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Delaware General AssemblyDelaware RegulationsMonthly Register of RegulationsOctober 2014

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7 DE Admin. Code 7401
Under the authority vested in the Secretary of the Department of Natural Resources and Environmental Control ("Department" or "DNREC") under 29 Del.C. §8001 et seq., 29 Del.C. §10111 et seq. and 7 Del.C. §6010(a), the following findings, reasons and conclusions are entered as an Order of the Secretary to amend the regulation, 7 DE Admin. Code 7401, Surface Water Quality Standards. (Regulation 7401). The attached Hearing Officer's Report (Report) reviews the record and recommends approval of the proposed amendment. The Report is adopted to the extent it is consistent with this Order.
6. The Department's proposed amendment to Regulation 7401, as published in the April 1, 2014, Delaware Register of Regulations, and as set forth in Appendix A to the Report, is well supported by the record, and is reasonable to regulate water quality consistent with the applicable laws and regulations.
7. The Department shall have published this Order in the Delaware Register of Regulations; and the notice in newspapers, and the Regulation amendment will go into effect ten days after its publication in the Delaware Register of Regulations.
“Acute” means involving a stimulus severe enough to rapidly induce an adverse response; in toxicity tests, an adverse response observed in 96 hours or less is typically considered acute. An acute effect is not always measured in terms of lethality; it can measure a variety of short term adverse effects.
“Additive Effect” means the total effect of a mixture of pollutants which is equal to the arithmetic sum of the effects of the individual pollutants in the mixture.
“Agriculture” means the use of land and water in the production of food, fiber and timber products.
“Antagonistic Effect” means the total effect of a mixture of pollutants which is less than the arithmetic sum of the effects of the individual pollutants in the mixture.
“Average” means, unless otherwise noted, the arithmetic mean of a representative group of samples for a specified parameter. Representativeness shall be determined through application of appropriate statistical techniques to data collected at times of critical ambient conditions, as determined on a parameter-by-parameter basis.
“Best Management Practice (BMP)” are methods, measures or practices that are determined by the Department to be reasonable and cost-effective means for a person to meet certain, generally nonpoint source, pollution control needs. BMPs include but are not limited to structural and nonstructural controls and operation and maintenance procedures. BMPs can be applied before, during or after pollution-producing activities to reduce or eliminate the introduction of pollutants into receiving waters.
“Best Scientific Judgment” means findings, conclusions, or recommended actions which result from the application of logical reasoning and appropriate scientific principles and practices to available and relevant information on a particular situation.
“Bioavailability” means a measure of the physicochemical access of a pollutant to an organism.
“Biodegradation” means the biological decomposition of natural or synthetic organic materials by microorganisms.
“Carcinogen” means a substance that increases the risk of benign or malignant neoplasms (tumors) in humans or other animals. Carcinogens regulated through these Standards include but may not be limited to those toxic substances classified as Group A or Group B carcinogens as defined in 51 FR 185 (9/24/86).
“Chronic” means involving a stimulus that produces an adverse response that lingers or continues for a relatively long period of time, often one-tenth of the life span or more. Chronic should be considered a relative term depending on the life span of the organism. A chronic effect can be lethality, growth or reproductive impairment, or other longer term adverse effect.
“Clean Water Act” means 33 U.S.C. 1251 et. seq., as amended.
“Cold Water Fish Use” means protection of fish species (such as from the family Salmonidae) and other flora and fauna indigenous to a cold water habitat.
“Complete Mix” means the concentration of a discharged pollutant varies by no more than 5% over the cross-sectional area of the receiving water at the point of discharge.
“Conservation Plan” means a conservation plan is a record of land user decisions affecting land use and conservation treatment of natural resources including soil, water, air, plant, and animal resources. It is comprised of resource management systems which are groups of interrelated conservation practices (BMPs) and management measures formulated to protect, restore, or improve the resource base. Conservation plans are usually developed with the assistance of conservation districts using district BMP standards (ref: Field Office Technical Guide, USDA Soil Conservation Service).
“Control Structure” means a dam, weir or other structure placed by man to regulate stream flow and/or create an impoundment.
“Critical Flow” means a statistically determined minimum flow, which has a defined duration and recurrence interval.
“Degradation” means any adverse change in water quality or existing uses.
“Department” means the Delaware Department of Natural Resources and Environmental Control.
“Designated Uses” means those uses specified in water quality standards for each water body or segment whether or not they are being attained.
“Diadromous” describes fish which migrate to and from marine water and freshwater for the purpose of spawning.
“Discharge Length Scale” means the square root of the cross-sectional area of any discharge outlet.
“Dispersion” means a physical mixing process which results in the scattering of particles or dissolved materials in the water column.
“Early Life Stages” means life stages for fish which include all embryonic and larval stages, and all juvenile forms to 30 days following hatching.
“Ephemeral” describes a stream which contains flowing water only for short periods following precipitation events.
“Excavated Waters” means waters of the State which are wholly human-created. Such waters shall include but not be limited to upland basins with surface outlets, drainage and tax ditches which are ephemeral, and dug ponds.
“Existing Use” means those uses actually attained in the water body on or after November 28, 1975, whether or not they are included in the water quality standards.
“Fish, Aquatic Life And Wildlife” means all animal and plant life found in Delaware, either indigenous or migratory, regardless of life stage or economic importance.
“Foam” means frothy, generally stable, whitish mass of bubbles formed on or in the water upon agitation of the water.
Fresh Water” means waters of the State which contain natural levels of salinity of 5 parts per thousand or less.
Fresh Water Flow” means that flow which represents the amount of water passing a measurement point in a non-tidal system.
“Harvestable Shellfish Waters” means waters from which shellfish may be taken and consumed; such waters are approved for shellfish harvesting by the [State Board of Health Shellfish & Recreational Waters Branch, Watershed Assessment and Management Section, Division of Watershed Stewardship, Department of Natural Resources and Environmental Control].
“Hydrolysis” means a reaction of a chemical with water which results in the cleavage of a chemical bond.
“Indigenous” means native, or naturally growing, existing, or produced.
“Industrial Water Supply” means any water that is protected for use for industrial purposes, including non-contact cooling water.
“Intake Water” means water used by a facility from surface water, groundwater, commercial, or other sources.
“Intermittent” describes a stream which contains flowing water for extended periods during a year, but does not carry flow at all times.
“Lethal Concentration (LC)” means the point estimate of the toxicant concentration that would be lethal to a given percentage of test organisms during a specific period.
“Marine Water” mean waters of the State which contain natural levels of salinity in excess of 5 parts per thousand.
“Migratory Fish Spawning and Nursery Designated Use” means in the Nanticoke River from the upstream-most limits of the City of Seaford to the Maryland State Line and the Broad Creek from the upstream-most limits of the Town of Laurel to the confluence with the Nanticoke River, the survival, growth and propagation of balanced indigenous populations of ecologically, recreationally and commercially important anadromous, semi-anadromous and tidal-fresh resident fish inhabiting spawning and nursery grounds from February 1 through May 31
“Minimum Analytical Level” mean the lowest concentration of a substance that can be quantified within specified limits of interlaboratory precision and accuracy under routine laboratory operating conditions in the matrix of concern.
“NPDES” means National Pollutant Discharge Elimination System as provided in the Clean Water Act.
“Natural Conditions” means water quality characteristics found or expected in the absence of human-induced pollution due to point or nonpoint sources.
“Net Advective Flow” is that flow which represents the difference between the amount of water passing a point in a tidal system on a flood tide and the subsequent ebb tide. It is approximately equal to the freshwater input to the system upstream of that point.
“Normal Corrosion” means an ectrochemical reaction that results in the dissolution or removal of metal from a solid metal surface. For specific applications considered by the Department, normal corrosion rates shall be as published by the National Association of Corrosion Engineers (Reference: Corrosion Data Survey - Metals Section, National Association of Corrosion Engineers, 1985, as updated from time to time) or, for applications not specifically addressed in the above reference, such other reliable data.
“Normal Erosion” means the progressive loss of original material from a solid surface due to mechanical interaction between that surface and a fluid, a multi-component fluid or an impinging liquid or solid particle. (Reference: Standard Practice for Liquid Impingement Erosion Testing, ASTM Designation G73-82, 1987; or other authoritative source for materials or conditions not covered by the referenced standard).
“Nuisance Condition” means any condition that, as a result of pollutant addition to a stream, causes unreasonable interference with the designated uses of the waters or the uses of the adjoining land areas.
“Nuisance Species” mean any species of fish, other animal, or plant living in or near the water, the presence of which causes unreasonable interference with the designated uses of the waters or the uses of adjoining land areas. Nuisance species include but are not limited to filamentous and blue-green algae.
“Nutrient” means any element or compound essential as a raw material for organism growth and development, including but not limited to nitrogen and phosphorus.
“One-hour Average” means the arithmetic average of the samples collected during a continuous one-hour period.
“Open-water Fish And Shellfish Designated Use” means in the Nanticoke River from the upstream-most limits of the City of Seaford to the Maryland State Line and the Broad Creek from the upstream-most limits of the Town of Laurel to the confluence with the Nanticoke River, the survival, growth and propagation of balanced indigenous populations of ecologically, recreationally and commercially important fish and shellfish inhabiting open water habitats year round
“Overenrichment” means excessive addition of nutrients to a water body, resulting in deterioration of designated uses of the waters.
“Perennial” describes a freshwater stream which contains flowing water at all times.
“Person” means any individual, trust, firm, joint stock company, federal agency, partnership, corporation (including a government corporation), association, state, municipality, commission, political subdivision of a state, or any interstate body.
“Photolysis” means a light-catalyzed degradation reaction that occurs when light strikes certain chemicals.
“Pollutant” means 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, hydrocarbons, oil and product chemicals, and industrial, municipal, and agricultural waste discharged into water.
“Practicable” means available and capable of being done after taking into consideration cost and existing technology, as well as logistics in light of overall facility operations or project purposes.
“Primary Contact Recreation” means any water-based form of recreation, the practice of which has a high probability for total body immersion or ingestion of water (examples include but are not limited to swimming and water skiing).
“Propagation” means reproduction of fish, aquatic life and wildlife within their natural environment.
“Public Water Supply” means any waters of the State designated as public water supply in Section 10.
Regulatory Mixing Zone: A designated, mathematically defined portion of a receiving water body, in close proximity to a discharge, in which initial dilution, dispersion, and reaction of discharged pollutants occur. See Section 6 for details on use of term.
“Risk Management Level” means that level above which an assessed risk is unacceptable from a public health perspective.
“Scientifically Reasonable Request” means any request that is based upon material, substantial, and relevant information and would be accepted as reasonable by most persons trained and competent in the subject of the request.
“Scum” describes a thin layer of impurities which forms on the surface of waters of the State.
“Secondary Contact Recreation” means a water-based form of recreation, the practice of which has a low probability for total body immersion or ingestion of water (examples include but are not limited to wading, boating, and fishing).
“Sedimentation” means the movement of solid particles and adsorbed chemicals toward the bottom of the water column under the influence of gravity.
“Shallow-water Bay Grass Designated Use” means in the Nanticoke River from the upstream-most limits of the City of Seaford to the Maryland State Line and the Broad Creek from the upstream-most limits of the Town of Laurel to the confluence with the Nanticoke River, the survival, growth and propagation of rooted, underwater bay grasses necessary for the propagation and growth of balanced indigenous populations of ecologically, recreationally and commercially important fish and shellfish inhabiting vegetated shallow-water habitats April 1 through October 31
Shellfish” means any species of fresh, brackish or salt water mollusk that is commonly considered to be edible. Typical edible mollusks include but are not limited to clams, mussels, oysters, scallops, and whelks.
“Stream Basin” means a specified drainage area from which (in most cases) all waters exit through a single outlet.
“Surface Water” means water occurring generally on the surface of the earth.
“Synergistic Effect” means the total effect of a mixture of pollutants which is greater than the arithmetic sum of the effects of the individual pollutants in the mixture.
“Systemic Toxicant” means a toxic substance that has the ability to cause health effects within the body at sites distant from the entry point due to its absorption and distribution. Systemic toxicants are believed to have threshold concentrations or levels below which no health effects occur.
“Tidal” means surface waters characterized by periodic rise and fall due to gravitational interactions between the sun, moon, and earth.
“Toxic Substance” means any substance or combination of substances including disease-causing agents, which after discharge and upon exposure, ingestion, inhalation, or assimilation into any organism, either directly from the environment or indirectly by ingestion through food chains, may cause death, disease, behavioral abnormalities, cancer, genetic mutations, physiological malfunctions (including malfunctions in reproduction), or physical deformities in such organisms or their offspring.
“Toxicity” means the ability to cause death, disease, behavioral abnormalities, cancer, genetic mutations, physiological malfunctions (including malfunctions in reproduction), or physical deformities in organisms or their offspring.
“Toxicity Test” is the means to determine the toxicity of a chemical or effluent using living organisms. A toxicity test measures the degree of response of an exposed test organism to a specific chemical or effluent.
“True Daily Mean” is the mean value for a parameter which accurately accounts for diurnal variations over one 24-hour period.
Use Attainability Analysis” means a structured scientific assessment of the factors affecting the attainment of the use which may include physical, chemical, biological, and economic factors as described in Sections 9.1.1.1 though 9.1.1.8).
“Volatilization” means the loss of a chemical from the water column due to mass exchange across the air-water interface.
“Water Distribution Piping and Appurtenances” means pipes and piping systems, along with integral components thereof, which are used to convey water from one point to another.
“Water Pollution” means man-made or human-induced alteration of the chemical, physical, biological or radiological integrity of surface waters of the State.
Waters of the State” means:
“Water Quality” mean the physical, chemical, and biological characteristics of water with respect to its suitability for a particular use. For the purposes of these Standards, water quality shall be assessed in terms of chemical composition, biological integrity, and physical habitat.
“Water-Quality Based” generally refers to requirements for pollution control that are in excess of technology-based minimum requirements, including but not limited to those listed in Sections 301(b) and 306 of the Clean Water Act. Such controls are designed to reduce pollutants to a level that will allow water quality standards to be attained where said standards would not be attained through application of the technology-based controls.
“Water Quality Criterion” means an element of water quality standards, expressed as constituent concentrations, levels, or narrative statements, representing a quality of water that supports a particular designated use.
“Water Quality Standard” means a rule or limit defined herein which consists of a designated use or uses for waters of the State and water quality criteria for such waters based upon such designated uses.
["Wetland Dominated Tidal River Designated Use" applies to the Murderkill River from the Route 1 Bridge to the confluence with Delaware Bay which supports the survival, growth and propagation of balanced indigenous populations of fish inhabiting the river and adapted to intermittent low dissolved oxygen caused by natural processes during the period May 16 through September 30.]
Wetlands” means wetlands are those areas that are inundated or saturated by surface or ground water 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.
x [(r)]
x-
Figure 1 Delaware Watersheds and Waterbodies
4.5.1.2.1 Maximum increase above natural conditions shall be 4 oF from October through May. Temperature rise during June through September shall be limited by the following conditions:
4.5.2.5 All Waters The Murderkill River from the Route 1 Bridge to the Confluence with the Delaware Bay
4.5.2.5.1 In cases where natural conditions prevent attainment of these criteria, allowable reduction in dissolved oxygen levels as a result of human activities shall be determined through application of the requirements of Sections 5 and 9 of these Standards. For the period from May [15 16] through September 30:
4.5.2.5.1.2 [Instantaneous One Hour] Minimum: one hour average shall not be less than 1.0 mg/L
4.5.2.5.2 The Department may mandate additional limitations on a site-specific or seasonal basis in order to provide incremental protection for early life stages of fish. For the period October 1 through [April 30 May 15], applicable criteria for all waters of the State shall apply.
4.5.6 Water Clarity in the The Nanticoke River from the upstream-most limits of the City of Seaford to the Maryland State Line and Broad Creek from the upstream-most limits of the Town of Laurel to the confluence with the Nanticoke River:
4.5.6.1 Chlorophyll-a criteria for the Nanticoke River from the upstream-most limits of the City of Seaford to the Maryland State Line and Broad Creek from the upstream-most limits of the Town of Laurel to the confluence with the Nanticoke River:
Concentrations of chlorophyll-a in free-floating microscopic aquatic plants (algae) shall not exceed levels that result in ecologically undesirable consequences - such as reduced water clarity, low dissolved oxygen, food supply imbalances, proliferation of species deemed potentially harmful to aquatic life or humans or aesthetically objectionable conditions or otherwise render tidal waters unsuitable for designated uses.
4.5.9.3.2.1 Water quality criteria appearing in Table 2 for pollutants identified as carcinogens have been established at an upper bound worst case risk management level of one excess cancer in a population of one million (1 x 10-6) over a 70 year lifetime. Criteria listed under the columns header "Fish and Water Ingestion" apply only to surface waters of the State designated as Public Water Supply Sources in Section 3 of these Standards. Criteria listed under columns headed "Fish Ingestion Only" apply to all surface waters of the State not designated as Public Water Supply Sources in Section 3 of these Standards.
(1.136672-LN(hardness)*0.041838)* EXP(1.0166*LN(hardness)-3.924)
(1.101672-LN(hardness)*0.041838)* EXP(0.7409*LN(hardness)-4.719)
0.316*EXP(0.819*LN(hardness)+3.7256)
0.86*EXP(0.819*LN(hardness)+0.6848)
0.96*EXP(0.9422*LN(hardness)-1.7) Freshwater criteria calculated using the EPA Biotic Ligand Model
0.96*EXP(0.8545*LN(hardness)-1.702) Freshwater criteria calculated using the EPA Biotic Ligand Model
(1.46203-LN(hardness)*0.145712)* EXP(1.273*LN(hardness)-1.460)
(1.46203-LN(hardness)*0.145712)* EXP(1.273*LN(hardness)-4.705)
0.998*EXP(0.8460*LN(hardness)+2.255)
0.997*EXP(0.8460*LN(hardness)+0.0584)
EXP(1.005*pH-4.869)
EXP(1.005*pH-5.134)
0.85*EXP(1.72*LN(hardness)-6.59)
0.978*EXP(0.8473*LN(hardness)+0.884)
0.986*EXP(0.8473*LN(hardness)+0.884)
1Cyanide measured as free cyanide at the lowest pH occurring in the receiving water, or cyanide amenable to chlorination.
1 + 107.204-pH 1 + 10pH-7.204
1 + 107.204-pH 1 + 10pH-7.204
1 + 107.688-pH 1 + 10pH-7.688
1 + 107.688-pH 1 + 10pH-7.688
150 850
1.6 3.0
0.23 0.43
80000 2400
200 21
260000 27000
590 2200
4.6 17
0.00003 (MCL) .0000005
46 32
20 14
3.3 1.1
1.4 0.5
690 2800
17 68
11000 1800
3 0.9
0.27 0.08
1300 780
3.3 62
0.69 13
30 8.2
2.5 0.7
Values shown with “(MCL)” under header "Fish and Water Ingestion" are Primary Maximum Contaminant Levels (MCLs) as given in the State of Delaware Regulations Governing Public Drinking Water Systems that became effective September 10, 2001
[1 Criteria is for the "total toxic equivalence (TEQ) to 2, 3, 7, 8 - TCDD". The toxic equivalence for a sample is the sum of the concentration for each congener multiplied by its associated Toxicity Equivalence Factor (TEF) listed in table below.