Neb. Admin. Code tit. 117 — Department of Environment and Energy

Chapter 1 Definition of Terms

Neb. Admin. Code tit. 117, ch. 1 Definition of Terms {#sec-117-nac-1 omnilex-key=us-ne-regs-official--title-117--117 NAC 1}

001 The following terms are defined in Neb. Rev. Stat. §81-1502: Department, Garbage, Junk, Point Source, Refuse, Rubbish, and Water Pollution.

002 “Acute Criteria” means the threshold concentration of a substance that aquatic organisms can be exposed to for a period of 96 hours or less with no resulting acute toxicity.

003 “Acute Mixing Zone” means the limited area or volume of a waterbody, as designated by the Department, which adjoins a point source discharge, where acute criteria may be exceeded while wastewaters which have received the applicable level of treatment or control are allowed to assimilate, disperse, dissipate, or undergo chemical transformation.

004 “Acute Toxicity” means the response of an aquatic organism to a concentration of a substance which results in injury or mortality within a period of 96 hours or less.

005 “Acute Toxic Units (TUa)” means the reciprocal of the effluent dilution that causes an acute effect (e.g., LC50) to the test organism by the end of the acute exposure period.

006 “Applicable Level of Treatment or Control” means that treatment or control which is required by Title 119 - Rules and Regulations Pertaining to the Issuance of Permits under the National Pollutant Discharge Elimination System; Title 120 - Procedures Pursuant to Section 401 of the Federal Clean Water Act, 33 U.S.C. § 1251 Et Seq., for Certification by the Department of Activities Requiring a Federal License or Permit which may Result in a Discharge; or which is otherwise specified by the Department considering best available technology and management practices.

007 “Beneficial Use” means any productive use of surface waters for which water quality is protected. Beneficial uses include but are not limited to agricultural, industrial, and public water supplies; support and propagation of fish, and other aquatic life; recreation in and on the water; and aesthetics. Waste assimilation, disposal, or transport are not beneficial uses.

008 “Bioassay” means a test used to evaluate the relative toxicity of a substance by comparing its effect on a living organism to the effect of a standard preparation (control) on the same type of organism.

009 “Canal” means an artificial waterway constructed for the purpose of developing water power, or any other useful purpose, and from which water can be taken for irrigation.

010 “Chronic Criteria” means the threshold concentration of a substance that aquatic organisms can be exposed to for a period exceeding 96 hours with no resulting chronic toxicity.

011 “Chronic Mixing Zone” means the limited area or volume of a waterbody, as designated by the Department, which adjoins a point source discharge, where chronic criteria may be exceeded while wastewaters which have received the applicable level of treatment or control are allowed to assimilate, disperse, dissipate, or undergo chemical transformation.

012 “Chronic Toxicity” means the response of an aquatic organism to a concentration of a substance which results in adverse effects such as injury, mortality, reduced growth, or impaired reproduction after period of exposure exceeding 96 hours.

013 “Chronic Toxic Units (TUc)” means the reciprocal of the effluent dilution that causes no chronic toxicity to the test organisms by the end of the chronic exposure period.

014 “Clean Water Act” is the federal law codified at 33 U.S.C. §1251 et seq.

015 “Colloidal Substances” means clay or other substances which do not settle out of suspension in water without the use of a flocculent.

016 “Conductivity” means a measure of the ability of water to conduct an electrical current which is expressed in micromhos per centimeter. Conductivity is related to the number and types of chemical ions or dissolved solids in solution.

017 “Cubic Foot per Second (cfs)” means the unit of measurement used in reporting stream discharge, sometimes referred to as second-foot (sec-ft). It is a volume of one cubic foot passing a given point during one second of time and is equivalent to 7.48 gallons per second or 448.8 gallons per minute.

018 “Daily Mean” means an average of at least two appropriately spaced measurements, as determined by the Department, calculated over a period of one day. In calculating the daily mean for dissolved oxygen, values used in the calculations shall not exceed the dissolved oxygen air saturation value. If a measured value exceeds the dissolved oxygen air saturation value, then the dissolved oxygen air saturation value shall be used in calculating the daily mean.

019 “Dissolved Oxygen (DO)” means a measure of the amount of free oxygen in the water.

020 “Dissolved Oxygen Air Saturation Value” means the concentration of dissolved oxygen which represents 100 percent saturation at any given point in a water body based on the water temperature and atmospheric pressure.

021 “EPA” means the United States Environmental Protection Agency.

022 “Early-Life Stages” means all embryonic and larval stages and all juvenile forms of aquatic life to 30 days following hatching.

023 “Effluent” means wastewater, excluding sludge, discharging from a wastewater treatment works.

024 “Endangered Species” are identified by the Nebraska Game and Parks Commission in NAC Title 163, Chapter 4.

025 “Epilimnion” means the warm, freely circulating upper layer of thermally stratified lakes.

026 “Existing Uses” means those beneficial uses actually attained or attainable in a water body on or after November 28, 1975, whether or not they are included in these standards.

027 “Fecal Coliform” means the portion of the coliform bacteria group which is present in the gut or feces of warm-blooded animals and generally includes organisms which are capable of producing gas from lactose broth in a suitable culture medium within 24 hours at 44.5  0.5C.

028 “Four-Day Average” means an average of the daily mean values calculated over a period of four consecutive days.

029 “Hardness” means a characteristic of water which represents the total concentration of polyvalent cations (e.g., calcium, magnesium) expressed as calcium carbonate in mg/l. Hardness may be calculate for most waters by adding together the values obtained from multiplying the concentrations of calcium by 2.497 and magnesium by 4.116 to obtain the equivalent calcium carbonate concentration.

030 “High-Rate Diffusers” means devices attached to, or part of, a discharge outfall structure which provide discharge velocities that promote turbulent initial mixing of wastewaters with the receiving water.

031 “Hypolimnion” means the cold, relatively undisturbed lowermost layer of thermally stratified lakes.

032 “Key Species” means identified endangered, threatened, sensitive, or recreationally-important aquatic species associated with a particular water body and its aquatic life use class.

033 “Lake or Impounded Water” means any waterbody with all of the following characteristics:

(1) situated in a topographic depression or a dammed stream channel; (2) 30 percent or less areal coverage of trees, shrubs, persistent emergent aquatic plants, or emergent mosses; and (3) total area exceeds 20 acres. Similar waterbodies totaling less than 20 acres are also included if an active waveformed or bedrock shoreline feature makes up all or part of the boundary, or if the water depth in the deepest part of the basin exceeds 6.6 feet. Impounded waters in this definition may be manmade or naturally occurring collections or confinements of water. They do not include areas designated by the Department as wastewater treatment or wastewater retention facilities or irrigation reuse pits.

034 “LC50” means the statistical estimate of the concentration of a substance which kills 50 percent of the bioassay test organisms under test conditions specified or approved by the Department.

035 “Metalimnion” means the layer of a thermally stratified lake which exhibits a steep temperature gradient and separates the epilimnion above from the hypolimnion below.

036 “Milligrams per Liter (mg/L)” means the milligrams of substance per liter of solution, equivalent to parts per million assuming unit density of the solution.

037 “Mixing Zone” means the limited area or volume of a water body, as designated by the Department, which adjoins a point source discharge, and into which wastewaters which have received the applicable level of treatment or control are allowed to assimilate, disperse, dissipate, or undergo chemical transformation.

038 “Natural Background” means quantifiable measurements of water quality existing in the absence of water pollution.

039 “Noncontact Cooling Water” means water used to reduce temperature which does not come into direct contact with any raw material, intermediate product, waste product (other than heat), or finished product.

040 “Nonpoint Source” means any source of pollutants other than those defined as point sources.

041 “Nuisance Aquatic Life” means species of aquatic flora or fauna whose noxious characteristics or presence in sufficient numbers, biomass, or areal extent may reasonably be expected to prevent or interfere with a beneficial use.

042 “One-Day Minimum” means the lowest daily instantaneous value measured.

043 “One-Day Ten-Year (1Q10) Low Flow” means the discharge at the ten-year recurrence interval determined from a frequency distribution of annual values of the lowest discharge for one day.

044 “One-Hour Average” means an average of at least two appropriately spaced measurements, as determined by the Department, calculated over a period of one hour.

045 “Petroleum Oils” means all oils other than oils of vegetable and animal origin.

046 “pH” means the negative logarithm of the hydrogen ion concentration (pH = -log [H+]). pH expresses both the acidity and alkalinity of water on a scale from 0 to 14, with 7 representing neutrality (numbers less than 7 denote increasing acidity, and numbers greater than 7 denote increasing alkalinity).

047 “Pollutant” means any gas, liquid, or solid introduced into a body of water that causes water pollution. Pollutants under this definition include, but are not limited to, dredged spoil, solid waste, incinerator residue, sewage, garbage, sewage sludge, munitions, chemical wastes, biological materials, radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt, and industrial, municipal, and agricultural waste discharged into water.

048 “Recreationally-Important Species” means any game fish species identified by the Department, or any hybrid thereof, which is important to sport fishermen and readily affected by water quality degradation.

049 “Resident Species” means those species that typically occur in a water body including those that occur only seasonally or intermittently. Species that were once present but can no longer return due to physical habitat alterations are not included.

050 “Salmonid” means any fish belonging to the family Salmonidae. Trout are members of this family.

051 “Sensitive Species” means any aquatic species identified by the Department which has a limited distribution in the State and is indigenous to stable, high quality aquatic environments.

052 “Settleable Solids” means substances such as silt, organic detritus, plankton, or sand, which settle to the bottom of a water body or water column.

053 “Seven-Day Mean” means an average of the daily mean values calculated over a period of seven consecutive days.

054 “Seven-Day Mean Minimum” means an average of the one-day minimum values calculated over a period of seven consecutive days.

055 “Seven-Day Ten-Year (7Q10) High Flow” means the discharge at the ten-year recurrence interval determined from a frequency distribution of annual values of the highest average discharge for seven consecutive days.

056 “Seven-Day Ten-Year (7Q10) Low Flow” means the discharge at the ten-year recurrence interval determined from a frequency distribution of annual values of the lowest average discharge for seven consecutive days.

057 “Standards” means rules or regulations which are comprised of the water quality criteria that are necessary to protect the beneficial uses of surface waters.

058 “Substrate” means any naturally occurring or artificial solid surface which is emersed or submerged in water.

059 “Surface Waters” means all waters within the jurisdiction of this State, including all streams, lakes, ponds, impounding reservoirs, marshes, wetlands, watercourses, waterways, springs, canal systems, drainage systems, and all other bodies or accumulations of water, natural or artificial, public or private, situated wholly or partly within or bordering upon the State. Impounded waters in this definition do not include areas designated by the Department as wastewater treatment or wastewater retention facilities or irrigation reuse pits.

060 “Suspended Solids” means substances such as clay, silt, organic detritus, plankton, or sand, which are held in suspension by water currents or which exist in suspension as colloids.

061 “Synergistic Effects” means the cooperative action of discrete substances such that the cumulative effects are greater than the sum of the effects taken independently.

062 “Thermal Stratification” means a characteristic of certain lakes in which distinct layers of water that differ in density exist because of temperature differences. These layers are resistant to mixing with each other.

063 “Thirty-Day Five-Year (30Q5) High Flow” means the discharge at the five year recurrence interval determined from a frequency distribution of annual values of the highest average discharge for thirty consecutive days.

064 “Thirty-Day Five-Year (30Q5) Low Flow” means the discharge at the five-year recurrence interval determined from a frequency distribution of annual values of the lowest average discharge for thirty consecutive days.

065 “Thirty-Day Mean” or “Thirty-Day Average” means an average of the daily mean values calculated over a period of thirty consecutive days.

066 “Threatened Species” are identified by the Nebraska Game and Parks Commission in NAC Title 163, Chapter 4.

067 “Toxic Substances” means those pollutants or combination of pollutants, radioactive substances, or disease causing agents, which after discharge and upon exposure, ingestion, inhalation or assimilation into organisms, either directly from the environment or indirectly by ingestion through food chains, will on the basis of information available to the Department cause either death, disease, behavioral abnormalities, cancer, genetic mutations, physiological malfunctions (including malfunction in reproduction) or physical deformations, on such organisms or their offspring.

068 “Toxic Units (TU)” means the reciprocal of the effluent dilution that produces the bioassay endpoint.

069 “Twenty-four Hour Average” means an average of at least two appropriately spaced measurements, as determined by the Department, calculated over a period of 24 consecutive hours.

070 “Wastewater” means water containing sewage, and/or industrial wastes, including, but not limited to, discharges from sand and gravel operations, cooling water, storm water, street and road runoff, return flow from irrigation, feedlot runoff, or wastes resulting from land erosion and other discharges, treated or untreated, which enter directly or indirectly into the waters of the State or to any storm sewer, and including the runoff from land used for the disposition of wastes.

071 “Water Quality” means the biological, chemical, physical, and radiological integrity of a body of water.

071.01 “Biological Integrity” means the plant, animal, and bacteriological species composition of a body of water.

071.02 “Chemical Integrity” means the chemical properties of the water, sediments, or biological organisms (e.g., concentrations in fish tissue) of a body of water.

071.03 “Physical Integrity” means the physical properties (e.g., temperature, turbidity, sedimentation) of a body of water.

071.04 “Radiological Integrity” means the radioactive properties of the water, sediments, or biological organisms (e.g., concentrations in fish tissue) of a body of water.

072 “Water Quality Criteria” means the elements of standards which are expressed as concentrations, levels, or narrative statements and represent the quality of water that is necessary to protect a beneficial use.

073 “Wetland” means those areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas.

074 “Zone of Passage” means the area or volume of a water body outside of any mixing zone or zones which provides a continuous water route for the free passage of swimming and drifting aquatic organisms such that there are no adverse effects to their populations.

Enabling Legislation: Neb. Rev. Stat. §§ 81-1502 and 81-1505(1)(2)

Legal Citation: Title 117, Ch. 1, Nebraska Department of Environmental Quality

History

• Effective 2019-06-24

Chapter 2 Application of Standards

Neb. Admin. Code tit. 117, ch. 2 Application of Standards {#sec-117-nac-2 omnilex-key=us-ne-regs-official--title-117--117 NAC 2}

001 These standards apply at all times to all surface waters of the State except where noted below. Impounded waters designated by the Department as wastewater treatment facilities, wastewater retention facilities, or irrigation reuse pits are by definition (Chapter 1) not surface waters, thus standards do not apply to these waters.

002 The water quality criteria which may be necessary to protect downstream beneficial uses are applicable to all surface waters, whether or not those beneficial uses are assigned to a given water body in these Standards.

003 The application of standards for streams is be in accordance with Chapters 3, 4, and 5.

004 The application of standards for lakes and impounded waters is in accordance with Chapters 3, 4, and 6. Lakes and impounded waters not identified in Chapter 6 are protected for the assigned beneficial uses of the stream segments (Chapter 5) on which they are located. Water quality criteria associated with such beneficial uses are applicable to these lakes and impounded waters. Lakes not identified in Chapter 6 that are not located on stream segments are to be protected in accordance with 009 of this chapter.

004.01 In lakes and impoundments, or portions thereof, which exhibit natural thermal stratification, all applicable narrative and numerical criteria, with the exception of the numerical criteria for temperature, apply only to the epilimnion. Numerical temperature criteria apply at all depths (epilimnion, metalimnion, and hypolimnion) of lakes and impoundments exhibiting natural thermal stratification. In lakes and impoundments, or portions thereof, not exhibiting natural thermal stratification, the applicable narrative and numerical criteria apply at all depths.

005 The application of standards for wetlands is in accordance with Chapters 3 and 7.

006 These standards may be applied through Title 119 - Rules and Regulations Pertaining to the Issuance of Permits Under the National Pollutant Discharge Elimination System and Title 120 - Procedures Pursuant to Section 401 of the Federal Clean Water Act, 33 u.s.c. § 1251 et seq., for Certification by the Department of Activities Requiring a Federal License or Permit which May Result in a Discharge.

007 Narrative and numerical water quality criteria associated with aesthetics (Chapter 4, 005) and general criteria and acute toxicity criteria for protection of aquatic life (Chapter 4, 003) apply to all surface waters except as stated below in paragraphs 008, 010, 011, 012, and 013.

008 These standards, except water quality criteria associated with aesthetics (Chapter 4, 005), will not apply to effluents and non-contact cooling water discharges, although these standards are used in deriving effluent limitations pursuant to Title 119 - Rules and Regulations Pertaining to the Issuance of Permits Under the National Pollutant Discharge Elimination System.

009 These standards, except narrative and numerical water quality criteria associated with aesthetics (Chapter 4, 005) and general criteria and acute toxicity criteria for protection of aquatic life (Chapter 4, 003), will not apply to:

009.01 Streams assigned a Coldwater Class A, Coldwater Class B, or Warmwater Class A Aquatic Life use during periods when the flow is less than 0.1 cfs or the 7-day 10-year low flow, unless an assigned beneficial use still exists under these conditions. Thirty-day average ammonia criteria will not apply to these streams during periods when the flow is less than 0.1 cfs or the 30-day 5-year low flow unless an assigned beneficial use still exists under these conditions.

009.02 Streams assigned the Warmwater Class B Aquatic Life use during periods when the flow is less than 1.0 cfs, unless an assigned beneficial use still exists under this condition.

009.03 Undesignated surface waters except as necessary to protect assigned downstream beneficial uses. Acute criteria which are applicable to these surface waters include those applicable for the Warmwater Class B Aquatic Life use.

009.04 Streams during periods when the instantaneous flow is totally composed of effluent or non-contact cooling water discharges, excluding minor amounts of bank seepage, unless an assigned beneficial use still exists under these conditions.

010 These standards, except water quality criteria associated with aesthetics (Chapter 4, 005) and recreation (Chapter 4, 002) will not apply within mixing zones unless specified below. Mixing zones for the initial assimilation of effluents or wastewaters may be necessary where discharges that have received the applicable level of treatment or control still do not adequately protect the water quality of a receiving stream. Mixing zones are to be limited to as small an area and volume of a receiving stream as is practical to prevent interference with or impairment of any beneficial uses. The requirements of mixing zones for heat are to be defined on a site-specific basis, in a manner consistent with Section 316 of the Clean Water Act.

010.01 The Department determines the applicability of a mixing zone, and if applicable, the allowable size, location, water quality, and outfall design. The following requirements will be used in defining all mixing zones. These requirements are not intended to define each individual mixing zone, but represent maximum limits which will satisfy most biological, chemical, physical, and radiological considerations. A smaller mixing zone may be required or no zone at all allowed, as necessary, in order to meet these requirements.

010.02 The appropriateness, if any, of establishing a mixing zone for a pollutant which may be bioaccumulative, persistent, carcinogenic, mutagenic, or teratogenic will be carefully evaluated by the Department. In such cases, effects such as potential ground water contamination, known or predicted safe exposure levels for human health, bioaccumulation in aquatic life, fish attraction, sediment deposition, and protection of downstream beneficial uses will be considered.

010.03 Mixing zones established for dissolved oxygen are to take into account the delayed effects caused by oxidation of organic matter and ammonia inside and outside the mixing zone. One-day minimum dissolved oxygen criteria apply at the boundary of and beyond acute mixing zones, but not within acute mixing zones. All applicable dissolved oxygen criteria, including the one-day minimum criteria, are to be met at and beyond the mixing zone boundaries.

010.04 Mixing zones established for discharges impacting agricultural water supply criteria are to be based on the restrictions established for chronic mixing zones (010.06).

010.05 All mixing zone specifications are to be based on critical conditions of minimum dilution. Flow variable calculations that use real-time flows for a point source discharge and receiving stream may be allowed to determine critical conditions of minimum dilution. If flow variable critical conditions are not defined, critical conditions are to be determined as follows. The average dry weather or seasonal flow for a point source discharge will be used with the 7-day 10-year low flow of the receiving stream for application of all criteria with the exception of thirty-day average ammonia criteria and acute criteria for aquatic life. The 30-day 5-year low flow of the receiving stream will be used for application of thirty-day average ammonia criteria. The 1-day 10-year low flow of the receiving stream will be used for application of acute criteria.

010.06 Chronic Mixing Zones.

Chronic toxicity to aquatic life will not be allowed at any time outside of a chronic mixing zone.

010.06A The length of a chronic mixing zone is not to exceed the following distances based on designated aquatic life use classes.

010.06A1 Chronic mixing zones in Coldwater Class A, Coldwater Class B, and Warmwater Class B streams are to be designed to not exceed 2,500 feet in length.

010.06A2 Chronic mixing zones in Warmwater Class A streams are to be designed to not exceed 5,000 feet in length.

010.06B Chronic mixing zones are to be located in a receiving stream in such a manner that the maintenance of aquatic life and other beneficial uses will not be adversely affected.

010.06B1 A chronic mixing zone is not to overlap with any other mixing zone unless it is demonstrated to the satisfaction of the Department (e.g. aquatic field studies, bioassays in the site water using resident or acceptable nonresident aquatic species) that the overlapping of the mixing zones will not result in any adverse effects to aquatic life or other beneficial uses.

010.06B2 Chronic mixing zones are not to at any time:

010.06B2a Extend across public drinking water supply intakes.

010.06B2b Extend across heavily-used or state designated recreation bathing areas.

010.06B2c Extend into publicly owned lakes and reservoirs listed in Chapter 6.

010.06B2d Significantly impact federally and/or state designated threatened or endangered aquatic species.

010.06C Water quality of chronic mixing zones.

The Department may suspend the applicability of all or part of the water quality criteria within a chronic mixing zone, except those criteria relating to aesthetics (Chapter 4, 005) and acute toxicity to aquatic life (Chapter 4, 003.01C). In streams designated a recreational use, criteria relating to recreation (Chapter 4, 002) also apply within a chronic mixing zone. Waters at and beyond chronic mixing zone boundaries are to meet all chronic water quality criteria associated with the receiving stream any time the receiving streamflow is equal to or greater than 0.1 cfs for streams assigned a Coldwater Class A, Coldwater Class B, or Warmwater Class A Aquatic Life use; 1.0 cfs for streams assigned the Warmwater Class B Aquatic Life use; or its 7-day 10-year low flow (30-day 5 year low flow in the case of thirty-day average ammonia criteria), whichever is greater. To prevent chronic toxicity in a stream, the following conditions are to be met.

010.06C1 The pollutant levels or concentrations of wastewaters which contain unknown or complex mixtures of potentially additive or synergistic toxic pollutants are not to exceed 1.0 chronic toxic units (TUc) based on chronic bioassays representing the effluent dilution received at the chronic mixing zone boundary.

010.06C2 Where more than one wastewater discharge is located in a specific area and the potential exists for additive or synergistic effects, the pollutant levels or concentrations in water from a receiving stream outside any mixing zone are not to exceed 1.0 TUc based on chronic bioassays.

010.06C3 Where a mixing zone is not allowed by the Department, the pollutant levels or concentrations of the wastewater in the outfall structure itself are not to exceed the No Observed Effect Level (NOEL) based on chronic bioassays of the undiluted effluent. NOEL is the threshold concentration of a substance which causes no observed adverse effects to bioassay test organisms under test conditions specified or approved by the Department.

010.07 Acute Mixing Zones.

Acute toxicity to aquatic life will not be allowed at any time outside of an acute mixing zone.

010.07A Acute mixing zones are to allow at all times for a continuous zone of passage in the receiving stream for the movement or drift of aquatic biota. To provide for a zone of passage, the width of an acute mixing zone at any transect of the receiving stream is not to exceed more than 1/2 of the stream width. Where more than one wastewater discharge is located in a specific area, acute mixing zones are to be located in such a manner as to provide for a continuous zone of passage of at least 1/2 the stream width.

010.07B The length of an acute mixing zone is not to exceed the following distances based on designated aquatic life use classes.

010.07B1 Acute mixing zones in Coldwater Class A, Coldwater Class B, and Warmwater Class B streams are to be designed to not exceed 125 feet in length or 5 percent of the length of the chronic mixing zone whichever is more restrictive.

010.07B2 Acute mixing zones in Warmwater Class A streams are to be designed to not exceed 250 feet in length or 5 percent of the length of the chronic mixing zone whichever is more restrictive.

010.07C Acute mixing zones are to be located in a receiving stream in such a manner that the maintenance of aquatic life and other beneficial uses will not be adversely affected. Acute mixing zones are not to at any time:

010.07C1 Extend across public drinking water supply intakes.

010.07C2 Extend across heavily-used or state designated recreation bathing areas.

010.07C3 Extend into publicly owned lakes and reservoirs listed in Chapter 6.

010.07C4 Significantly impact federally and/or state designated threatened or endangered aquatic species.

010.07C5 Extend across the mouth of a classified tributary stream segment.

010.07D Water quality of acute mixing zones.

The Department may suspend the applicability of all or part of the water quality criteria within an acute mixing zone, except those criteria relating to aesthetics (Chapter 4, 005). In streams designated a recreational use, criteria relating to recreation (Chapter 4, 002) also apply within the acute mixing zone. Waters at and beyond acute mixing zone boundaries are to meet all acute water quality criteria associated with the receiving stream any time the receiving streamflow is equal to or greater than 0.1 cfs or its 1-day 10-year low flow.

010.07D1 The pollutant levels or concentrations of wastewaters which contain unknown or complex mixtures of potentially additive or synergistic toxic pollutants are not to exceed 0.3 acute toxic units (TUa) based on acute bioassays representing the effluent dilution received at the acute mixing zone boundary.

010.07D2 Where more than one wastewater discharge is located in a specific area and the potential exists for additive or synergistic effects, the pollutant levels or concentrations in water from a receiving stream outside any acute mixing zone are not to exceed 0.3 TUa based on acute bioassays.

010.07D3 Where a mixing zone is not allowed by the Department, the pollutant levels or concentration of the wastewater in the outfall structure itself are not to exceed 0.3 TUa based on acute bioassays of the undiluted effluent.

010.08 Mixing Zones for Public Drinking Water Supply Criteria.

In waters designated as Water Supplies for Public Drinking Water, the criteria for protection of public drinking water supplies are not to be exceeded at any time outside of a mixing zone for public drinking water supply criteria.

010.08A Mixing zones for public drinking water supply criteria are to be designed to not extend to within a 2 mile zone of influence from any public drinking water supply intake.

010.08B Mixing zones for public drinking water supply criteria are to be located in a receiving stream in such a manner that other beneficial uses will not be adversely affected.

010.08C Water quality of mixing zones for public drinking water supply criteria. The Department may suspend the applicability of all or part of the water quality criteria for the protection of public drinking water supplies within a mixing zone for public drinking water supply criteria. Waters at and beyond boundaries of mixing zones for public drinking water supply criteria are to meet all public drinking water supply criteria any time the receiving stream is flowing equal to or greater than its 7-day 10-year low flow.

010.09 Outfall Design.

Prior to designating a mixing zone, the Department will first approve pursuant to Title 123 - Rules and Regulations for Design, Operation, and Maintenance of Wastewater Treatment Works that the best practical engineering design for the outfall structure and its location and placement in the receiving stream have been applied, as necessary, to meet all mixing zone requirements for size, location, and water quality.

010.09A The following are acceptable circumstances for modifying the existing design, location, or placement of an outfall structure in a stream:

010.09A1 Where high-rate diffusers or similar devices are required to:

(1) minimize or prevent exposure of aquatic biota to acutely toxic conditions within an acute mixing zone, (2) minimize or prevent exposure of aquatic biota to possible irreversible chronic effects within a mixing zone where wastewaters tend to attract aquatic organisms, or (3) otherwise expedite mixing and dispersion of wastewaters in order to meet mixing zone requirements for size, location, and water quality.

010.09A2 Where changes are required in the location of an outfall structure (e.g., upstream, downstream, or to the opposite stream bank) or its placement (e.g., water depth, direction in relation to the stream current) in order to meet mixing zone requirements for size, location, and water quality.

010.09B Water turbulence created by high-rate diffusers or similar devices is not to be of such a magnitude that the movement or drift of aquatic biota within a zone of passage is interfered with or prevented.

011 Water quality criteria in Chapters 4 and 7 related to aquatic herbicides or algicides and their effects will not apply to waters within canals, except those canals designated as segments in Chapter 5, during periods when these chemicals are applied by an irrigation district for the control of aquatic plants.

011.01 All standards apply at all times to waters within canals designated as segments in Chapter 5.

011.02 Discharges from canal to other surface waters of the State are not to, at any time, contain herbicides or algicides in amounts which are toxic to aquatic life.

012 Water quality criteria in Chapters 4 and 7 related to aquatic biocides (e.g., ichthyocides, algicides, herbicides) and their effects will not apply to surface waters during periods when aquatic biocides are applied by an entity responsible for the management of a surface water body under the following conditions:

012.01 Aquatic biocides are to be applied only for the purposes of attaining, maintaining, or enhancing beneficial uses identified in Chapters 4, 5, 6 and 7.

012.02 Application of aquatic biocides are not to cause adverse impacts to any assigned beneficial uses of surface waters beyond the targeted surface water body.

012.03 Application of aquatic biocides are to be in accordance with the label restrictions and all applicable federal, state, and local laws or regulations.

012.04 Entities responsible for the management of surface water bodies may include the Nebraska Game and Parks Commission, Natural Resources Districts, U.S. Fish and Wildlife Service, U.S. Forest Service, National Parks Service, U.S. Army Corps of Engineers, city governments, or any other entity responsible for managing the surface water body’s assigned beneficial uses.

013 These standards will not apply to :

013.01 Waters below existing hydroelectric plants during periods of approved sluicing activities, provided the hydroelectric plant was operational prior to May 10, 1982. The Department will determine when sluicing activities will be allowed.

013.01A Sluicing activities will be conducted in such a manner as to minimize any harmful effects on assigned beneficial uses.

013.01B Sluicing is not to occur immediately before or during critical reproductive periods of identified key species.

013.01C In the event that the sluicing activity has been determined to have a deleterious impact on the aquatic biota of the State waters, the operator is to pay to the Game and Parks Commission annually the lesser of A., $5000.00, or B., 20% of the annual damages, which is the fair market mitigation to the fisheries resulting from the sluicing activity.

013.02 Waters within canals designated as segments in Chapter 5 during periods of dewatering which are required for or may result from repair, maintenance, inspection, non-diversion periods, force majeure or public safety.

014 Because the frequency and extent of monitoring programs can only approximate whether surface waters meet or exceed water quality criteria that are based on averages over a specified time period in Chapters 4 and 7, assessment of compliance with these criteria may utilize scientifically accepted statistical procedures.

015 Variances .

015.01 Upon written application by any person and meeting the requirements of this section, the director may grant a variance for an interim beneficial use and interim criterion when it is determined that the attainment of a current beneficial use and criterion is not feasible because one of the following conditions is met:

015.01A One of the factors listed in 40 C.F.R 131.10(g) dated July 1, 2018, which is adopted and incorporated by reference, exists.

015.01B Actions necessary to facilitate lake, wetland, or stream restorations through dam removal or other significant reconfiguration activities preclude attainment of the designated use and criterion while the actions are being implemented.

015.02 Prior to the granting of any variance as allowed by 015.01, persons or categories of facilities eligible for an interim beneficial use and interim criterion will be proposed for adoption by the Nebraska Environmental Quality Council, after a public hearing consistent with 40 C.F.R. 131.20(b) dated July 1, 2018, which is adopted and incorporated by reference. Categories of eligible facilities will be identified and proposed in conjunction with the next systematic review or subsequent triennial review.

015.03 Adoption and implementation of each variance will be in accordance with 40 C.F.R 131.14 dated July 1, 2018, which is adopted and incorporated by reference, except that 131.14(a)(2), 131.14(b)(1)(ii), and 131.14(b)(2)(i)(A) are to be replaced by paragraphs 015.04 through 015.06 of this regulation, respectively.

015.04 Each variance will have a designated term limit and reflect the highest attainable condition during the specified term. A variance may be applied to individual or multiple dischargers or surface water bodies.

015.05 Each variance will have requirements and a time limitation demonstrating the intent that progress be made toward the attainment of the underlying designated use and criterion.

015.05A Each Nebraska surface water quality standard not specifically addressed in a variance will remain applicable.

015.05B Each person requesting a variance is to provide evidence that a designated use and criterion, or a designated use or criterion addressed by the variance cannot be achieved solely by the implementation of technology-based effluent limits.

015.05C Each requirement of the variance is to represent the highest attainable condition of the surface water segment applicable throughout the term of the variance. A specified requirement will not result in lowering the currently attained ambient water quality, unless a variance is necessary for physical reconfiguration activities intended for surface water segment restoration. The highest attainable condition of each affected surface water segment as a quantifiable expression is to be specified as one of the following:

015.05C1 The highest attainable interim criterion;

015.05C2 The interim effluent condition that reflects the greatest pollutant reduction achievable; or

015.05C3 The interim criterion or effluent condition that reflects the greatest pollutant reduction achievable with the pollutant control technologies installed at the time the variance is adopted.

015.05D If the quantifiable expression identified in paragraph 015.05C3 is selected, a pollutant minimization plan consistent with 40 C.F.R 131.3(p) dated July 1, 2018, which is adopted and incorporated by reference, is to be adopted and implemented if no additional feasible pollutant control technology is identified.

015.06 Each variance request will include supporting documentation that demonstrates all of the following:

015.06A Attaining the designated use and criterion is not feasible throughout the term of the variance because of one of the factors cited in paragraphs 015.01A and 015.01B;

015.06B The term of the variance is only as long as necessary to achieve the highest attainable condition; and

015.06C The highest attainable condition of the affected surface water segment is as defined in paragraph 015.05C.

015.07 A discharger that adversely impacts water quality will not be granted a variance from requirements of Title 117, Chapter 3.

015.08 Specific eligibility requirements may be included in a multiple-discharger variance as an alternative to identifying the specific dischargers at the time of adoption of the variance. Each discharger is to meet the eligibility requirements in the applicable section of the “Nebraska Surface Water Quality Standards Variance Register”, which will be made available to the public by the Department on its web site.

Enabling Legislation: Neb. Rev. Stat. §81-1505(1)(2)

Legal Citation: Title 117, Ch. 2, Nebraska Department of Environmental Quality

History

• Effective 2019-06-24

Chapter 3 Antidegradation Clause

Neb. Admin. Code tit. 117, ch. 3 Antidegradation Clause {#sec-117-nac-3 omnilex-key=us-ne-regs-official--title-117--117 NAC 3}

001 The water quality of surface waters, consistent with uses applied in these Standards, shall be maintained and protected. Water quality degradation which would adversely affect existing uses will not be allowed.

002 State Resource Waters - Class A - These are surface waters, whether or not they are designated in these Standards, which constitute an outstanding State or National resource, such as waters within national or state parks, national forests or wildlife refuges, and waters of exceptional recreational or ecological significance. Waters which provide a unique habitat for federally designated endangered or threatened species and rivers designated under the Wild and Scenic Rivers Act are also included. The existing quality of these surface waters shall be maintained and protected.

003 State Resource Waters - Class B - These are surface waters, whether or not they are designated in these Standards, which possess an existing quality which exceeds levels necessary to maintain recreational and/or aquatic life uses. The existing water quality of these surface waters shall be maintained and protected. However, the State may choose, in accordance with Neb. Rev. Stat. § 81-1513, to allow lower water quality as a result of important and necessary economic or social development in the area. There shall be achieved the highest statutory and regulatory requirements for all new and existing point sources and all cost-effective and reasonable best management practices for nonpoint source control. In cases where potential water quality impairment associated with a thermal discharge is involved, the method of implementation of this antidegradation policy shall be consistent with Section 316 of the Clean Water Act.

004 In implementing this policy, the Department will follow the procedures outlined in the State’s Continuing Planning Process.

Enabling Legislation: Neb. Rev. Stat. §§ 81-1501(1) and 81-1505(1)(2)

Legal Citation: Title 117, Ch. 3, Nebraska Department of Environmental Quality

History

• Effective 1996-03-06

Chapter 4 Standards for Water Quality

Neb. Admin. Code tit. 117, ch. 4 Standards for Water Quality {#sec-117-nac-4 omnilex-key=us-ne-regs-official--title-117--117 NAC 4}

001 It is the public policy of the State of Nebraska to protect and improve the quality of surface water for human consumption, wildlife, fish and other aquatic life, industry, recreation, and other productive, beneficial uses.

Beneficial uses are assigned to surface waters within or bordering upon the State of Nebraska (Chapters 5 and 6). Assigned and existing beneficial uses are protected by the Antidegradation Clause (Chapter 3) and the narrative and numerical water quality criteria in this chapter. Beneficial uses are also protected by permits issued in accordance with the requirements of these standards, and through Department requirements for the applicable level of treatment or control for point and nonpoint sources of pollution. Some uses require higher quality water than others. When multiple uses are assigned to the same waters, all assigned uses will be protected.

The beneficial uses defined by these standards are:

Primary Contact Recreation

Aquatic Life

Coldwater (Class A and B) Warmwater (Class A and B)

Water Supply

Public Drinking Water Agricultural Industrial

Aesthetics

These uses are not intended in any way to conflict with the quantitative beneficial uses provided for in Neb. Rev. Stat., Ch. 46, regulating irrigation or the authority of the Nebraska Department of Natural Resources.

002 Primary Contact Recreation .

This use applies to surface waters which are used, or have a high potential to be used, for primary contact recreational activities. Primary contact recreation includes activities where the body may come into prolonged or intimate contact with the water, such that water may be accidentally ingested and sensitive body organs (e.g., eyes, ears, nose, etc.) may be exposed. Although the water may be accidentally ingested, it is not intended to be used as a potable water supply unless acceptable treatment is applied. These waters may be used for swimming, water skiing, canoeing, and similar activities. These criteria apply during the recreational period of May 1 through September 30.

002.01 E. coli .

E. coli bacteria are not to exceed a geometric mean of 126/100 ml. For increased confidence of the criteria, the geometric mean should be based on a minimum of five samples taken within a 30-day period. This does not preclude fecal coliform limitations based on effluent guidelines. The following single sample maxima will be used solely for issuing periodic public advisories regarding use of waterbodies for Primary Contact Recreation.

002.01A 235/100 ml at designated bathing beaches.

002.01B 298/100 ml at moderately used recreational waters.

002.01C 406/100 ml at lightly used recreational waters.

002.01D 576/100 ml at infrequently used recreational waters.

002.02 Toxic Substances.

These waters are to be free from toxic substances, alone or in combination with other substances, in concentrations that result in adverse health impacts to humans participating in primary contact recreation.

003 Aquatic Life .

003.01 General Criteria for Aquatic Life

The following criteria apply to all aquatic life use classes.

003.01A pH (Hydrogen Ion Concentration).

Hydrogen Ion concentrations, expressed as pH, are to be maintained between 6.5 and 9.0; unless pH values outside this range are due to natural conditions.

003.01B Temperature.

The temperature of a receiving water is not to be increased by a total of more than 5^oF (3^oC) from natural background outside the mixing zone.

For the Missouri River, from the South Dakota-Nebraska state line near Ft. Randall Dam to Sioux City, Iowa, the maximum temperature limit is 85^oF (29^oC) with an allowable change of 4^oF (2^oC) from natural background. For cold waters, the maximum limit is 72^oF (22^oC) with an allowable change of 5^oF (3^oC) from natural background. For warm waters, the maximum limit is 90^oF (32^oC).

For impoundments, the temperature of the epilimnion of surface waters is not to be raised more than 3^oF (2^oC) above that which existed before the addition of heat of artificial origin. Unless a special study shows that the discharge of heated effluent into the hypolimnion will be desirable, such practice is not recommended and water for cooling should not be pumped from the hypolimnion to be discharged to the same body of water.

003.01C Toxic Substances.

Surface waters are to be free from toxic substances, alone or in combination with other substances, in concentrations that result in acute or chronic toxicity to aquatic life, except as specified in Chapter 2. Toxic substances are not to be present in concentrations that result in objectionable tastes or significant bioaccumulation or biomagnification in aquatic organisms which renders them unsuitable or unsafe for consumption. (In implementing these criteria, the Department will follow procedures outlined in the State’s Continuing Planning Process which comply with the federal water quality standards, 40 C.F.R. § 131.11 (1987)).

003.01C1 The following numerical criteria for the protection of aquatic life and their uses (e.g., fish consumption) are not to be exceeded. Unless otherwise noted, criteria are based on total concentrations.

• Chemical Abstract Services Registry Number

^a Concentration not to be exceeded at any time ^b Twenty-four hour average concentration ^c One-hour average concentration ^d Four-day average concentration ^e Human health criteria at the 10-5 risk level for carcinogens based on the consumption of fish and other aquatic organisms ^f Human health criteria based on the consumption of fish and other aquatic organisms

¹ Dimethyl tetrachloroterephthalate ² 2,3,7,8-tetrachloro-dibenzo-p-dioxin or 2,3,7,8-TCDD ³ Criteria for metals and inorganics apply to dissolved concentrations ⁴ The conversion factor for lead (acute and chronic) is hardness dependent and defined by:

CF = 1.46203- [(ln hardness)(0.145712)]

⁵ Chronic criterion for mercury applies to total recoverable concentrations

003.01C2 The following criteria for the protection of human health based on consumption of fish and other aquatic organisms are not to be exceeded. These criteria are expressed as fish tissue concentrations (mg/kg fish).

*Chemical Abstract Services Registry Number

003.01C3 The following Selenium criteria are for the protection of aquatic life. These criteria are expressed preferentially as fish tissue concentrations (mg/kg fish), followed by water column concentrations (mg/L) in the absence of fish tissue information.

^1.Fish tissue elements are expressed as steady-state. ^2.Egg/Ovary supersedes any whole-body, muscle, or water column element when fish egg/ovary concentrations are measured. ^3.Fish whole-body or muscle tissue supersedes water column element when both fish tissue and water column concentrations are measured. ^4. Water column values are based on dissolved total selenium in water and are derived from fish tissue values via bioaccumulation modeling. Water column values are the applicable criterion element in the absence of steady-state condition fish tissue data. ^5.Where WQC30-day is the water column monthly element, for either a lake or stream; Cbkgrnd is the average background selenium concentration, and ƒint is the fraction of any 30-day period during which elevated selenium concentrations occur, with ƒint assigned a value ≥0.033 (corresponding to 1 day). ^6.Fish tissue data provide instantaneous point measurements that reflect integrative accumulation of selenium over time and space in fish populations at a given site.

• Chemical Abstract Services Registry Number

003.01D Petroleum Oil.

Not to exceed 10 mg/L.

003.01E Total Dissolved Gases.

Not to exceed 110 percent of the saturation value for gases at the existing atmospheric and hydrostatic pressures.

003.01F Hydrogen Sulfide.

Not to exceed 0.002 mg/L as undissociated hydrogen sulfide.

003.01G Chloride.

Not to exceed 860 mg/L at any time or a four-day average concentration of 230 mg/L except as specified in 003.02B2 (Site-specific criteria).

003.01H Alkalinity

No less than 20 mg/L as CaCO3 except where natural background is less.

003.01I Residual Chlorine.

003.01I1 One-hour average concentration not to exceed 19μg/L.

003.01I2 Four-day average concentration not to exceed 11 μg/L.

003.01J Biological Criteria.

Any human activity causing water pollution which would significantly degrade the biological integrity of a body of water or significantly impact or displace an identified “key species” will not be allowed except as specified in Chapter 2.

003.01J1 Key Species.

Key species are identified endangered, threatened, sensitive, or recreationally-important aquatic species. Key species are designated by stream segment (Chapter 5).

003.02 Site-Specific Criteria for Aquatic Life.

003.02A Procedures for Developing Site-specific Water Quality Criteria.

The water quality criteria in Chapter 4 may not always reflect the toxicity of a chemical in a specific water body. These criteria also represent only a limited number of the natural and manmade chemicals that exist in the environment which may pose a threat to aquatic life. Thus, it may be necessary in some water bodies to develop new water quality criteria or modify existing criteria through site-specific analyses in order to more accurately protect the resident species.

003.02A1 The following are acceptable conditions for developing site-specific criteria.

003.02A1a Resident species of a water body are more or less sensitive than those species used to develop a water quality criterion.

003.02A1a(1) Natural adaptive processes have enabled a viable, balanced aquatic community to exist in waters where natural background levels of a chemical exceed the criterion (e.g., resident species have evolved a genetically- based greater resistance to high concentrations of a chemical).

003.02A1a(2) The composition of aquatic species in a water body is different from those used in deriving a criterion (e.g., most of the species considered among the most sensitive, such as salmonids or the cladoceran, Daphnia magna, which were used in developing a criterion, are absent from a water body).

003.02A1b Biological availability and/or toxicity of a chemical may be altered due to differences between the physical and/or chemical characteristics of the water in a water body and the laboratory water used in developing a criterion (e.g., alkalinity, hardness, pH, salinity, suspended solids, turbidity, water temperature).

003.02A1b(1) The effect of seasonality on the physical and/or chemical characteristics of a water body and subsequent effects on biological availability and/or toxicity of a chemical may justify seasonally dependent site-specific criteria.

003.02A2 To insure that the approach to be used in developing site-specific criteria is acceptable, the Department should be involved early in the planning of any site-specific analyses so that an agreement can be reached concerning the availability of existing data, additional data needs, methods to be used in generating new data, testing procedures to be used, schedules to be followed, and quality control and assurance provisions to be used. It is particularly important to involve the Department in the planning of site-specific analyses if a party other than the Department will be conducting the data generation and testing.

003.02A3 Site-specific criteria are to protect all life stages of resident species year-round (or seasonally for seasonally dependent criteria) and prevent acute and chronic toxicity in all parts of a water body. If site-specific criteria are seasonally dependent, the period when the criteria apply is to be clearly identified.

003.02A4 Site-specific criteria are to include both chronic and acute concentrations to better reflect the different tolerances of resident species to the inherent variability between concentrations and toxicological characteristics of a chemical.

003.02A5 Site-specific criteria are to be clearly identified as maximum “not to be exceeded” or average values, and if an average, the averaging period. The conditions, if any, when the criteria apply are to be clearly stated (e.g., specific levels of hardness, pH, or water temperature). Specific sampling requirements (e.g., location, frequency), if any, are to also be identified.

003.02A6 The following are acceptable procedures for developing site-specific criteria.

003.02A6a Site-specific analyses for the development of new water quality criteria are to be conducted in a manner which is scientifically justifiable and consistent with the assumptions and rationale in Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and their Uses, EPA, 1985.

003.02A6b Site-specific analyses for the modification of existing water quality criteria are to be conducted in accordance with one of the following procedures. These procedures are described in Water Quality Standards Handbook, EPA, December 1983.

003.02A6b(1) Recalculation procedure. This procedure is used to account for differences in sensitivity to a chemical between resident species and those species used in deriving the criterion. Bioassays in laboratory water may be required for untested resident species. Adaptation of numerical toxics criteria to site-specific conditions is explained in Recalculation of State Toxic Criteria, EPA, November 1983.

003.02A6b(2) Indicator species procedure. This procedure is used to account for differences in biological availability and/or toxicity of a chemical between the physical and/or chemical characteristics of the water in a water body and the laboratory water used in developing the criterion. Bioassays in site water using resident species or acceptable nonresident species are required. Reconditioned laboratory water simulating site-specific water quality conditions is an acceptable substitute for site water.

003.02A6b(3) Resident species procedure. This procedure is used to account for differences in both resident species sensitivity and biological availability and/or toxicity of a chemical. Bioassays in site water using resident species are required. Reconditioned laboratory water simulating site-specific water quality conditions is an acceptable substitute for site water.

003.02A6b(4) Other scientifically defensible procedures such as relevant aquatic field studies, laboratory tests, or available scientific literature.

003.02A6b(4)(a) Deviations from EPA procedures are to have justifications which are adequately documented and based on sound scientific rationale.

003.02A6b(4)(b) The data, testing procedures, and application (safety) factors used to develop site-specific criteria are to reflect the nature of the chemical (e.g., persistency, bioaccumulation potential, and avoidance or attraction responses in fish) and the most sensitive resident species of a water body.

003.02A7 A site may be limited to the specific area affected by a point or nonpoint source of pollution; or, if water quality effects on toxicity are not a consideration, the site may be as large as a general biogeographical area permits (e.g., ecoregion, river basin, subbasin). For a number of different water bodies to be designated as one site, their respective aquatic communities cannot vary substantially in sensitivity to a chemical.

003.02B Site-Specific Water Quality Criteria.

003.02B1 Lake Ogallala (Keith County).

003.02B1a Dissolved Oxygen.

The following criteria apply from July 1 through October 15 as specified below. When the Kingsley Hydropower Plant is in operation (generating electricity), these criteria are based on water temperature measurements taken continuously and averaged every hour in the power house of the Kingsley Hydropower Plant and on dissolved oxygen measurements taken continuously and averaged every 10 minutes from Lake Ogallala at the midpoint of the buoy line (1987 location at the outer edge of the stilling basin) at a one meter depth. For purposes of calculating seven-day mean, seven- day mean minimum, and thirty-day mean values at the buoy line, seven-day and thirty-day calculation periods are to be based on a sequence of days not to include any day in which the Kingsley Hydropower Plant is not in operation. The following criteria may also be based on temperature and dissolved oxygen measurements taken from Lake Ogallala at any location except the metalimnion and hypolimnion when the lake exhibits thermal stratification.

003.02B1a(1) When daily mean water temperatures are 18°C or less the following criteria apply:

003.02B1a(1)(a) One-day minimum of not less than 3.0 mg/L.

003.02B1a(1)(b) Daily mean of not less than 4.0 mg/L and no more than 20 percent of the one-day mean values less than 4.2 mg/L.

003.02B1a(1)(c) Seven-day mean of not less than 4.3 mg/L.

003.02B1a(2) When daily mean water temperatures exceed 18°C for four consecutive days of operation, the following criteria apply for as long as daily mean water temperatures continue to exceed 18°C. These criteria take effect on the fifth day of daily mean water temperatures exceeding 18°C.

003.02B1a(2)(a) One-day minimum of not less than 4.0 mg/L.

003.02B1a(2)(b) Daily mean of not less than 5.0 mg/L.

003.02B1a(3) When daily mean water temperatures exceed 18°C for fifteen consecutive days of operation, or when daily mean water temperatures exceed 20C the dissolved oxygen criteria for Class B - Coldwater Aquatic Life (Chapter 4, 003.03B1) apply as long as daily mean water temperatures continue to exceed 18°C. These criteria take effect on the sixteenth day of daily mean water temperatures exceeding 18°C or on the first day after daily mean water temperatures exceed 20°C.

003.02B1a(4) In implementing paragraphs 003.02B1a(2) and 003.02B1a(3), if an interruption in the operation of Kingsley Hydropower Plant exceeding 24 hours occurs during the count of days leading to a change in criteria, the count of days will be suspended until the plant is back in operation. The first new day of operation is to be counted as the next consecutive day in the original count of days.

003.02B1b Dissolved oxygen criteria for Class B - Coldwater Aquatic Life (Chapter 4, 003.03B1) apply during the period of October 16 through June 30.

003.02B2 Salt Creek – Beal Slough to Platte River (segments LP2-10000 and LP2-20000), Rock Creek (segments LP2-11000, LP2-11100, and LP2-11200, North Fork Rock Creek (segment LP2-11010), Ash Hollow Creek (segment LP2-11110), Little Rock Creek (segment LP2-11120), Jordan Creek (segment LP2-20100), Little Salt Creek (segment LP2-20300), Oak Creek - Elk Creek to Salt Creek (segment LP2-20500), Antelope Creek (segment LP2-20900), Middle Creek - South Branch Middle Creek to Salt Creek (segment LP2-21000), Haines Branch - Holmes Creek to Salt Creek (segment LP2-21200), Holmes Creek (segment LP2-21210), and Oak Lake (lake LP2-L0060). All waterbodies are within the Lower Platte River Basin.

003.02B2a Chloride.

Because these segments have high natural background concentrations of chloride and aquatic life has adapted to these conditions, criteria will be based on natural background values.

003.03 Coldwater Aquatic Life Use Class Specific Criteria.

These are waters which provide, or could provide, a habitat consisting of sufficient water volume or flow, water quality, and other characteristics such as substrate composition which are capable of maintaining year-round populations of coldwater biota. Coldwater biota are considered to be life forms in waters where temperatures seldom exceed 25°C (77°F).

003.03A Total Ammonia (as nitrogen).

003.03A1 One-hour average concentration in mg/L not to exceed the numerical value given by

where Temp is °C

ONE-HOUR AVERAGE CRITERIA FOR TOTAL AMMONIA (mg/L)

Coldwater Aquatic Life Use Classes

003.03A2 Thirty-day average concentration in mg/L not to exceed the numerical value given by

where Temp is °C

003.03A2a The highest four-day average concentration within a thirty-day period is not to exceed 2.5 times the thirty-day criterion.

003.03A2b The following table shows thirty-day average criteria for total ammonia at various temperatures and pHs.

THIRTY-DAY AVERAGE CRITERIA FOR TOTAL AMMONIA (mg/L)

Coldwater Aquatic Life Use Class

003.03B Toxic Substances.

003.03B1 The following numerical criteria are not to be exceeded.

^a One-hour average concentration ^b Four-day average concentration ¹ Criteria for metals and inorganics apply to dissolved concentrations ² The conversion factors for cadmium are hardness dependent and defined by:

ACF = 1.136672-[1n hardness (0.041838)] CCF = 1.101672-[1n hardness (0.041838)]

003.03C Class A - Coldwater.

These waters provide a habitat which supports natural reproduction of a salmonid (trout) population. These waters also are capable of maintaining year-round populations of a variety of other coldwater fish and associated vertebrate and invertebrate organisms and plants.

003.03C1 Dissolved Oxygen.

003.03C1a One-day minimum of not less than 8.0 mg/L for salmonid early-life stages. This criterion applies from October 1 through May 31.

003.03C1b One-day minimum of not less than 4.0 mg/L for all life stages other than salmonid early-life stages. This criterion applies from June 1 through September 30.

003.03C1c Seven-day mean minimum of not less than 5.0 mg/L. This criterion applies from June 1 through September 30.

003.03C1d Seven-day mean of not less than 9.5 mg/L for salmonid early-life stages. This criterion applies from October 1 through May 31.

003.03C1e Thirty-day mean of not less than 6.5 mg/L. This criterion applies from June 1 through September 30.

003.03D Class B - Coldwater.

These are waters which provide, or could provide, a habitat capable of maintaining year-round populations of a variety of coldwater fish and associated vertebrate and invertebrate organisms and plants or which support the seasonal migration of salmonids. These waters do not support natural reproduction of salmonid populations due to limitations of flow, substrate composition, or other habitat conditions, but salmonid populations may be maintained year-round if periodically stocked.

003.03D1 Dissolved Oxygen.

003.03D1a One-day minimum of not less than 5.0 mg/L for coldwater fish early-life stages. This criterion applies from April 1 through June 30.

003.03D1b One-day minimum of not less than 4.0 mg/L for all life stages other than coldwater fish early-life stages. This criterion applies from July 1 through March 31.

003.03D1c Seven-day mean minimum of not less than 5.0 mg/L. This criterion applies from July 1 through March 31.

003.03D1d Seven-day mean of not less than 6.5 mg/L for coldwater fish early-life stages. This criterion applies from April 1 through June 30.

003.03D1e Thirty-day mean of not less than 6.5 mg/L. This criterion applies from July 1 through March 31.

003.04 Warmwater Aquatic Life Use Class Specific Criteria.

These are waters which provide, or could provide, a habitat consisting of sufficient water volume or flow, water quality, and other characteristics such as substrate composition which are capable of maintaining year-round populations of warmwater biota. Warmwater biota are considered to be life forms in waters where temperatures frequently exceed 25°C (77°F).

003.04A Total Ammonia (as nitrogen).

003.04A1 One-hour average concentration in mg/L not to exceed the numerical value given by

where Temp is °C

003.04A1a The following table shows one-hour average criteria for total ammonia at various temperatures and pHs.

ONE-HOUR AVERAGE CRITERIA FOR TOTAL AMMONIA (mg/L)

Warmwater Aquatic Life Use Classes

003.04A2 Thirty-day average concentration in mg/L not to exceed the numerical value given by

where Temp is °C

003.04A2a The highest four-day average concentration within a thirty-day period is not to exceed 2.5 times the thirty-day criterion.

003.04A2b The following table shows thirty-day average criteria for total ammonia at various temperatures and pHs.

THIRTY-DAY AVERAGE CRITERIA FOR TOTAL AMMONIA (mg/L)

Warmwater Aquatic Life Use Classes

003.04B Toxic Substances.

003.04B1 The following numerical criteria are not to be exceeded.

^a One-hour average concentration ^b Four-day average concentration ¹ Criteria for metals and inorganics apply to dissolved concentrations ² The conversion factors for cadmium are hardness dependent and defined by:

ACF = 1.136672-[1n hardness (0.041838)] CCF = 1.101672-[1n hardness (0.041838)]

003.04C Class A - Warmwater.

These waters provide, or could provide, a habitat suitable for maintaining one or more identified key species on a year-round basis. These waters also are capable of maintaining year-round populations of a variety of other warmwater fish and associated vertebrate and invertebrate organisms and plants.

003.04C1 Dissolved Oxygen.

003.04C1a One-day minimum of not less than 5.0 mg/L for early-life stages. This criterion applies from April 1 through September 30.

003.04C1b One-day minimum of not less than 3.0 mg/L for all life stages other than early-life stages. This criterion applies from October 1 through March 31.

003.04C1c Seven-day mean minimum of not less than 4.0 mg/L. This criterion applies from October 1 through March 31.

003.04C1d Seven-day mean of not less than 6.0 mg/L for early-life stages. This criterion applies from April 1 through September 30.

003.04C1e Thirty-day mean of not less than 5.5 mg/L. This criterion applies from October 1 through March 31.

003.04D Class B - Warmwater.

These are waters where the variety of warmwater biota is presently limited by water volume or flow, water quality (natural or irretrievable human-induced conditions), substrate composition, or other habitat conditions. These waters are only capable of maintaining year-round populations of tolerant warmwater fish and associated vertebrate and invertebrate organisms and plants. Key species may be supported on a seasonal or intermittent basis (e.g., during high flows) but year-round populations cannot be maintained.

003.04D1 Dissolved Oxygen.

003.04D1a One-day minimum of not less than 5.0 mg/L for early-life stages. This criterion applies from April 1 through September 30.

003.04D1b One-day minimum of not less than 3.0 mg/L for all life stages other than early-life stages. This criterion applies from October 1 through March 31.

003.04D1c Seven-day mean minimum of not less than 4.0 mg/L. This criterion applies from October 1 through March 31.

003.04D1d Seven-day mean of not less than 6.0 mg/L for early-life stages. This criterion applies from April 1 through September 30.

003.04D1e Thirty-day mean of not less than 5.5 mg/L. This criterion applies from October 1 through March 31.

003.05 Nutrient Criteria for Lakes and Impounded Waters.

The following criteria associated with various nutrient classifications apply to lakes or impounded waters according to codes listed in Chapter 6. Criteria are based on seasonal averages from April 1 through September 30. Eastern Lakes and Impounded Waters are located within the Big Blue, Little Blue, Elkhorn, Lower Platte, Missouri Tributaries, and Nemaha River Basins. Western Lakes and Impounded Waters are located within the Loup, Middle Platte, Niobrara, North Platte, Republican, South Platte, and White River-Hat Creek Basins. Natural Sandhill Lakes are not subject to these criteria as they exist in a relatively undisturbed condition.

Chlorophyll a represents the desired biological condition (response) and is generally influenced by the amount of phosphorus and nitrogen (cause). Thus, if the chlorophyll a criterion is met, total phosphorus or total nitrogen values above the listed values will not be considered to violate their respective criteria.

004 Water Supply .

004.01 Public Drinking Water.

These are surface waters which serve as a public drinking water supply. These waters must be treated (e.g., coagulation, sedimentation, filtration, chlorination) before the water is suitable for human consumption. After treatment, these waters are suitable for drinking water, food processing, and similar uses.

004.01A General Criteria.

Wastes or toxic substances introduced directly or indirectly by human activity in concentrations that would degrade the use (i.e., would produce undesirable physiological effects in humans) will not be allowed.

004.01B Numerical Criteria.

Numerical criteria for the parameters listed below are not to be exceeded. Any substance introduced directly or indirectly by human activity is not to be allowed to enter surface water if one or more of the following numerical standards would be exceeded. The numerical standards listed below are intended to protect beneficial use of public drinking water supply. If the natural background level of a parameter is greater than the numerical standard, this will not in and of itself prohibit the use of the surface water. If the natural background level of a parameter is greater than the numerical standard listed below, the background level is to be used in place of the numerical criteria.

^a Human health criteria based on the consumption of water, fish and other aquatic organisms ^b Human health criteria at the 10-5 risk level for carcinogens based on the consumption of water, fish and other aquatic organisms ^c Primary Drinking Water MCL ^d Secondary Drinking Water Standard

004.02 Agricultural.

004.02A General Criteria.

Wastes or toxic substances introduced directly or indirectly by human activity in concentrations that would degrade the use (i.e., would produce undesirable physiological effects in crops or livestock) will not be allowed.

004.02B Class A - Agricultural.

These are waters used for general agricultural purposes (e.g., irrigation and livestock watering) without treatment.

004.02B1 Conductivity.

Not to exceed 2,000 umhos/cm between April 1 and September 30.

004.02B2 Nitrate and Nitrite as Nitrogen.

Not to exceed 100 mg/L.

004.02B3 Selenium.

Not to exceed 0.02 mg/L.

004.02C Class B - Agricultural.

These are waters where the natural background water quality limits its use for agricultural purposes. No water quality criteria are assigned to protect this use.

004.03 Industrial.

These are waters used for commercial or industrial purposes such as cooling water, hydroelectric power generation, or nonfood processing water; with or without treatment. Water quality criteria to protect this use will vary with the type of industry involved. Where water quality criteria are necessary to protect this use, site-specific criteria will be developed.

005 Aesthetics .

This use applies to all surface waters of the state. To be aesthetically acceptable, waters are to be free from human-induced pollution which causes: 1) noxious odors; 2) floating, suspended, colloidal, or settleable materials that produce objectionable films, colors, turbidity, or deposits; and 3) the occurrence of undesirable or nuisance aquatic life (e.g., algal blooms). Surface waters are also to be free of junk, refuse, and discarded dead animals.

Enabling Legislation: Neb. Rev. Stat. §81-1505(1)(2) Legal Citation: Title 117, Ch. 4, Nebraska Department of Environmental Quality

History

• Effective 2019-06-24

Chapter 5 Stream Classification by Basin

Neb. Admin. Code tit. 117, ch. 5 Stream Classification by Basin {#sec-117-nac-5 omnilex-key=us-ne-regs-official--title-117--117 NAC 5}

001 Beneficial uses are assigned to each designated segment in the basin tables. The water quality criteria in Chapter 4 associated with the assigned uses are applicable to each segment. These criteria are also applicable to segment tributaries, as necessary, to protect a segment's assigned uses if the tributary is not a designated segment. Assigned uses also apply to lakes and impounded waters located on designated segments unless those lakes or impounded waters are identified in Chapter 6. Lakes and impounded waters referenced in this Chapter are protected for beneficial uses as listed in Chapter 6.

002 The following species codes are used in the basin tables to identify the key species which typically occur in a stream segment.

003 The following basin tables show designated stream segments, assigned beneficial uses, and other stream classifications.

RIVER BASIN: Big Blue

Subbasin: BB1

RIVER BASIN: Big Blue

Subbasin: BB2

RIVER BASIN: Big Blue

Subbasin: BB3

RIVER BASIN: Big Blue

Subbasin: BB4

RIVER BASIN: Elkhorn

Subbasin: EL1

RIVER BASIN: Elkhorn

Subbasin: EL2

RIVER BASIN: Elkhorn

Subbasin: EL3

RIVER BASIN: Elkhorn

Subbasin: EL4

RIVER BASIN: Little Blue

Subbasin: LB1

RIVER BASIN: Little Blue

Subbasin: LB2

RIVER BASIN: Loup

Subbasin: LO1

RIVER BASIN: Loup

Subbasin: LO2

RIVER BASIN: Loup

Subbasin: LO3

RIVER BASIN: Loup

Subbasin: LO4

RIVER BASIN: Lower Platte

Subbasin: LP1

RIVER BASIN: Lower Platte

Subbasin: LP2

RIVER BASIN: Middle Platte

Subbasin: MP1

RIVER BASIN: Middle Platte

Subbasin: MP2

RIVER BASIN: Missouri Tributaries

Subbasin: MT1

RIVER BASIN: Missouri Tributaries

Subbasin: MT2

RIVER BASIN: Nemaha

Subbasin: NE 1

RIVER BASIN: Nemaha

Subbasin: NE2

RIVER Basin: Nemaha

Subbasin: NE3

RIVER BASIN: Niobrara

Subbasin: NI1

RIVER BASIN: Niobrara

Subbasin: NI2

RIVER BASIN: Niobrara

Subbasin: NI3

RIVER BASIN: Niobrara

Subbasin: NI4

RIVER BASIN: North Platte

Subbasin: NP1

RIVER BASIN: North Platte

Subbasin: NP2

RIVER BASIN: North Platte

Subbasin: NP3

RIVER BASIN: North Platte

Subbasin: NP3

RIVER BASIN: Republican

Subbasin: RE1

RIVER BASIN: Republican

Subbasin: RE2

RIVER BASIN: Republican

Subbasin: RE3

RIVER BASIN: South Platte

Subbasin: SP1

RIVER BASIN: South Platte

Subbasin: SP2

RIVER BASIN: White River-Hat Creek

Subbasin: WH1

RIVER BASIN: Whit River-Hat Creek

Subbasin: WH2

Enabling Legislation: Neb. Rev. Stat. §81-1505(1)(2)

Legal Citation: Title 117, Ch. 5, Nebraska Department of Environmental Quality

History

• Effective 2019-06-24

Chapter 6 Lakes and Impounded Waters

Neb. Admin. Code tit. 117, ch. 6 Lakes and Impounded Waters {#sec-117-nac-6 omnilex-key=us-ne-regs-official--title-117--117 NAC 6}

001 Lakes and impounded waters are classified by river basins. These waters are protected for the beneficial uses as assigned in paragraph 005.

002 Application of Standards to Lakes and Impoundments.

In lakes and impoundments, or portions thereof, which exhibit natural thermal stratification, all applicable narrative and numerical criteria, with the exception of the numerical criteria for temperature, apply only to the epilimnion. Numerical temperature criteria apply at all depths (epilimnion, metalimnion, and hypolimnion) of lakes and impoundments exhibiting natural thermal stratification. In lakes and impoundments, or portions thereof, not exhibiting natural thermal stratification, the applicable narrative and numerical criteria apply at all depths.

003 Management Procedures:

Areas listed in this Chapter may or may not be managed for swimming. The Department of Environmental Quality advises checking with the management agency or abiding by the Rules and Regulations posted in the area before using the water for recreational activities.

004 No point source discharge of wastewater from domestic, municipal, industrial, or livestock sources will be allowed directly into lakes or impounded waters except:

004.01 Wastewater from sources authorized by NPDES permits to discharge to these waters prior to May 10, 1982 which have operated under active NPDES permits since then.

004.02 Noncontact cooling waters from sources authorized by NPDES permits to discharge to these waters.

004.03 Stormwater from sources authorized by NPDES permits to discharge to these waters.

005 The following lakes and impounded waters are protected for the beneficial uses as noted in the tables below (SRA refers to State Recreation Area, WMA refers to Wildlife Management Area, SWA refers to State Wayside Area, NWR refers to National Wildlife Refuge).

RIVER BASIN: Big Blue

Subbasin: BB1 and BB2

RIVER BASIN: Big Blue

Subbasin: BB3 and BB4

RIVER BASIN: Elkhorn

Subbasin: EL1 and EL2

RIVER BASIN: Elkhorn

Subbasin: EL3 and EL4

RIVER BASIN: Little Blue

Subbasin: LB1 and LB2

RIVER BASIN: Loup

Subbasin: LO1

RIVER BASIN: Loup

Subbasin: LO2

RIVER BASIN: Loup

Subbasin: LO3 and LO4

RIVER BASIN: Lower Platte

Subbasin: LP1

RIVER BASIN: Lower Platte

Subbasin: LP1 and LP2

RIVER BASIN: Lower Platte

Subbasin: LP2

RIVER BASIN: Middle Platte

Subbasin: MP1 and MP2

RIVER BASIN: Middle Platte

Subbasin: MP2

RIVER BASIN: Missouri Tributaries

Subbasin: MT1

RIVER BASIN: Missouri Tributaries

Subbasin: MT1 and MT2

RIVER BASIN: Nemaha

Subbasin: NE1 and NE2

RIVER BASIN: Nemaha

Subbasin: NE2 and NE3

RIVER Basin: Niobrara

Subbasin: NI1, NI2, and NI3

RIVER BASIN: Niobrara

Subbasin: NI3

RIVER BASIN: Niobrara

Subbasin: NI3 and NI4

RIVER BASIN: North Platte

Subbasin: NP1 and NP2

RIVER BASIN: North Platte

Subbasin: NP2

RIVER BASIN: North Platte

Subbasin: NP3

RIVER BASIN: Republican

Subbasin: RE1, RE2, and RE3

RIVER BASIN: Republican

Subbasin: RE3

RIVER BASIN: South Platte

Subbasin: SP1 and SP2

RIVER BASIN: White River - Hat Creek

Subbasin: WH1

RIVER BASIN: White River - Hat Creek

Subbasin: WH1 and WH2

Enabling Legislation: Neb. Rev. Stat. §81-1505(1)(2)

Legal Citation: Title 117, Ch. 6, Nebraska Department of Environmental Quality

6-36

Effective Date: _______________

History

• Effective 2019-06-24

Chapter 7 Water Quality Standards for Wetlands

Neb. Admin. Code tit. 117, ch. 7 Water Quality Standards for Wetlands {#sec-117-nac-7 omnilex-key=us-ne-regs-official--title-117--117 NAC 7}

001 Wetlands serve a multitude of important functions which include, but are not limited to, providing habitat for aquatic life and other wildlife, food production, stormwater control and flood attenuation, erosion control, shoreline stabilization, nonpoint source runoff filtration, groundwater recharge, and aesthetics. Wetlands are characterized by extreme variations in hydrology, soils, vegetation, water quality, and biotic assemblages. The dynamic nature of wetlands requires standards which recognize their variability of natural water quality both through time at individual sites and between sites across the State. Wetland classifications, beneficial uses, and water quality criteria contained in this chapter reflect the unique characteristics of wetlands in Nebraska.

002 Application of Standards to Wetlands .

002.01 These standards apply to all natural wetlands and all artificial wetlands except as provided in paragraph 002.02. Numerical criteria which rely on water in order to be measured, will not be deemed applicable during periods when water is not present.

002.02 These standards do not apply to artificial wetlands constructed for the purpose of wastewater treatment, wastewater retention, or irrigation reuse. However, any discharge to surface waters from artificial wetlands constructed for these purposes is to meet the applicable standards for the receiving water.

002.03 Wastewater from domestic, municipal, or industrial sources authorized by NPDES permits to discharge to wetlands are to meet all applicable standards for the wetland. No mixing zones will be allowed within wetlands.

003 Wetland Classifications

Wetlands are classified into two categories based on hydrological characteristics which affect the attainable beneficial uses. For purposes of these standards, the two general classifications are surface-water overflow wetlands and isolated wetlands. Within each classification, specific wetland complexes and individual wetlands may be identified by their physical, chemical, and biological characteristics and functional values. Wetlands are defined in Chapter 1. Wetlands are identified and delineated using methods contained in the “Corps of Engineers Wetlands Delineation Manual,” Technical Report Y-87-1, U.S. Army Engineer Waterway Experiment Station, Vicksburg, MS.

003.01 Surface-Water Overflow Wetlands.

These are wetlands which exhibit a surface water connection to an adjacent stream or lake on a regular or periodic basis. These wetlands have the potential to provide beneficial uses identical to those of the adjacent stream or lake in addition to the beneficial uses recognized for wetlands (paragraph 004). These wetlands will be protected for the beneficial uses of the adjacent stream or lake as assigned in Chapters 5 or 6 in addition to those identified for wetlands. Water quality criteria associated with assigned beneficial uses of adjacent waterbodies (Chapter 4) apply to surface-water overflow wetlands in addition to criteria associated with wetland beneficial uses. When numerical criteria associated with wetland aquatic life beneficial uses differ with aquatic life criteria associated with the adjacent stream or lake, the more stringent criteria apply.

003.02 Isolated Wetlands.

These are wetlands which have no regular or periodic surface water connection to an adjacent stream or lake. The source of water for these wetlands may be either ground water or surface runoff. These wetlands will be protected for the beneficial uses recognized for wetlands (paragraph 004). Water quality criteria associated with wetland beneficial uses apply to isolated wetlands.

004 Beneficial Uses

Beneficial uses are assigned to wetlands within or bordering upon the State of Nebraska. Assigned beneficial uses are protected by the narrative and numerical water quality criteria listed or referenced in this chapter. Additionally, assigned and existing beneficial uses are protected by the Antidegradation Clause in Chapter 3. Some uses require higher quality water than others. When multiple uses are assigned to the same wetland, all assigned uses will be protected.

Beneficial uses assigned to all wetlands are:

Aquatic Life

Wildlife

Agricultural Water Supply

Aesthetics

These uses are not intended in any way to conflict with the quantitative beneficial uses provided for in Neb. Rev. Stat., Ch 46, regulating irrigation or the authority of the Nebraska Department of Natural Resources.

004.01 Aquatic Life

Wetlands assigned this beneficial use provide, or could provide, habitat capable of supporting aquatic biota on a regular or periodic basis. Aquatic biota are life forms which require water to fulfill basic life functions such as reproduction, growth, and development. Examples of aquatic biota include, but are not limited to, fish, macroinvertebrates, amphibians, and hydrophytic vegetation.

004.01A General Criteria

Water quality criteria are established to protect assigned beneficial uses. However, traditional water quality parameters in wetlands such as pH, temperature, dissolved oxygen, ammonia, chloride, and conductivity may naturally vary outside accepted ranges for other surface waters. Water quality criteria for specific wetlands or wetland complexes, except numerical criteria for toxic substances (paragraph 004.01C1), petroleum oil (paragraph 004.01D), and residual chlorine (paragraph 004.01F), are to be based on natural background values for traditional water quality parameters. However, these criteria are to be no more stringent than those associated with the Class B Warmwater Aquatic Life classification or the General Criteria for Aquatic Life of Chapter 4, Paragraphs 003.01A, 003.01B, 003.01G, and 003.04B.

004.01B Biological Criteria

The biological integrity of wetlands is to be maintained and protected. Any human activity causing water pollution which would significantly degrade the biological integrity of wetlands is a violation of these Standards. Upland soil and water conservation practices or normal farming, silviculture, and ranching activities involving tilling, seeding, cultivating, harvesting, and grazing for the production of food, fiber, and forest products, will not be considered to cause significant degradation of biological integrity in wetlands. However, the criteria in section 004.01C for toxic substances are applicable to wetlands where such toxic substances are the result of activities listed within this subsection.

004.01B1 Any human activity causing water pollution which would cause a significant adverse impact to an identified “key species” is a violation of these Standards.

004.01B1a Key Species

Key aquatic species are identified endangered or threatened species. The following list defines the aquatic species considered by the Department to be key species. In addition to this list, any key species listed in Chapter 5 for a waterbody adjacent to a surface-water overflow wetland will be considered a key species for the wetland.

004.01C Toxic Substances

Wetlands are to be free from toxic substances, alone or in combination with other substances, in concentrations that result in acute or chronic toxicity to aquatic life, except as specified in Chapter 2. Toxic substances are not to be present in concentrations that result in bioaccumulation or biomagnification in aquatic organisms which renders them unsuitable or unsafe for consumption.

004.01C1 Criteria for the protection of aquatic life and their uses are found in Title 117, Chapter 4, 003.01C1 with the exception of the following. These criteria are not to be exceeded. Unless otherwise noted, criteria are based on total concentrations.

^aOne-hour average concentration ^bFour-day average concentration

¹ Criteria for metals and inorganics apply to dissolved concentrations ² The conversion factors for cadmium are hardness dependent and defined by:

ACF = 1.136672-[ln hardness (0.041838)] CCF = 1.101672-[ln hardness (0.041838)]

004.01C2 The following criteria for the protection of human health based on consumption of fish and other aquatic organisms are not to be exceeded. These criteria are expressed as fish tissue concentrations (mg/kg fish).

• Chemical Abstract Services Registry Number

004.01C3 The following Selenium criteria are for the protection of aquatic life. These criteria are expressed preferentially as fish tissue concentrations (mg/kg fish), followed by water column concentrations (mg/L) in the absence of fish tissue information.

^1. Fish tissue elements are expressed as steady-state. ^2. Egg/Ovary supersedes any whole-body, muscle, or water column element when fish egg/ovary concentrations are measured. ^3. Fish whole-body or muscle tissue supersedes water column element when both fish tissue and water column concentrations are measured. ^4. Water column values are based on dissolved total selenium in water and are derived from fish tissue values via bioaccumulation modeling. Water column values are the applicable criterion element in the absence of steady-state condition fish tissue data. ⁵. Where WQC30-day is the water column monthly element, for either a lake or stream; Cbkgrnd is the average background selenium concentration, and ƒint is the fraction of any 30-day period during which elevated selenium concentrations occur, with ƒint assigned a value ≥0.033 (corresponding to 1 day). ^6. Fish tissue data provide instantaneous point measurements that reflect integrative accumulation of selenium over time and space in fish populations at a given site.

• Chemical Abstract Services Registry Number

004.01D Petroleum Oil.

Not to exceed 10 mg/L.

004.01E Alkalinity

No less than 20 mg/L as CaCO3 except where natural background is less.

004.01F Residual Chlorine

004.01F1 One-hour average concentration not to exceed 19 μg/L.

004.01F2 Four-day average concentration not to exceed 11 μg/L.

004.02 Wildlife

Wetlands assigned this beneficial use provide, or could provide, habitat capable of supporting wildlife on a regular or periodic basis. Wildlife are undomesticated terrestrial or avian life forms which may utilize wetlands to support life functions such as watering, feeding, loafing, predator protection, and nesting. Examples of wildlife include, but are not limited to, furbearers, waterfowl, shorebirds, migratory birds, and reptiles.

004.02A General Criteria

Because wildlife utilizing wetlands rely on aquatic biota in many cases for food and habitat, general criteria and toxic criteria listed for the protection of aquatic life (paragraphs 004.01A and 004.01C) also apply for the protection of wildlife.

004.02B Biological Criteria

Any human activity causing water pollution which would cause a significant adverse impact to an identified “key species” is a violation of these Standards.

004.02B1 Key Species

Key wildlife species are identified endangered, threatened, or sensitive species. The following list defines the wildlife species considered by the Department to be key species.

004.03 Agricultural Water Supply

Wetlands assigned this beneficial use are used or have the potential to be used for general agricultural purposes (e.g., irrigation and livestock watering) without treatment. In some cases, however, natural background water quality may limit their use for agricultural purposes.

004.03A General Criteria

Wastes or toxic substances introduced directly or indirectly by human activity in concentrations that would degrade the use (i.e., would produce undesirable physiological effects in crops or livestock) will not be allowed. Where natural background water quality limits the use of a wetland for agricultural purposes, water quality criteria for conductivity and selenium are to be based on the natural background condition.

004.03B Conductivity.

Not to exceed 2,000 umhos/cm between April 1 and September 30.

004.03C Nitrate and Nitrite as Nitrogen.

Not to exceed 100 mg/L.

004.03D Selenium.

Not to exceed 0.02mg/L.

004.04 Aesthetics.

This use applies to all wetlands of the state. To be aesthetically acceptable, wetlands are to be free from human-induced pollution which causes: 1) noxious odors; 2) floating, suspended, colloidal, or settleable materials that produce objectionable films, colors, turbidity, or deposits; and 3) the occurrence of undesirable or nuisance aquatic life (e.g., algal blooms). Wetlands are also to be free of junk, refuse, and discarded dead animals.

Enabling Legislation: Neb. Rev. Stat. §§ 81-1501(1) and 81-1505(1)(2)

Legal Citation: Title 117, Ch. 7, Nebraska Department of Environmental Quality

History

• Effective 2019-06-24