed as steady-state instantaneous measurement not to exceed the
criteria in the table. When fish egg/ovary concentrations are measured, the egg/ovary criterion
element supersedes any whole-body, or muscle criterion element. The fish flesh values in Table 1
and the water column criteria in Table 2 are independently applicable. Water column criterion
elements that are derived site-specifically using an empirical bioaccumulation factor approach or a
bioaccumulation mechanistic model approach, once duly established under the provisions of
40 CFR 131 will supersede the criteria in Table 2 and will be subordinate to fish tissue criterion
elements when both fish and water concentrations are measured. Any site-specific water column
criterion element established under the provisions of 40 CFR 131 is the applicable criterion in the
absence of fish tissue measurement, or in waters with new discharges of selenium where steady
state has not been achieved between water and fish tissue at the site.

Aquatic Life Value Human Health
Classes I, IA, II, III Value
Classes Class
CAS No. Pollutant (Compounds) Acute Chronic I, IA, II2 III3
(cis and trans isomers)
(Hexachlorocyclohexane-gamma)

(1,2-Benzanthracene)
(3,4-Benzopyrene)
(3,4-Benzofluoranthene)
(11,12-Benzofluoranthene)
(1,2,5,6-Dibenzanthracene)

Halocetic acids14 607

Aquatic Life Value Human Health
Classes I, IA, II, III Value
Classes Class
CAS No. Pollutant (Elements) Acute Chronic I, IA, II2 III3
1 Except for the aquatic life values for metals, the values given in this appendix refer to the total (dissolved plus suspended) amount of
each substance unless otherwise noted. For the aquatic life values for metals, the values refer to the total recoverable method for
ambient metals analyses.
2 Based on two routes of exposure - ingestion of contaminated aquatic organisms and drinking water.
3 Based on one route of exposure - ingestion of contaminated aquatic organisms only.
4 Substance classified as a carcinogen, with the value based on an incremental risk of one additional instance of cancer in one million
persons.
5 Chemicals which are not individually classified as carcinogens but which are contained within a class of chemicals, with carcinogenicity
as the basis for the criteria derivation for that class of chemicals; an individual carcinogenicity assessment for these chemicals is
pending.
6 Hardness dependent criteria. Value given is an example based on a CaCO hardness of 400 mg/l. Criteria for each case must be
calculated using the following formula:
For the Criterion Maximum Concentration (CMC):
Cadmium CMC = e0.9789[ln (hardness)]-3.866
Chromium (III) CMC = e0.8190[ln (hardness)] + 3.7256
Copper CMC = e0.9422[ln (hardness)] - 1.7000
Lead CMC = e1.2730[ln (hardness)] - 1.4600
Nickel CMC = e0.8460[ln (hardness)] + 2.2550
Silver CMC = e1.7200[ln (hardness)] - 6.5900
Zinc CMC = e0.8473[ln (hardness)] + 0.8840
CMC = Criterion Maximum Concentration (acute exposure value)

The threshold value at or below which there should be no unacceptable effects to freshwater aquatic organisms and
their uses if the one-hour concentration does not exceed that CMC value more than once every three years on the
average.
For the Criterion Continuous Concentration (CCC):
Cadmium CCC = e0.7977[ln (hardness)]-3.909
Chromium (III) CCC = e0.8190[ln (hardness)] + 0.6848
Copper CCC = e0.8545[ln (hardness)] - 1.7020
Lead CCC = e1.2730[ln (hardness)] - 4.7050
Nickel CCC = e0.8460[ln (hardness)] + 0.0584
Silver No CCC criterion for silver
Zinc CCC = e0.8473[ln (hardness)] + 0.8840
CCC = Criterion Continuous Concentration (chronic exposure value)
The threshold value at or below which there should be no unacceptable effects to freshwater aquatic organisms and
their uses if the four-day concentration does not exceed that CCC value more than once every three years on the
average.
7 Safe Drinking Water Act (MCL).
8 Freshwater aquatic life criteria for pentachlorophenol are expressed as a function of pH. Values displayed in the table correspond to a
pH of 7.8 and are calculated as follows:
CMC =exp [1.005 (pH) - 4.869] CCC = exp [1.005 (pH) - 5.134]
9 This criterion applies to total arsenic.
10 This criterion applies to total PCBs (i.e., the sum of all congener or all isomer or homolog or Arochlor analyses).
11 This criterion applies to the sum of alpha-endosulfan and beta-endosulfan.
12 This criterion applies to DDT and its metabolites (i.e., the total concentration of DDT and its metabolites should not exceed this value).
13 The nonylphenol criteria address CAS numbers 84852-15-3 and 25154-52-3.
14 The criterion is for a total measurement of 5 haloacetic acids, dichloroacetic acid, trichloroacetic acid, monochloroacetic acid,
bromoacetic acid, and dibromoacetic acid.
15 Hardness values shall be no greater than 400 mg/l. For waters with hardness concentrations greater than 400 mg/l, the actual ambient
hardness may be used where a site-specific water effect ratio has been determined consistent with the environmental protection
agency's water effect ratio procedure.
16 The department will recognize the biotic ligand model as an appropriate tool for developing site-specific limits for copper as well as the
water-effects ratio (WER) method.
### § 33.1-16-02.1-10. Ground water classifications and standards.

1. Class I ground waters. Class I ground waters are those with a total dissolved solids
concentration of less than 10,000 mg/l. The minimum conditions described in subsection 1 of
section 33.1-16-02.1-08 apply. Class I ground waters are not exempt under the North Dakota
underground injection control program in section 33.1-25-01-05.
2. Class II ground waters. Class II ground waters are those with a total dissolved solids
concentration of 10,000 mg/l or greater. Class II ground waters are exempt under the North
Dakota underground injection control program in section 33.1-25-01-05.
History: Effective January 1, 2019; amended effective January 1, 2024.
General Authority: NDCC 61-28-04; S.L. 2017, ch. 199, § 1
Law Implemented: NDCC 61-28-04

### § 33.1-16-02.1-11. Discharge of wastes.

On-surface discharges. The following are general requirements for all waste discharges or
chemical additions:
1. No untreated domestic sewage shall be discharged into the waters of the state.
2. No untreated industrial wastes or other wastes which contain substances or organisms which
may endanger public health or degrade the water quality of water usage shall be discharged
into the waters of the state.
3. The department must be notified at least twenty days prior to the application of any herbicide
or pesticide to surface waters of the state for control of aquatic pests. Only certified
applicators are allowed to apply chemicals. The notification must include the following
information:
a. Chemical name and composition.
b. Map which identifies the area of application and aerial extent (e.g., acres or square feet).
c. A list of target species of aquatic biota the applicant desires to control.
d. The calculated concentration of the active ingredient in surface waters immediately after
application.
e. Name, address, and telephone number of the certified applicator.
4. Any spill or discharge of waste which causes or is likely to cause pollution of waters of the
state must be reported immediately. The owner, operator, or person responsible for a spill or
discharge must notify the department as soon as possible by telephoning 1-833-99SPILL (1-
833-997-7455) or on the website www.spill.nd.gov and provide all relevant information about
the spill. The owner or operator is required to:
a. Take immediate remedial measures appropriate for the severity of the spill;
b. Determine the extent of pollution to waters of the state;
c. Provide alternate water sources to water users impacted by the spill or accidental
discharge;
d. Provide on request any documents, reports, or other information relevant to the spill or
discharge; or
e. Any other actions necessary to comply with this chapter.
History: Effective January 1, 2019; amended effective July 1, 2021.
General Authority: NDCC 61-28-04; S.L. 2017, ch. 199, § 1
Law Implemented: NDCC 23.1-11, 61-28; S.L. 2017, ch. 199, § 26

The following intrastate and interstate streams are classified as the class of water quality which is to be
maintained in the specified stream or segments noted. All tributaries, minor or intermittently flowing
watercourse, unnamed creeks, or draws not specifically mentioned are classified as class III streams.
Missouri River, including Lake Sakakawea and Oahe Reservoir I
Yellowstone I
Little Muddy River near Williston II
White Earth River II
Little Missouri River II
Knife River II
Spring Creek IA
Square Butte Creek below Nelson Lake IA
Heart River IA
Green River IA
Antelope Creek II
Muddy Creek II
Apple Creek II
Cannonball River II
Cedar Creek II
Beaver Creek near Linton II
Grand River IA
Spring Creek II
Souris River IA
Des Lacs River II
Willow Creek II
Deep River III
Mauvais Coulee I
James River IA
Pipestem IA
Cottonwood Creek II
Beaver Creek II
Elm River II
Maple River II

Bois de Sioux I
Red River I
Wild Rice River II
Antelope Creek III
Sheyenne River (except as noted below) IA
Baldhill Creek II
Maple River II
Rush River III
Elm River II
Goose River IA
Turtle River II
Forest River II
North Branch of Forest River III
Park River II
North Branch III
South Branch II
Middle Branch III
Cart Creek III
Pembina River IA
Tongue River II
The Sheyenne River from its headwaters to 0.1 mile downstream from Baldhill Dam is not classified
for municipal or domestic use.

Lakes and reservoirs are classified according to the water characteristics which are to be maintained in
the specified lakes and reservoirs. The physical and chemical criteria for class I streams shall apply to
all classified lakes and reservoirs listed. For lakes and other lentic water bodies not listed, the physical
and chemical criteria designated for class III streams shall apply.
Adams Mirror Lake 3
Adams N. Lemmon Lake 1
Barnes Lake Ashtabula 3
Barnes Moon Lake 2
Barnes Clausen Springs 3
Benson Wood Lake 2
Benson Graves 3
Benson Reeves 3
Bottineau Lake Metigoshe 2
Bottineau Long Lake 2
Bottineau Pelican Lake 3
Bottineau Carbury Dam 2
Bottineau Cassidy Lake 4
Bottineau Strawberry Lake 2
Bowman Bowman-Haley Dam 3
Bowman Gascoyne Lake 3
Bowman Kalina Dam 3
Bowman Lutz Dam 2
Bowman Spring Lake 3
Burke Powers Lake 3
Burke Short Creek Dam 2
Burke Smishek Dam 2
Burke Northgate Dam 2
Burleigh McDowell Dam 3
Burleigh Mitchell Lake 3
Burleigh New Johns Lake 2
Cass Casselton Reservoir 3
Cass Brewer Lake 2
Cavalier Mt. Carmel Dam 2
Dickey Moores Lake 3

Dickey Pheasant Lake 3
Dickey Wilson Dam 3
Divide Baukol-Noonan Dam 2
Divide Baukol-Noonan East Mine 2
Pond
Divide Skjermo Dam 2
Dunn Lake Ilo 3
Eddy Battle Lake 3
Eddy Warsing Dam 3
Emmons Braddock Dam 3
Emmons Nieuwsma Dam 2
Emmons Rice Lake 3
Foster Juanita Lake 3
Golden Valley South Buffalo Gap Dam 4
Golden Valley Camel Hump Dam 1
Golden Valley Odland Dam 3
Grand Forks Fordville Dam 2
Grand Forks Kolding Dam 3
Grand Forks Larimore Dam 2
Grand Forks Niagara Dam 3
Grant Heart Butte Dam 2
(Lake Tschida)
Grant Niagara Dam 3
Grant Raleigh Reservoir 2
Grant Sheep Creek Dam 2
Griggs Carlson-Tande Dam 3
Griggs Red Willow Lake 2
Hettinger Blickensderfer Dam 2
Hettinger Castle Rock Dam 4
Hettinger Indian Creek 2
Hettinger Larson Lake 3
Hettinger Mott Watershed Dam 3
Kidder Alkaline Lake 2
Kidder Cherry Lake 3
Kidder Crystal Springs 3
Kidder Frettim Lake 2
Kidder George Lake 5

Kidder Horsehead Lake 2
Kidder Lake Isabel 3
Kidder Lake Josephine 2
Kidder Lake Williams 3
Kidder Round Lake 2
LaMoure Heinrich-Martin Dam 3
LaMoure Kalmbach Lake 3
LaMoure Kulm-Edgeley Dam 3
LaMoure Lake LaMoure 3
LaMoure Lehr Dam 3
LaMoure Limesand-Seefeldt Dam 3
LaMoure Schlecht-Thom Dam 3
LaMoure Schlecht-Weix Dam 3
Logan Beaver Lake 3
Logan Mundt Lake 3
Logan Rudolph Lake 3
McHenry Cottonwood Lake 3
McHenry George Lake 3
McHenry Round Lake 3
McHenry Buffalo Lodge Lake 3
McIntosh Blumhardt Dam 2
McIntosh Clear Lake 3
McIntosh Coldwater Lake 3
McIntosh Dry Lake 2
McIntosh Green Lake 2
McIntosh Lake Hoskins 3
McKenzie Arnegard Dam 4
McKenzie Leland Dam 2
McKenzie Sather Dam 2
McLean Brush Lake 3
McLean Crooked Lake 3
McLean Custer Mine Pond 2
McLean East Park Lake 2
McLean Lake Audubon 2
McLean Lake Brekken 2
McLean Lake Holmes 2

McLean Lightning Lake 1
McLean Long Lake 4
McLean Riverdale Spillway Lake 1
McLean Strawberry Lake 3
McLean West Park Lake 2
Mercer Harmony Lake 3
Morton Crown Butte Dam 3
Morton Danzig Dam 3
Morton Fish Creek Dam 1
Morton Harmon Lake 3
Morton Nygren Dam 2
Morton Sweetbriar Dam 2
Mountrail Clearwater Lake 3
Mountrail Stanley City Pond 3
Mountrail Stanley Reservoir 3
Mountrail White Earth Dam 2
Nelson McVille Dam 2
Nelson Tolna Dam 2
Nelson Whitman Dam 2
Oliver East Arroda Lake 2
Oliver Nelson Lake 3
Oliver West Arroda Lake 2
Pembina Renwick Dam 3
Pierce Balta Dam 3
Pierce Buffalo Lake 3
Ramsey Cavanaugh Lake 3
Ramsey Devils Lake 2
Ransom Dead Colt Creek Dam 3
Renville Lake Darling 2
Richland Lake Elsie 3
Richland Mooreton Pond 3
Rolette Belcourt Lake 2
Rolette Carpenter Lake 2
Rolette Dion Lake 2
Rolette Gordon Lake 2
Rolette Gravel Lake 2

Rolette Hooker Lake 2
Rolette Island Lake 3
Rolette Jensen Lake 3
Rolette School Section Lake 2
Rolette Upsilon Lake 2
Rolette Shutte Lake 2
Sargent Alkali Lake 3
Sargent Buffalo Lake 3
Sargent Lake Tewaukon 3
Sargent Silver Lake 3
Sargent Sprague Lake 3
Sheridan Hecker Lake 2
Sheridan South McClusky Lake 2
(Hoffer Lake)
Sioux Froelich Dam 2
Slope Cedar Lake 3
Slope Davis Dam 2
Slope Stewart Lake 3
Stark Belfield Pond 1
Stark Dickinson Dike 1
Stark Patterson Lake 3
Steele North Golden Lake 3
Steele North Tobiason Lake 3
Steele South Golden Lake 3
Stutsman Arrowwood Lake 4
Stutsman Bader Lake 3
Stutsman Barnes Lake 3
Stutsman Clark Lake 3
Stutsman Crystal Springs 3
Stutsman Hehn-Schaffer Lake 3
Stutsman Jamestown Reservoir 3
Stutsman Jim Lake 4
Stutsman Spiritwood Lake 3
Stutsman Pipestem Reservoir 3
Towner Armourdale Dam 2
Towner Bisbee Dam 2
Walsh Bylin Dam 3

Walsh Homme Dam 3
Walsh Matejcek Dam 3
Ward Hiddenwood Lake 3
Ward Makoti Lake 4
Ward North-Carlson Lake 3
Ward Rice Lake 3
Ward Velva Sportsmans Pond 1
Wells Harvey Dam 3
Wells Lake Hiawatha 4
(Sykeston Dam)
Williams Blacktail Dam 3
Williams Cottonwood Lake 3
Williams East Spring Lake Pond 3
Williams Epping-Springbrook Dam 3
Williams Iverson Dam 2
Williams Kettle Lake 2
Williams Kota-Ray Dam 1
Williams McCleod (Ray) Reservoir 3
Williams McGregor Dam 1
Williams Tioga Dam 3
Williams Trenton Lake 2
Williams West Spring Lake Pond 3
Burleigh, Emmons, Lake Oahe 1
Morton, Sioux
Dunn, McKenzie, Lake Sakakawea 1
McLean, Mercer,
Mountrail, Williams

This policy addresses how mixing and dilution of point source discharges with receiving waters will be
addressed in developing chemical-specific and whole effluent toxicity discharge limitations for point
source discharges. Depending upon site-specific mixing patterns and environmental concerns, some
pollutants/criteria may be allowed a mixing zone or dilution while others may not. In all cases, mixing
zone and dilution allowances shall be limited, as necessary, to protect the integrity of the receiving
water's ecosystem and designated uses.
Where dilution is available and the discharge does not mix at a near instantaneous and complete rate
with the receiving water (incomplete mixing), an appropriate mixing zone may be designated. In
addition, a mixing zone may only be designated if it is not possible to achieve chemical-specific
standards and whole effluent toxicity objectives at the end-of-pipe with no allowance for dilution. The
size and shape of a mixing zone will be determined on a case-by-case basis. At a maximum, mixing
zones for streams and rivers shall not exceed one-half the cross-sectional area or a length ten times
the stream width at critical low flows, whichever is more limiting. Also, at a maximum, mixing zones in
lakes shall not exceed five percent of lake surface area or two hundred feet in radius, whichever is
more limiting. Individual mixing zones may be limited or denied in consideration of designated
beneficial uses or presence of the following concerns in the area affected by the discharge:
1. There is the potential for bioaccumulation in fish tissues or wildlife.
2. The area is biologically important, such as fish spawning/nursery areas.
3. The pollutant of concern exhibits a low acute to chronic ratio.
4. There is a potential for human exposure to pollutants resulting from drinking water use or
recreational activities.
5. The effluent and resultant mixing zone results in an attraction of aquatic life to the effluent
plume.
6. The pollutant of concern is extremely toxic and persistent in the environment.
7. The mixing zone would prohibit a zone of passage for migrating fish or other species (including
access to tributaries).
8. There are cumulative effects of multiple discharges and their mixing zones.
Within the mixing zone designated for a particular pollutant, certain numeric water quality criteria for
that substance may not apply. However, all mixing zones shall meet the general conditions set forth in
section 33-16-02-08 of the state water quality standards.
While exceedances of acute chemical specific numeric standards are not allowed within the entire
mixing zone, a portion of the mixing zone (the zone of initial dilution or ZID) may exceed acute
chemical-specific numeric standards established for the protection of aquatic life. The ZID shall be
determined on a case-by-case basis where the statement of basis for the discharge permit includes a
rationale for concluding that a zone of initial dilution poses no unacceptable risks to aquatic life. Acute
whole effluent toxicity (WET) limits shall be achieved at the end-of-pipe with no allowance for a ZID.

An appropriate dilution allowance may be provided in calculating chemical-specific acute and chronic
and WET discharge limitations where: 1) the discharge is to a river or stream, 2) dilution is available at
low-flow conditions, and 3) available information is sufficient to reasonably conclude that there is near
instantaneous and complete mixing of the discharge with the receiving water (complete mixing). The
basis for concluding that such near instantaneous and complete mixing is occurring shall be
documented in the statement of basis for the North Dakota pollutant discharge elimination system
permit. In the case of field studies, the dilution allowance for continuous dischargers shall be based on
the critical low flow (or some portion of the critical low flow). The requirements and environmental
concerns identified in the paragraphs above may be considered in deciding the portion of the critical
low flow to provide as dilution. The following critical low flows shall be used for streams and effluents:
Stream Flows
Aquatic life, chronic 4-day, 3-year flow (biologically based*)**
Aquatic life, acute 1-day, 3-year flow (biologically based)
Human health Harmonic mean flow
(carcinogens)
Human health 4-day, 3-year flow (biologically based) or
(noncarcinogens) 1-day, 3-year flow (biologically based)
Effluent Flows
Aquatic life, chronic Mean daily flow
Aquatic life, acute Maximum daily flow
Human health (all) Mean daily flow
* Biologically based refers to the biologically based design flow method developed by the
environmental protection agency. It differs from the hydrologically based design flow method in that
it directly uses the averaging periods and frequencies specified in the aquatic life water quality
criteria for individual pollutants and whole effluents for determining design flows.
** A 30-day, 10-year flow (biologically based) can be used for ammonia or other chronic standard
with a 30-day averaging period.
For chemical-specific and chronic WET limits, an appropriate dilution allowance may also be provided
for certain minor publicly owned treatment works where allowing such dilution will pose insignificant
environmental risks. For acute WET limits, an allowance for dilution is authorized only where dilution is
available and mixing is complete.
For controlled discharges, such as lagoon facilities that discharge during high ambient flows, the
stream flow to be used in the mixing zone analysis should be the lowest statistical flow expected to
occur during the period of discharge.
Where a discharger has installed a diffuser in the receiving water, all or a portion of the critical low
stream flow may be provided as a dilution allowance. The determination shall depend on the diffuser
design and on the requirements and potential environmental concerns identified in the above
paragraphs. Where a diffuser is installed across the entire river/stream width (at critical low flow), it will
generally be presumed that near instantaneous and complete mixing is achieved and that providing the
entire critical low flow as dilution is appropriate.

Where dilution flow is not available at critical conditions (i.e., the water body is dry), the discharge limits
will be based on achieving applicable water quality criteria (i.e., narrative and numeric, chronic and
acute) at the end-of-pipe; neither a mixing zone or an allowance for dilution will be provided.
All mixing zone dilution assumptions are subject to review and revision as information on the nature
and impacts of the discharge becomes available (e.g., chemical or biological monitoring at the mixing
zone boundary). At a minimum, mixing zone and dilution decisions are subject to review and revision,
along with all other aspects of the discharge permit upon expiration of the permit.
For certain pollutants (e.g., ammonia, dissolved oxygen, metals) that may exhibit increased toxicity or
other effects on water quality after dilution and complete mixing is achieved, the waste load allocation
shall address such effects on water quality, as necessary, to fully protect designated and existing uses.
In other words, the point of compliance may be something other than the mixing zone boundary or the
point where complete mixing is achieved.
The discharge will be consistent with the Antidegradation Procedure.
This procedure describes how dilution and mixing of point source discharges with receiving waters will
be addressed in developing discharge limitations for point source discharges. For the purposes of this
procedure, a mixing zone is defined as a designated area or volume of water surrounding or
downstream of a point source discharge where the discharge is progressively diluted by the receiving
water and numerical water quality criteria may not apply. Based on site-specific considerations, such a
mixing zone may be designated in the context of an individual permit decision. Discharges may also be
provided an allowance for dilution where it is determined that the discharge mixes with the receiving
water in near instantaneous and complete fashion. Such mixing zones and allowances for dilution will
be granted on a parameter-by-parameter and criterion-by-criterion basis as necessary to fully protect
existing and designated uses.
The procedure to be followed is composed of six individual elements or steps. The relationship of the
six steps and an overview of the mixing zone/dilution procedure is shown in figure 1.
Step 1 - No dilution available during critical low-flow conditions
Where dilution flow is not available at critical low-flow conditions, discharge limitations will be based on
achieving applicable narrative and numeric water quality criteria at the end-of-pipe during critical
low-flow conditions.
Step 2 - Dilution categorically prohibited for wetland discharges
Permit limitations for discharges to a wetland shall be based on achieving all applicable water quality
criteria (i.e., narrative and numeric, chronic and acute) at end-of-pipe.
Step 3 - Procedure for certain minor publicly owned treatment works
Minor publicly owned treatment works that discharge to a lake or to a river/stream at a dilution greater
than a 50-to-1 ratio qualify for this procedure. Minor publicly owned treatment works with dilution ratios
less than a 50-to-1 ratio may also qualify (at the discretion of the permit writer) where it can be
adequately demonstrated that this procedure poses insignificant environmental risks. For the purposes
of this procedure, the river/stream dilution ratio is defined as the chronic low flow of the segment
upstream of the publicly owned treatment works discharge divided by the mean daily flow of the
publicly owned treatment works. For controlled discharges from lagoon facilities (discharging during
high flows), the river/stream dilution ratio is defined as the lowest upstream flow expected during the
period of discharge divided by the mean daily flow of the discharge.

For minor publicly owned treatment works that qualify for this procedure and discharge to lakes, the
allowance for dilution for chemical-specific and chronic WET limits will be determined on a
case-by-case basis. Dilution up to a 19-to-1 ratio (five percent effluent) may be provided.
For minor publicly owned treatment works that qualify for this procedure and discharge to a river/stream
segment, dilution up to the full chronic aquatic life, acute aquatic life, and human health critical flows
may be provided.
Step 4 - Site - specific risk considerations
Where allowing a mixing zone or a dilution allowance would pose unacceptable environmental risks,
the discharge limitations will be based on achieving applicable narrative and numeric water quality
criteria at the end-of-pipe. The existence of environmental risks may also be the basis for a site-specific
mixing zone or dilution allowance. Such risk determinations will be made on a case-by-case and
parameter-by-parameter basis. These decisions will take into account the designated and existing uses
and all relevant site-specific environmental concerns, including the following:
1. Bioaccumulation in fish tissues or wildlife.
2. Biologically important areas such as fish spawning areas.
3. Low acute to chronic ratio.
4. Potential human exposure to pollutants resulting from drinking water or recreational areas.
5. Attraction of aquatic life to the effluent plume.
6. Toxicity/persistence of the substance discharged.
7. Zone of passage for migrating fish or other species (including access to tributaries).
8. Cumulative effects of multiple discharges and mixing zones.
Step 5 - Complete mix procedures
For point source discharges to rivers/streams where available data are adequate to support a
conclusion that there is near instantaneous and complete mixing of the discharge with the receiving
water (complete mix) the full critical low flow or a portion thereof may be provided as dilution for
chemical-specific and WET limitations. Such determinations of complete mixing will be made on a
case-by-case basis using best professional judgement. Presence of an effluent diffuser that covers the
entire river/stream width at critical low flow will generally be assumed to provide complete mixing. Also,
where the mean daily flow of the discharge exceeds the chronic low stream flow of the receiving water,
complete mixing will generally be assumed. In addition, where the mean daily flow of the discharge is
less than or equal to the chronic low flow of the receiving water, it will generally be assumed that
complete mixing does not occur unless otherwise demonstrated by the permittee. Demonstrations for
complete mixing should be consistent with the study plan developed in cooperation with the
states/tribes and environmental protection agency region VIII. Near instantaneous and complete mixing
is defined as no more than a ten percent difference in bank-to-bank concentrations within a longitudinal
distance not greater than two river/stream widths. For controlled discharges (lagoon facilities), the test
of near instantaneous and complete mixing will be made using the expected rate of effluent discharge
and the lowest upstream flow expected to occur during the period of discharge.
The following critical low flows shall be applied for streams and effluents:
Stream Flows
Aquatic life, chronic 4-day, 3-year flow (biologically based*)**
Aquatic life, acute 1-day, 3-year flow (biologically based)

Human health (carcinogens) Harmonic mean flow
Human health (noncarcinogens) 4-day, 3-year flow (biologically based) or
1-day, 3-year flow (biologically based)
Effluent Flows
Aquatic life, chronic Mean daily flow
Aquatic life, acute Maximum daily flow
Human health (all) Mean daily flow
* Biologically based refers to the biologically based design flow method developed by the
environmental protection agency. It differs from the hydrologically based design flow method in that
it directly uses the averaging periods and frequencies specified in the aquatic life water quality
criteria for individual pollutants and whole effluents for determining design flows.
** A 30-day, 10-year flow (biologically based) can be used for ammonia or other chronic standard
with a 30-day averaging period.
Where complete mixing can be concluded and the environmental concerns identified in step 4 do not
justify denying dilution, but are nevertheless significant, some portion of the critical low flows identified
above may be provided as dilution. Such decisions will take site-specific environmental concerns into
account as necessary to ensure adequate protection of designated and existing uses.
Step 6 - Incomplete mix procedures
This step addresses point source discharges that exhibit incomplete mixing. Because acute WET limits
are achieved at the end-of-pipe in incomplete mix situations, this step provides mixing zone procedures
for chronic aquatic life, human health, and WET limits, and ZID procedures for acute chemical-specific
limits. Where a ZID is allowed for chemical limits, the size of the ZID shall be limited as follows:
Lakes: The ZID volume shall not exceed ten percent of the volume of the chronic mixing zone.
Rivers The ZID shall not exceed ten percent of the chronic mixing zone volume or flow, nor
and shall the ZID exceed a maximum downstream length of one hundred feet, whichever is
Streams: more restrictive.
The following provides guidelines for determining the amount of dilution available for dischargers that
exhibit incomplete mixing.
Default Method
This method addresses situations where information needed for modeling is not available or there
are concerns about potential environmental impacts of allowing a mixing zone. The default method
provides a conservative dilution allowance.
Stream/river dischargers: Dilution calculation which uses up to ten percent of the critical low flow
for chronic aquatic life limits or human health limits. However, this allowance may be adjusted
downward on a case-by-case basis depending upon relevant site-specific information, designed
and existing uses of the segment, and especially the uses of the segment portion affected by the
discharge.
Lake/reservoir dischargers: Dilution up to a 4-to-1 ratio (twenty percent effluent) may be provided
for chronic aquatic life analyses or human health analyses. However, this allowance may be
adjusted downward on a case-by-case basis depending upon discharge flow, lake size, lake

flushing potential, designated and existing uses of the lake, and uses of the lake portion affected by
the discharge.
Modeling Method
An appropriate mixing zone model is used to calculate the dilution flow that will allow mixing zone
limits to be achieved at the critical low flow. Prior to initiating modeling studies, it should be
determined that compliance with criteria at the end-of-pipe is not practicable.
Field Study Method
Field studies which document the actual mixing characteristics in the receiving water are used to
determine the dilution flow that will allow mixing zone size limits to be achieved at the critical low
flow. For the purposes of field studies, "near instantaneous and complete mixing" is operationally
defined as no more than a ten percent difference in bank-to-bank concentrations within a
longitudinal distance not greater than two stream/river widths.


This antidegradation implementation procedure delineates the process that will be followed by
the department of environmental quality for implementing the antidegradation policy found in
Standards of Quality for Waters of the State, chapter 33.1-16-02.1.
Under this implementation procedure, all waters of the state are afforded one of three different
levels of antidegradation protection. All existing uses, and the water quality necessary for
those uses, shall be maintained and protected. Antidegradation requirements are necessary
whenever a regulated activity is proposed that may have some effect on water quality.
Regulated actions include permits issued under sections 402 (North Dakota pollutant
discharge elimination system) and 404 (dredge and fill) of the Clean Water Act, and any other
activity requiring section 401 water quality certification. Nonpoint sources of pollution are not
included. When reviewing section 404 nationwide permits, the department will issue
section 401 certifications only where it determines that the conditions imposed by such
permits are expected to result in attainment of the applicable water quality standards,
including the antidegradation requirements. However, it is anticipated that the department will
exclude certain nationwide permits from the antidegradation procedures for category 1 waters
on the basis that the category of activities covered by the permit is not expected to have
significant permanent effects on the quality and beneficial uses of those waters, or the effects
will be appropriately minimized and temporary.
Existing use means a use that was attained in the water body on or after 1967, whether or not
it is included in the water quality standards. This procedure presumes that attainment of the
criteria assigned to protect the current water body classification will serve to maintain and
protect all existing uses. However, where an existing use has water quality requirements that
are clearly defined, but are not addressed by the current classification and criteria, the
department will ensure that such existing uses are protected fully, based on implementation of
appropriate numeric or narrative water quality criteria or criteria guidance. In some cases,
water quality may have improved in the segment since the classification was assigned,
resulting in attainment of a higher use. In other cases, the classification may have been
assigned based on inadequate information, resulting in a classification that does not describe
or adequately protect actual uses of the segment. In such cases, the department will develop
requirements necessary to protect the existing uses and, where appropriate, recommend
reclassification of the segment.
The department will complete an antidegradation review for all proposed regulated activities.
The findings of these reviews will be summarized using an antidegradation worksheet. A
statement of basis for all conclusions will be attached to the completed worksheet. The level of
detail of the review will depend upon the antidegradation protection applicable to the various
classes of water.
In conducting an antidegradation review, the division of water quality will sequentially apply
the following steps:
A. Determine which level of antidegradation applies.

B. Determine whether authorizing the proposed regulated activity is consistent with
antidegradation requirements.
C. Review existing water quality data and other information submitted by the project
applicant.
D. Determine if additional information or assessment is necessary to make a decision.
E. A preliminary decision is made by the department and subsequently distributed for public
participation and intergovernmental coordination.
• The content of public notices will be determined case by case. In preparing a public
notice, the department may address: a) the department's preliminary
antidegradation review conclusions; b) a request for public input on particular
aspects of the antidegradation review that might be improved based on public input
(e.g., existing uses of a segment that needs to be protected); c) notice of the
availability of the antidegradation review worksheet; d) notice of the availability of
general information regarding the state antidegradation program; and e) a reference
to the state antidegradation policy.
• The antidegradation review findings will be available for public comment; however,
publication of a separate notice for purposes of antidegradation is not necessary.
For example, the antidegradation preliminary findings may be included in the public
notice issued for purposes of a North Dakota pollutant discharge elimination system
permit or Clean Water Act section 401 certification.
The department will ensure appropriate intergovernmental coordination on all
antidegradation reviews. At a minimum, the department will provide copies of the
completed antidegradation review worksheet and/or the public notice to appropriate local,
state, and federal government agencies, along with a written request to provide
comments by the public comment deadline.
F. Comments are considered.
G. The department determines if the change in quality is necessary to accommodate
important economic or social development.
H. The department makes a final decision.
The level of antidegradation protection afforded each water body in the state is consistent with
beneficial uses of those water bodies. Appendix I and appendix II of the Standards of Quality
for Waters of the State identify rivers, streams, and lakes in the state with their classification.
The classification shall be consistent with the following categories:
Category 1: Very high level of protection that automatically applies to class I and class IA
streams and class I, II, and III lakes, and wetlands that are functioning at their optimal level. In
addition, category 1 is presumed to apply to class II and class III streams. Particular class II
and class III streams may be excluded from category 1 if, at the time of the antidegradation
review, it is determined that one or both of the following criteria are applicable: 1) there is no
remaining assimilative capacity for any of the parameters that may potentially be affected by
the proposed regulated activity in the segment in question, or 2) an evaluation submitted by
the project applicant demonstrates (based on adequate and representative chemical, physical,
and biological data) that aquatic life and primary contact recreation uses are not currently
being attained because of stressors that will require a long-term effort to remedy. Evaluations
in response to criterion #2 must include more than an identification of current water quality
levels. They must include evidence of the current status of the aquatic life and primary contact
recreation uses of the segment.

Category 2: Class 4 and class 5 lakes and particular wetlands after antidegradation review. In
addition, class II and class III streams or wetlands meeting one of the criteria identified above
at the time of the antidegradation review shall be included in category 2.
Category 3: Highest level of protection; outstanding state resource waters.
Procedures for Category 1 Waters
Regulated activities that result in a new or expanded source of pollutants to this category of water
are subject to the review process, unless the source would have no significant permanent effect on
the quality and beneficial uses of those waters, or if the effects will be appropriately minimized and
temporary.
• Proposed activities that would lower the ambient quality in a water body of any parameter by
more than fifteen percent, reduce the available assimilative capacity by more than fifteen
percent, or increase permitted pollutant loadings to a water body by more than fifteen percent
will be deemed to have significant effects.
• The department will identify and eliminate from further review those proposed activities that
will have no significant effect on water quality or beneficial uses. Category 1 reviews will be
conducted where significant effects are projected for one or more water quality parameters.
Findings of significant effects may be based on the following factors: a) percent change in
ambient concentrations predicted at the appropriate conditions; b) percent change in loadings
for the individual discharge or to the segment from all discharges; c) reduction in available
assimilative capacity; d) nature, persistence, and potential effects of the parameter;
e) potential for cumulative effects; f) predicted impacts to aquatic biota; and g) degree of
confidence in any modeling techniques utilized.
• The applicant may be required to provide available monitoring data or other information about
the affected water body and/or proposed activity to help determine the significance of the
proposed degradation for specific parameters. The information includes recent ambient
chemical, physical, or biological monitoring data sufficient to characterize, during the
appropriate conditions, the spatial and temporal variability of existing background quality of
the segment for the parameters that would be affected by the proposed activity. The
information would also describe the water quality that would result if the proposed activity
were authorized.
The project applicant is required to provide an evaluation of the water quality effects of the project.
This evaluation may consist of the following components:
1. Pollution prevention measures.
2. Reduction in scale of the project.
3. Water recycle or reuse.
4. Process changes.
5. Alternative treatment technology.
6. Advanced treatment technology.
7. Seasonal or controlled discharge options to avoid critical water quality periods.
8. Improved operation and maintenance of existing facilities.
9. Alternative discharge locations.

The primary emphasis of the category 1 reviews will be to determine whether reasonable
nondegrading or less-degrading alternatives to the proposed degradation are available. The
department will first evaluate any alternatives analysis submitted by the applicant for adherence to
the minimum requirements described below. If an acceptable analysis of alternatives was
completed and submitted to the department as part of the initial project proposal, no further
evaluation of alternatives will be required of the applicant. If an acceptable alternatives analysis has
not been completed, the department will work with the project applicant to ensure that an
acceptable alternatives analysis is developed.
Once the department has determined that feasible alternatives to allowing the degradation have
been adequately evaluated, the department shall make a preliminary determination regarding
whether reasonable nondegrading or less-degrading alternatives are available. This determination
will be based primarily on the alternatives analysis developed by the project applicant, but may be
supplemented with other information or data. As a rule-of-thumb, nondegrading or less-degrading
pollution control alternatives with costs that are similar to the costs of the applicant's favored
alternative shall be considered reasonable. If the department determines that reasonable
alternatives to allowing the degradation do not exist, the department shall continue with the
antidegradation review and document the basis for the preliminary determination.
If the department makes a preliminary determination that one or more reasonable alternatives exist,
the department will work with the applicant to revise the project design. If a mutually acceptable
resolution cannot be reached, the department will document the alternative analysis findings and
provide public notice of a preliminary decision to deny the activity.
Although it is recognized that any activity resulting in a discharge to surface waters may have
positive and negative aspects, the applicant must show that any discharge or increased discharge
will be of economic or social importance in the area. Where there are existing regulated sources
located in the area, the department will assure that those sources are complying with applicable
requirements prior to authorizing the proposed regulated activity. New sources of a particular
parameter will not be allowed where there are existing unresolved compliance problems (involving
the same parameter) in the zone of influence of the proposed activity. The "zone of influence" is
determined as appropriate for the parameter of concern, the characteristics of the receiving water
body (e.g., lake versus river, etc.), and other relevant factors. Where available, a total maximum
daily load analysis or other watershed-scale plan will be the basis for identifying the appropriate
zone of influence. The department may conclude that such compliance has not been achieved
where existing sources are violating their North Dakota pollutant discharge elimination system
permit limits. However, the existence of a compliance schedule in the North Dakota pollutant
discharge elimination system permit may be taken into consideration in such cases. Required
controls on existing regulated sources need not be finally achieved prior to authorizing a proposed
activity provided there is reasonable assurance of future compliance.
Procedures for Category 2 Waters
Regulated activities that result in a permanent or temporary, new or expanded source of pollution to
this category of water are permitted if the following conditions are met:
1. The classified uses of the water would be maintained.
2. The assimilative capacity of the water is available for the parameters that would be
affected by the regulated activity, and existing uses would be protected as discussed in
section II.
A decision will be made on a case-by-case basis, using available data and best professional
judgment. The applicant may be required to provide additional information necessary for the
department to characterize or otherwise predict changes to the physical, chemical, and/or biological
condition of the water.

Procedures for Category 3 Waters
Outstanding state resource waters - Eligibility. Outstanding state resource waters may be
designated category 3 waters only after they have been determined to have exceptional value for
present or prospective future use for public water supplies, propagation of fish or aquatic life,
wildlife, recreational purposes, or agricultural, industrial, or other legitimate beneficial uses. The
factors that may be considered in determining whether a water body is eligible for inclusion in
category 3 include the following: a) location, b) previous special designations, c) existing water
quality, d) physical characteristics, e) ecological value, and f) recreational value.
Nomination. Any person may nominate any waters of the state for designation as outstanding
state resource waters. The nomination must be made in writing to the department, must describe
its specific location and present uses, and must state the reasons why the resource has
exceptional value for present or prospective future beneficial use.
Review process. The department with cooperation of the state water commission shall review any
nomination to determine whether the nominated waters of the state are eligible, clearly defined, and
identify beneficial uses of exceptional value for present or prospective future use. The department
of environmental quality with cooperation of the state water commission shall provide as a part of
its assessment: 1) a verification of the uses, properties, and attributes that define the proposed
"exceptional" value; 2) an evaluation of the current and historical condition of the water with respect
to the proposed value using the best data available; and 3) an estimate of likely regulatory
measures needed to achieve the desired level of protection. If the identified waters of the state are
eligible, clearly defined, and appear to identify beneficial uses of exceptional value for present or
prospective future use, the department, and the state water commission will solicit public comment
and/or hold a public hearing regarding the nomination. After reviewing the public comments and
views, the department jointly with the state water commission will make a decision on whether to
designate the defined water body as an outstanding state water resource. If both the department
and the state water commission agree that the defined water body should be designated as an
outstanding state water resource, the department shall submit the recommendation to the
department of environmental quality advisory council as part of the water quality standard revision
process. The designation, if made, may be reviewed on a periodic basis.
Implementation process. Effects on category 3 waters resulting from regulated activity will be
determined by appropriate evaluation and assessment techniques and best professional judgment.
Any proposed regulated activity that would result in a new or expanded source of pollutants to a
segment located in or upstream of a category 3 segment will be allowed only if there are
appropriate restrictions to maintain and protect existing water quality. Reductions in water quality
may be allowed only if they are temporary and negligible. Factors that may be considered in
judging whether the quality of a category 3 water would be affected include: a) percent change in
ambient concentrations predicted at the appropriate critical conditions; b) percent change in
loadings; c) percent reduction in available assimilative capacity; d) nature, persistence, and
potential effects of the parameter; e) potential for cumulative effects; and f) degree of confidence in
any modeling techniques utilized.
