DEPARTMENT OF NATURAL RESOURCES AND ENVIRONMENTAL CONTROL
Division of Water Resources
Statutory Authority: 7 Delaware Code, Section 6010 (7 Del.C. §6010)
7 DE Admin. Code 7401
 
FINAL
 
Secretary’s Amended and Superseding Order 2010-W-0035
Date of Issuance: May 17, 2011
Effective Date of the Amendment: June 11, 2011
 
7401 Surface Water Quality Standards
 
Under the authority vested in the Secretary of the Department of Natural Resources and Environmental Control (“Department” or “DNREC”) under Chapter 60 and the State of Delaware Surface Water Quality Standards (as amended July 11, 2004), the following findings, reasons and conclusions are entered as an Amended and Superseding Order of the Secretary in the above-referenced rulemaking proceeding.
Whereas, Secretary’s Order No. 2010-W-0035 (the “Original Order”) was signed by Secretary O’Mara on November 9, 2010, and forwarded to the State of Delaware Register of Regulations for publication in the December 1, 2010 Register. The Original Order recommended that the Department’s proposed Amendments should be adopted as final regulations because Delaware would then be enabled to (1) ensure compliance with the federal Clean Water Act and will satisfy EPA requirements; and would then be able to (2) retain its ability to perform site-specific studies on inorganic arsenic in fish and shellfish when warranted, and to issue public health advisories when and where appropriate, to not only reduce the public’s exposure to inorganic arsenic, but to also provide the means to justify water quality based controls. Moreover, the regulation amendments were well supported by documents in the record; and
Whereas, subsequent to the Department forwarding the Original Order to the Delaware Register of Regulations, it was realized that the entire promulgation process involved with this particular action had been pending for over 12 months, with the public hearing having been held on September 2, 2009. Pursuant to 29 Del.C., §10118(f) , “No agency shall adopt a regulation if more than 12 months have elapsed since the end of the public comment period or the last public hearing, whichever is later, on the proposed regulation.”; and
Whereas, in order to correct the record in this matter and have this promulgation be compliant with 29 Del.C., §10118(f) as noted above, the Department re-opened the comment period to the public for additional comments on the proposed Amendments to the State of Delaware Surface Water Quality Standards (as amended July 11, 2004) for a period of 30 days, beginning on March 1, 2011, and ending at close of business on April 1, 2011. Accordingly, the Department published a formal notice of the re-opening of this record in the Delaware Register of Regulations, and made all information (i.e., the proposed regulation and all supporting documents) available for review once again on the Department’s website; and
Whereas, on April 14, 2011, the Watershed Assessment Section of the Department provided an email to Hearing Officer Lisa A. Vest, which confirmed that the Department had received no additional comments whatsoever on the proposed Amendments to the State of Delaware Surface Water Quality Standards during the aforementioned 30 day period (from March 1, 2011 through April 1, 2011); and
Whereas, given the fact that no additional comment was received by the Department during the aforementioned 30 day period, no changes have been made to the proposed regulatory language as set forth previously in the August 1, 2009 Delaware Register of Regulations; and
Therefore, the Original Order is hereby amended and superseded by this revised Order, so as to reflect the correction of the record by the re-opening of the record to include an additional 30-day comment period as noted above, thereby making this promulgation compliant with 29 Del.C., §10118(f) as noted above.
 
Background and Procedural History
 
This Order considers the proposed regulatory amendments to 7 DE Admin. Code 7401, State of Delaware Surface Water Quality Standards. The purpose of this regulatory action is to ensure federal compliance with the Clean Water Act, and to satisfy current EPA requirements regarding same. It is the policy of the Department to maintain within its jurisdiction surface waters of the State of Delaware of satisfactory quality, consistent with public health and public recreation purposes, the propagation and protection of fish and aquatic life, and other beneficial uses of the water. Where conflicts develop between stated surface water uses, stream criteria, or discharge criteria, designated uses for each segment are paramount in determining the required stream criteria, which, in turn, become the basis of specific discharge limits or other necessary controls. Additionally, where existing facilities operating under a permit from this Department are required to reduce pollution concentrations or loadings due to the implementation of these Standards, a reasonable schedule for compliance may be granted by DNREC, in accordance with standards or requirements established in applicable statutes and regulations. It is also the intent of the Department, in accordance with these Standards, to develop an agency-wide program to assess, manage, and communicate human health cancer risks from the major categories of environmental pollution under its jurisdiction.
The aforementioned proposed amendments to Delaware’s existing Surface Water Quality Standards are the result of an exhaustive and comprehensive triennial review that started with DNREC Start Action Notice #2008-24, approved by the Secretary on October 29, 2008. The Department published the proposed regulatory amendments in the August 1, 2009 Delaware Register of Regulation and held a public hearing on September 2, 2009. The Department’s presiding hearing officer, Lisa A. Vest, prepared a Hearing Officer’s Report dated October 12, 2010 (Report). The Report recommends certain findings and the adoption of the proposed Amendments as attached to the Report as Appendix A.
Subsequently, in order to correct the record in this matter and have this promulgation be compliant with 29 Del.C., §10118(f) as noted above, the Department re-opened the comment period to the public for additional comments on the proposed Amendments to the State of Delaware Surface Water Quality Standards (as amended July 11, 2004) for a period of 30 days, beginning on March 1, 2011, and ending at close of business on April 1, 2011. On April 14, 2011, the Watershed Assessment Section of the Department provided an email to Hearing Officer Lisa A. Vest, which confirmed that the Department had received no additional comments whatsoever on the proposed Amendments to the State of Delaware Surface Water Quality Standards during the aforementioned 30 day period, and therefore no changes have been made to the proposed regulatory language as set forth previously in the August 1, 2009 Delaware Register of Regulations.
 
Findings and Discussion
 
I find that the proposed Amendments are well-supported by the record developed by the Department, and adopt the Report to the extent it is consistent with this Order. The Department’s experts developed the record and drafted the proposed Amendments. Throughout the entire regulatory development process regarding this promulgation, the Department received public comment, as noted in the Report, and considered and responded to all timely and relevant public comments in making its determination.
I find that the Department’s experts in the Watershed Assessment Section of the Division of Watershed Stewardship fully developed the record to support adoption of these Amendments. With the adoption of the regulation amendments to 7 DE Admin. Code 7401, State of Delaware Surface Water Quality Standards, Delaware will be able to ensure compliance with the federal Clean Water Act and will satisfy EPA requirements.
In conclusion, the following findings and conclusions are entered:
1.) The Department has jurisdiction under its statutory authority to issue an Order adopting these proposed Amendments as final;
2.) The Department provided adequate public notice of the proposed Amendments, and provided the public with an adequate opportunity to comment on the proposed Amendments, including at a public hearing;
3.) The Department held a public hearing on September 2, 2009 on the proposed Amendments in order to consider public comments before making any final decision, and fully considered and responded to all timely and relevant comments received from the regulated community concerning this matter;
4) The Department’s Hearing Officer’s Report, including its recommended record and the recommended Amendment as set forth in Appendix A, are adopted to provide additional reasons and findings for this Order;
5.) The recommended Amendments do not reflect any substantive change from the proposed regulation Amendment as published in the August 1, 2009, Delaware Register of Regulations;
6.) The recommended Amendments should be adopted as final regulation Amendments because Delaware will then be enabled to (1) ensure compliance with the federal Clean Water Act and will satisfy EPA requirements; and will (2) retain its ability to perform site-specific studies on inorganic arsenic in fish and shellfish when warranted, and to issue public health advisories when and where appropriate, to not only reduce the public’s exposure to inorganic arsenic, but to also provide the means to justify water quality based controls. Moreover, the regulation amendments are well supported by documents in the record; and
7.) The Department shall submit this Order approving the final regulation to the Delaware Register of Regulations for publication in its next available issue, and provide such other notice as the law and regulation require and the Department determines is appropriate.
Collin P. O’Mara, Secretary
 
7401 Surface Water Quality Standards
 
1.0 Intent
1.1 It is the policy of the Department to maintain within its jurisdiction surface waters of the State of satisfactory quality consistent with public health and public recreation purposes, the propagation and protection of fish and aquatic life, and other beneficial uses of the water.
1.2 Where conflicts develop between stated surface water uses, stream criteria, or discharge criteria, designated uses for each segment shall be paramount in determining the required stream criteria, which, in turn, shall be the basis of specific discharge limits or other necessary controls.
1.3 Where existing facilities operating under a permit from this Department are required to reduce pollution concentrations or loadings due to the implementation of these surface water quality standards, a reasonable schedule for compliance may be granted in accordance with standards or requirements established in applicable statutes and regulations.
1.4 The Department intends to develop an agency-wide program to assess, manage, and communicate human health cancer risks from the major categories of environmental pollution under its jurisdiction. As a result of this activity, it may be necessary to adjust the upper bound worst case risk management level stated in Section 4.5.9.3.2.1 4.6.3.3.2.1.
 
2.0 Definitions
The following words and terms, when used in this regulation, shall have the following meaning unless the context clearly indicates otherwise:
“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.
“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 through 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:
All surface waters of the State including but not limited to:
Waters which are subject to the ebb and flow of the tide, including but not limited to estuaries, bays, and the Atlantic Ocean;
All interstate waters, including interstate wetlands;
All other waters of the State, such as lakes, rivers, streams (including intermittent and ephemeral streams), drainage ditches, tax ditches, creeks, mudflats, sandflats, wetlands, sloughs, or natural or impounded ponds;
All impoundments of waters otherwise defined as waters of the State under this definition;
Wetlands adjacent to waters (other than waters that are themselves wetlands) identified above;
Waste and stormwater treatment systems, including but not limited to treatment ponds or lagoons designed to meet the requirements of the Clean Water Act (other than cooling ponds which otherwise meet the requirements of subsection (l) of this definition) are not waters of the State.
Waters of exceptional recreational or ecological significance (ERES): Waters which are important, unique, or sensitive from a recreational and/or ecological perspective, but which may or may not have excellent water quality. Such waters shall normally have regional significance with respect to recreational use (fishing, swimming and boating), or have significant or widespread riverine, riparian, or wetland natural areas.
“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.
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.
 
3.0 Stream Basins & Designated Uses
The designated uses applicable to the various stream basins represent the categories of beneficial use of waters of the state which must be maintained and protected through application of appropriate criteria.
 
Public Water Supply Source
Cold Water Fish (Put-and-Take)
Harvestable Shellfish Waters
x-
 
(a) Designated use for freshwater segments only.
(b) Designated use from March 15 to June 30 on:
1. Beaver Run from PA/DE line to Brandywine.
2. Wilson Run Route 92 through Brandywine Creek State Park.
(c) Designated use from March 15 to June 30 on:
1. Christina River from MD/DE line through Rittenhouse Park.
(d) Designated use for marine water segments only.
(e) Designated use year round on:
1. Red Clay Creek from PA/DE line to the concrete bridge above Yorklyn
(f) Designated use year round on:
1. White Clay Creek from the PA/DE line to the dam at Curtis Paper.
Designated use from March 15 to June 30 on:
2. Mill Creek from Brackenville Road to Route 7.
3. Pike Creek from Route 72 to Henderson Road.
(g) Designated use from PA/DE line to the dam at Curtis Paper.
(h) Designated use from PA/DE line to Wilmington city line.
(i) Goal use - not currently attained.
(j) Parts of these waters are APPROVED shellfish harvesting areas. Information on areas where shellfish may be taken should be obtained from the Shellfish & Recreational Waters Branch, Watershed Assessment Section, Division of Water Resources, Department of Natural Resources and Environmental Control.
(k) Includes Primehook Creek watershed.
(l) Includes assorted minor watersheds not explicitly associated with any other designated stream basin.
(m) The specific portions of the Atlantic Ocean and the Delaware Bay for which the ERES designation shall apply shall be delineated in the Pollution Control Strategy developed for each of those waterbodies. The ERES designation for the Atlantic Ocean and the Delaware Bay does not include water explicitly associated with any other designated stream basis (e.g., Delaware Bay does not include St. Jones River).
(n) The Delaware Bay extends from River Mile 0.0 to 48.2 as shown on Figure 1.
(o) The Delaware River extends from River Mile 48.2 to 78.8 as shown in Figure 1.
(p) 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 have special criteria in Section 4.5 that are protective of open water fish and shellfish, shallow-water bay grass and migratory fish spawning and nursery designated uses consistent with the Maryland portion of the tidal Nanticoke River and as described in the U.S. Environmental Protection Agency document Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and its Tidal Tributaries (EPA 903-R-03-002). Attainment of the water quality criteria that apply to these waters will be determined following the guidelines documented within the same document and any future published addendums or modifications to that original publication.
(q) ERES designation is for Burrows Run from the Pennsylvania Line to the confluence with Red Clay Creek
x his designated water use to be protected throughout entire stream basin
- water uses not designated in the stream basin
* waters of exceptional recreational or ecological significance
** includes shellfish propagation
 

Figure 1 Delaware Watersheds and Waterbodies
Basin Boundaries to be used in determination of standards applicability are on file with the DNREC Division of Water Resources.
4.0 Criteria To Protect Designated Uses
4.1 All surface waters of the State (except as detailed in Sections 7 and 8) shall meet the following minimum criteria:
4.1.1 Waters shall be free from substances that are attributable to wastes of industrial, municipal, agricultural or other human-induced origin. Examples include but are not limited to the following:
4.1.1.1 Floating debris, oil, grease, scum, foam, or other materials on the water surface that may create a nuisance condition, or that may in any way interfere with attainment and maintenance of designated uses of the water,
4.1.1.2 Settleable solids, sediments, sludge deposits, or suspended particles that may coat or cover submerged surfaces and create a nuisance condition, or that may in any way interfere with attainment and maintenance of designated uses of the water,
4.1.1.3 Any pollutants, including those of a thermal, toxic, corrosive, bacteriological, radiological, or other nature, that may interfere with attainment and maintenance of designated uses of the water, may impart undesirable odors, tastes, or colors to the water or to aquatic life found therein, may endanger public health, or may result in dominance of nuisance species.
4.2 Narrative Criteria for Waters With the Public Water Supply Designated Use
4.2.1 Streams with a designated use of public water supply shall provide waters of acceptable quality for use for drinking, culinary or food processing purposes after application of approved treatment equivalent to coagulation, filtration, and disinfection (with additional treatment as necessary to remove naturally occurring impurities). The untreated waters are subject to the following limitations:
4.2.1.1 Waters shall be free from substances (except natural impurities) that, alone or in combination with other substances, result in:
4.2.1.1.1 Unacceptable levels of taste or odor in the treated water;
4.2.1.1.2 Significant disruption of the treatment processes at the treatment facility; or
4.2.1.1.3 Concentrations of toxic substances in the treated water that may be harmful to human health. The requirements of Section 4.5.10 4.6.3 shall apply.
4.3 Certain waters of the State are subject to natural variations in salinity such that those waters meet the definition of fresh at some times and marine at other times. For such waters, the more stringent of fresh or marine water quality criteria or standards as detailed throughout this document shall apply at all times unless otherwise specified by the Department.
4.4 Coordination with Delaware River Basin Commission:
For waters of the Delaware River and Delaware Bay, duly adopted Delaware River Basin Commission (DRBC) Water Quality Regulations shall be the applicable criteria. If the DRBC has not developed an applicable regulatory standard or criteria for these waters, and Delaware has, Delaware’s criteria shall be applicable.
4.5 The following criteria shall apply outside approved regulatory mixing zones unless otherwise specified:
4.5.1 Temperature, measured as Fahrenheit Degrees
4.5.1.1 Fresh Waters
4.5.1.1.1 Maximum increase above natural conditions shall be 5oF.
4.5.1.1.2 No human-induced increase of the true daily mean temperature above 82 oF shall be allowed.
4.5.1.1.3 No human-induced increase of the daily maximum temperature above 86oF shall be allowed.
4.5.1.2 Marine Waters
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:
4.5.1.2.2 No human-induced increase of the true daily mean temperature above 84 oF shall be allowed; and
4.5.1.2.3 No human-induced increase of the daily maximum temperature above 87oF shall be allowed.
4.5.1.3 Cold Water Fisheries (Put and Take)
4.5.1.3.1 Maximum increase above natural conditions shall be 5 oF.
4.5.1.3.2 No human-induced increase of the true daily mean temperature above 75 oF, shall be allowed
4.5.1.4 In all waters of the state, 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.
4.5.2 Dissolved Oxygen, measured as milligrams per liter (mg/L)
4.5.2.1 Fresh Waters
4.5.2.1.1 Daily average shall not be less than 5.5 mg/L.
4.5.2.1.2 Instantaneous minimum shall not be less than 4.0 mg/L
4.5.2.2 Marine Waters
4.5.2.2.1 Daily average shall not be less than 5.0 mg/L.
4.5.2.2.2 Instantaneous Minimum shall not be less than 4.0 mg/L
4.5.2.3 Cold Water Fisheries (Put and Take)
4.5.2.3.1 Daily average shall not be less than 6.5 mg/L during the applicable period.
4.5.2.3.2 Instantaneous Minimum shall not be less than 5.0 mg/L during the applicable period.
4.5.2.4 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
At water temperatures greater than 84 degrees Fahrenheit, instantaneous minimum shall not be less than 4.3 mg/L
4.5.2.4.1 For the period February 1- May 31:
4.5.2.4.1.1 7-Day mean shall not be less than 6.0 mg/L
4.5.2.4.1.2 Instantaneous minimum shall not be less than 5.0 mg/L
4.5.2.4.2 For June1- January 31
4.5.2.4.2.1 30 Day mean shall not be less than 5.5 mg/L
4.5.2.4.2.2 7-Day mean shall not be less than 4.0 mg/L
4.5.2.4.2.3 Instantaneous minimum shall not be less than 3.2 mg/L
4.5.2.5 All Waters
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.
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.
4.5.3 pH, measured in standard units, in all waters of the state
4.5.3.1 Shall be between 6.5 and 8.5 unless outside this range due solely to natural conditions. Where within this range, maximum human-induced change from background shall be 0.5 Standard Units; pH which results from human-induced change must remain within this range.
4.5.3.2 Where pH is below 6.5 or above 8.5 due solely to natural conditions, it shall not be lowered (where below 6.5) or raised (where above 8.5) more than 0.3 Standard Units due to human-induced changes.
4.5.4 Alkalinity, measured as mg/L as CaCO3, in all waters of the State shall not be less than 20 mg/L unless due solely to natural conditions. If less than 20 mg/L due solely to natural conditions, no reduction due to human-induced changes is allowed.
4.5.5 Turbidity Measured as Nephelometric or Formazin Turbidity Units, in all waters of the State shall not exceed natural levels by more than 10 units.
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
During the period of April 1 to October 31 the minimum seasonal averaged secchi depth shall be 1.0 m.
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.
4.5.7 Bacterial Water Quality Criteria
4.5.7.1 Primary and Secondary Contact Recreation Waters:
The following criteria shall apply:
(Enterococcus Colonies/100ml)
Geometric Mean (Enterococcus Colonies/100ml)
The purpose of these criteria is to provide the Department with a basis to assess water quality trends and pollution control needs with regard to primary and secondary contact recreation in waters of the State and to meet Federal BEACH Act Requirements. The criteria apply to enterococcus bacteria determined by the Department to be of non-wildlife origin based on best scientific judgment using available information. Swimming in waters affected by runoff during runoff periods may present an elevated risk of gastrointestinal illness and is not recommended.
4.5.7.2 Harvestable Shellfish waters:
The total coliform median MPN of the water shall not exceed 70/100 mL, nor shall more than 10% of the samples have an MPN in excess of 330/100 mL for a 3 decimal dilution test (or 230/100 mL where the 5 tube decimal test is used). These criteria shall be verified through sampling of those portions of the shellfish area most probably exposed to fecal contamination for those tidal and climatic conditions most likely to result in contamination of the shellfish area.
4.5.8 Nutrients
Nutrient overenrichment is recognized as a significant problem in some surface waters of the State.
4.5.8.1 It shall be the policy of this Department to minimize nutrient input to surface waters from point and human induced non-point sources.
4.5.8.2 The types of, and need for, nutrient controls shall be established on a site-specific basis. Nutrient controls may include, but shall not be limited to, discharge limitations or institution of best management practices.
4.5.8.3 For lakes and ponds, controls shall be designed to eliminate overenrichment.
4.5.8.4 For tidal portions of the stream basins of Indian River, Rehoboth Bay, and Little Assawoman Bay, controls needed to attain submerged aquatic vegetation growth season (approximately March 1 to October 31) average levels for dissolved inorganic nitrogen of 0.14 mg/L as N, for dissolved inorganic phosphorus of 0.01 mg/L as P, and for total suspended solids of 20 mg/L shall be instituted.
4.5.8.5 The specific measures to be employed by existing NPDES facilities to meet the aforementioned criteria shall be as specified in Section 5.6.3.4 of these standards.
4.5.9 Toxic Substances
4.5.9.1 Applicability: Criteria set forth in this section apply to all surface waters of the State, except as provided in Section 6, Regulatory Mixing Zones, Section 7, Critical Flows, and Section 8, Criteria for Low Flow Waters.
4.5.9.2 General Provisions:
4.5.9.2.1 Waters of the State shall not exhibit acute toxicity to fish, aquatic life, and wildlife, except in special cases applying to regulatory mixing zones as provided in Section 6.
4.5.9.2.2 Waters of the State shall not exhibit chronic toxicity to fish, aquatic life, and wildlife, except in regulatory mixing zones as provided in Section 6, at flows less than critical flows as provided in Section 7, or in low flow waters as provided in Section 8.
4.5.9.2.3 Waters of the State shall be maintained to prevent adverse toxic effects on human health resulting from ingestion of chemically contaminated aquatic organisms and drinking water.
4.5.9.2.4 The Department may consider synergistic, antagonistic, and additive impacts of combinations of toxicants to fish, aquatic life, and wildlife, and human health in assessing aggregate environmental impacts and mandating point and nonpoint source controls.
4.5.9.3 Specific Numerical Criteria:
4.5.9.3.1 Aquatic Life Criteria:
4.5.9.3.1.1 Aquatic Life Criteria for Aluminum, Iron, and Selenium in Table 1 are expressed on a total recoverable basis. Criteria for Cyanide in Table 1 are expressed as free cyanide at the lowest pH occurring in the receiving water, or cyanide amenable to chlorination. Criteria for all other metals in Table 1 are expressed on a total dissolved basis. For toxic substances where the relationship of toxicity is defined as a function of pH or hardness, numerical criteria are presented as an equation based on this relationship. Appropriate pH or hardness values for such criteria shall be determined on a case-by-case basis by the Department.
4.5.9.3.1.2 Specific numerical acute criteria as presented in Table 1 are applied as one-hour average concentrations not to be exceeded more than once in any three-year period. Specific numerical chronic criteria as presented Table 1 are applied as four-day average concentrations not to be exceeded more than once in any three-year period.
4.5.9.3.1.3 For toxic substances for which specific numerical criteria are not listed in Table 1, concentrations shall not exceed those which are chronically toxic (as determined from appropriate chronic toxicity data or calculated as 0.1 of LC50 values) to representative, sensitive aquatic organisms, except as provided in Section 6, Regulatory Mixing Zones, Section 7, Critical Flows, or Section 8, Criteria for Low Flow Waters. Concentrations so determined shall be applied as four-day average concentrations not to be exceeded more than once in any three-year period.
4.5.9.3.2 Human Health Criteria
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.
4.5.9.3.2.2 For compounds in Table 2 which are considered as both systemic toxicants and human carcinogens, criteria based on both human health concerns are presented. In determining pollution control requirements, the more stringent criterion, after consideration of critical (design) flows in Section 7, shall be utilized.
Marine Acute Criterion
Aluminum pH6.5-9.0
Temperature and pH dependent, see formula after this table
Temperature and pH dependent, see formula after this table
(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)
Chlorpyrifos (Dursban)
Chromium (III)*
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)
0.96*EXP(0.8545*LN(hardness)-1.702)
DDT and Metabolites (DDD and DDE)
Hexachloro-cylclohexane
(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)
.077 .77
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.
Formulas in the table have been formatted so that they can be copied directly into spreadsheets to calculate criteria. Criteria are calculated to two significant figures.
LN = natural log base e
EXP = e = 2.71828
Hardness is expressed as mg/L as CaCO3
pH is expressed as Standard Units
* Criteria is for total dissolved form
Where salmonid fish are present:
Criterion = -------------------- + -------------------
1 + 107.204-pH 1 + 10pH-7.204
Or where salmonid fish are not present:
Criterion = -------------------- + -------------------
1 + 107.204-pH 1 + 10pH-7.204
The thirty-day average concentration of total ammonia nitrogen (in mg N/L) does not exceed, more than once every three years on the average, the chronic criterion calculated using the following equations.
When fish early life stages are present:
Criterion = (---------- + ------------) * MIN (2.85, 1.45 *100.028*(25-T))
1 + 107.688-pH 1 + 10pH-7.688
When fish early life stages are absent:
Criterion= (----------------- + ---------------------) * [1.45 100.028*(25-MAX (T,7))]
_________ 1 + 107.688-pH 1 + 10pH-7.688
The highest four-day average within the 30-day period shall not exceed 2.5 times the chronic criterion.
Fish and Water Ingestion
Fish Ingestion
Fish and Water Ingestion
300 9.3
190 6.1
7 million fibers/L (MCL)
[28 3, 4]
[0.92 0.11]
75000 30000
2,4,5 Trichlorophenoxypropionic acid (2,4,5-TP- Silvex)
The columns labeled "Fish and Water Ingestion” shall apply only to waters of the State designated Public Water Supply sources in these standards.
The column labeled "Fish Ingestion Only" shall apply to all waters of the State not designated Public Water Supply sources in this document.
**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.
0.0001 0003
0.01 03
0. 0001 0003
0.0001 00003
0.0005 00003