Texas Administrative Code › Title 30 - ENVIRONMENTAL QUALITY › Part 1 - TEXAS COMMISSION ON ENVIRONMENTAL QUALITY › Chapter 307 - TEXAS SURFACE WATER QUALITY STANDARDS › Section 307.3 - Definitions and Abbreviations

Current through Reg. 49, No. 28; July 12, 2024
(a)
				Definitions. The following words and terms, when used in this chapter, have the
				defined meanings, unless the context clearly indicates otherwise.
(1) Acute toxicity--Toxicity that exerts a
				stimulus severe enough to rapidly induce an effect. The duration of exposure
				applicable to acute toxicity is typically 96 hours or less. Tests of total
				toxicity normally use lethality as the measure of acute impacts. (Direct
				thermal impacts are excluded from definitions of toxicity.)
(2) Ambient--Refers to the existing water
				quality in a particular water body.
(3) Aquatic vegetation--Refers to aquatic
				organisms, i.e., plant life, found in the water and includes phytoplankton;
				algae, both attached and floating; and vascular and nonvascular plants, both
				rooted and floating.
(4) Attainable
				use--A use that can be reasonably achieved by a water body in accordance with
				its physical, biological, and chemical characteristics whether it is currently
				meeting that use or not. Guidelines for the determination and review of
				attainable uses are provided in the standards implementation procedures. The
				designated use, existing use, or presumed use of a water body may not
				necessarily be the attainable use.
(5) Background--Refers to the water quality
				in a particular water body that would occur if that water body were relatively
				unaffected by human activities.
(6)
				Bedslope--Stream gradient, or the extent of the drop in elevation encountered
				as the stream flows downhill. One measure of bedslope is the elevation decline
				in meters over the stream distance in kilometers.
(7) Best management practices--Schedules of
				activities, maintenance procedures, and other management practices to prevent
				or reduce the pollution of water in the state from point and nonpoint sources,
				to the maximum extent practicable. Best management practices also include
				treatment requirements, operating procedures, and practices to control plant
				site runoff, spillage or leaks, sludge or waste disposal, or drainage from raw
				material storage.
(8)
				Bioaccumulative--Describes a chemical that is taken up by aquatic organisms
				from water directly or through the consumption of food containing the
				chemical.
(9) Bioaccumulation
				factor--A unitless value describing the degree to which a chemical can be
				concentrated in the tissues of an organism in the aquatic environment and that
				is absorbed through all routes of exposure, including the food chain. The
				bioaccumulation factor is the ratio of the concentration of a chemical in the
				tissue of an aquatic organism to the concentration of the chemical dissolved in
				ambient water at the site of sampling.
(10) Bioconcentration factor--A unitless
				value describing the degree to which a chemical can be concentrated in the
				tissues of an organism in the aquatic environment and that is absorbed directly
				from the water. The bioconcentration factor is the ratio of a chemical's
				concentration in the tissue of an organism compared to that chemical's average
				concentration in the surrounding water.
(11) Biological integrity--The species
				composition, diversity, and functional organization of a community of organisms
				in an environment relatively unaffected by pollution.
(12) Biotic ligand model--A metal
				bioavailability model that uses receiving water body characteristics to develop
				site-specific water quality criteria.
(13) Chronic toxicity--Toxicity that
				continues for a long-term period after exposure to toxic substances. Chronic
				exposure produces sub-lethal effects, such as growth impairment and reduced
				reproductive success, but it may also produce lethality. The duration of
				exposure applicable to the most common chronic toxicity test is seven days or
				more.
(14) Classified--Refers to a
				water body that is listed and described in Appendices A and C of §
										307.10 of this
				title (relating to Appendices A - G). Site-specific uses and criteria for
				classified water bodies are listed in Appendix A of §
										307.10 of this
				title.
(15) Coastal recreation
				waters--Marine coastal waters including oceans, coastal estuaries, and bays
				designated as primary contact recreation. Waters upstream of an unimpaired
				natural connection to the open sea or tidal inland waters are not considered
				coastal recreation waters (e.g., tidal rivers or streams).
(16) Commission--Texas Commission on
				Environmental Quality.
(17)
				Criteria--Water quality conditions that are to be met in order to support and
				protect desired uses, i.e., existing, designated, attainable, and presumed
				uses.
(18) Critical
				low-flow--Low-flow condition that consists of the seven-day, two-year low-flow
				or the alternative low-flows for spring-fed streams as discussed in §
										307.8(a)(2)
				of this title (relating to Application of Standards) and below which some
				standards do not apply.
(19)
				Designated use--A use that is assigned to specific water bodies in Appendix A,
				D, or G of §
										307.10 of this
				title (relating to Appendices A - G). Typical uses that may be designated for
				specific water bodies include domestic water supply, categories of aquatic life
				use, recreation categories, and aquifer protection.
(20) Discharge permit--A permit issued by the
				state or a federal agency to discharge treated effluent or cooling water into
				waters of the state.
(21) Dry
				weather flows--Sustained or typical dry, warm-weather flows between rainfall
				events, excluding unusual antecedent conditions of drought or wet
				weather.
(22) EC50
				--The concentration of a toxicant that produces an adverse effect
				on 50% of the organisms tested in a specified time period.
(23)
E. coli--Escherichia
				coli,
a subgroup of fecal coliform bacteria that is present in the
				intestinal tracts and feces of warm-blooded animals. It is used as an indicator
				of the potential presence of pathogens.
(24) Effluent--Wastewater discharged from any
				point source prior to entering a water body.
(25) Enterococci--A subgroup of fecal
				streptococci bacteria (mainly
Streptococcus faecalis
and
Streptococcus faecium
that is present in the intestinal tracts
				and feces of warm-blooded animals. It is used as an indicator of the potential
				presence of pathogens.
(26)
				Epilimnion--The upper mixed layer of a lake (including impoundments, ponds, and
				reservoirs).
(27) Existing use--A
				use that is currently being supported by a specific water body or that was
				attained on or after November 28, 1975.
(28) Fecal coliform--A portion of the
				coliform bacteria group that is present in the intestinal tracts and feces of
				warm-blooded animals; heat tolerant bacteria from other sources can sometimes
				be included. It is used as an indicator of the potential presence of
				pathogens.
(29) Freshwaters--Inland
				waters that exhibit no measurable elevation changes due to normal
				tides.
(30) Halocline--A vertical
				gradient in salinity under conditions of density stratification that is usually
				recognized as the point where salinity exhibits the greatest difference in the
				vertical direction.
(31) Harmonic
				mean flow--A measure of mean flow in a water course that is calculated by
				summing the reciprocals of the individual flow measurements, dividing this sum
				by the number of measurements, and then calculating the reciprocal of the
				resulting number.
(32) Incidental
				fishery--A level of fishery that applies to water bodies that are not
				considered to have a sustainable fishery but do have an aquatic life use of
				limited, intermediate, high, or exceptional.
(33) Industrial cooling impoundment--An
				impoundment that is owned or operated by, or in conjunction with, the water
				rights permittee, and that is designed and constructed for the primary purpose
				of reducing the temperature and removing heat from an industrial
				effluent.
(34) Industrial cooling
				water area--A designated area associated with a permitted wastewater discharge
				where numerical temperature criteria are not applicable in accordance with
				conditions and requirements specified in §
										307.4(f)
				of this title (relating to General Criteria) and §
										307.8(b)
				of this title (relating to Application of Standards).
(35) Intermittent stream--A stream that has a
				period of zero flow for at least one week during most years. Where flow records
				are available, a stream with a seven-day, two-year low-flow of less than 0.1
				cubic feet per second is considered intermittent.
(36) Intermittent stream with perennial
				pools--An intermittent stream that maintains persistent pools even when flow in
				the stream is less than 0.1 cubic feet per second.
(37) LC50 --The
				concentration of a toxicant that is lethal (fatal) to 50% of the organisms
				tested in a specified time period.
(38) Main pool station--A monitoring station
				that is located in the main body of a reservoir near the dam and not located in
				a cove or in the riverine portion or transition zone of a reservoir.
(39) Method detection limit--The minimum
				concentration of a substance that can be measured and reported with 99%
				confidence that the analyte concentration is distinguishable from the method
				blank results and is determined from analysis of a sample in a given matrix
				containing the analyte. The method detection limit is estimated in accordance
				with 40 Code of Federal Regulations Part 136, Appendix B.
(40) Minimum analytical level--The lowest
				concentration that a particular substance can be quantitatively measured with a
				defined accuracy and precision level using approved analytical methods. The
				minimum analytical level is not the published method detection limit for a
				United States Environmental Protection Agency-approved analytical method that
				is based on laboratory analysis of the substance in reagent (distilled) water.
				The minimum analytical level is based on analyses of the analyte in the matrix
				of concern (e.g., wastewater effluents). The commission establishes general
				minimum analytical levels that are applicable when information on
				matrix-specific minimum analytical levels is unavailable.
(41) Mixing zone--The area contiguous to a
				permitted discharge where mixing with receiving waters takes place and where
				specified criteria, as listed in §
										307.8(b)(1)
				of this title (relating to Application of Standards), can be exceeded. Acute
				toxicity to aquatic organisms is not allowed in a mixing zone, and chronic
				toxicity to aquatic organisms is not allowed beyond a mixing zone.
(42) Noncontact recreation--Activities that
				do not involve a significant risk of water ingestion, such as those with
				limited body contact incidental to shoreline activity, including birding,
				hiking, and biking. Noncontact recreation use may also be assigned where
				primary and secondary contact recreation activities should not occur because of
				unsafe conditions, such as ship and barge traffic.
(43) Nonpersistent--Describes a toxic
				substance that readily degrades in the aquatic environment, exhibits a
				half-life of less than 60 days, and does not have a tendency to accumulate in
				organisms.
(44) Nutrient
				criteria--Numeric and narrative criteria that are established to protect
				surface waters from excessive growth of aquatic vegetation. Nutrient numeric
				criteria for reservoirs are expressed in terms of chlorophyll
a
concentration per unit volume as a measure of phytoplankton
				density.
(45) Nutrient--A chemical
				constituent, most commonly a form of nitrogen or phosphorus, that in excess can
				contribute to the undesirable growth of aquatic vegetation and impact uses as
				defined in this title.
(46) Oyster
				waters--Waters producing edible species of clams, oysters, or
				mussels.
(47) Persistent--Describes
				a toxic substance that is not readily degraded and exhibits a half-life of 60
				days or more in an aquatic environment.
(48) Pollution--The alteration of the
				physical, thermal, chemical, or biological quality of, or the contamination of,
				any water in the state that renders the water harmful, detrimental, or
				injurious to humans, animal life, vegetation, or property or to the public
				health, safety, or welfare, or impairs the usefulness or the public enjoyment
				of the water for any lawful or reasonable purpose.
(49) Point source--Any discernible, confined
				and discrete conveyance, including but not limited to any pipe, ditch, channel,
				tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated
				animal feeding operation, or vessel or other floating craft, from which
				pollutants or wastes are or may be discharged into or adjacent to any water in
				the state.
(50) Presumed use--A use
				that is assigned to generic categories of water bodies (such as perennial
				streams). Presumed uses are superseded by designated uses for individual water
				bodies in Appendix A, D, or G of §
										307.10 of this
				title (relating to Appendices A - G).
(51) Primary contact recreation 1--Activities
				that are presumed to involve a significant risk of ingestion of water (e.g.,
				wading by children, swimming, water skiing, diving, tubing, surfing,
				handfishing as defined by Texas Parks and Wildlife Code, §
										66.115, and the
				following whitewater activities: kayaking, canoeing, and rafting).
(52) Primary contact recreation 2--Water
				recreation activities, such as wading by children, swimming, water skiing,
				diving, tubing, surfing, handfishing as defined by Texas Parks and Wildlife
				Code, §
										66.115, and
				whitewater kayaking, canoeing, and rafting, that involve a significant risk of
				ingestion of water but that occur less frequently than for primary contact
				recreation 1 due to:
(A) physical
				characteristics of the water body; or
(B) limited public access.
(53) Protection zone--Any area
				within the watershed of a sole-source surface drinking water supply that is:
(A) within two miles of the normal pool
				elevation of a body of surface water that is a sole-source surface drinking
				water supply;
(B) within two miles
				of that part of a perennial stream that is:
(i) a tributary of a sole-source surface
				drinking water supply; and
(ii)
				within three linear miles upstream of the normal pool elevation of a
				sole-source surface drinking water supply; or
(C) within two miles of that part of a stream
				that is a sole-source surface drinking water supply, extending three linear
				miles upstream from the water supply intake (Texas Water Code, §
											26.0286)
				.
(54) Public drinking
				water supply--A water body designated to provide water to a public water system
				as defined in Chapter 290 of this title (relating to Public Drinking
				Water).
(55) Saltwater--A coastal
				water that has a measurable elevation change due to normal tides. In the
				absence of tidal information, saltwater is generally considered to be a coastal
				water that typically has a salinity of two parts per thousand or greater in a
				significant portion of the water column.
(56) Salinity--The total dissolved solids in
				water after all carbonates have been converted to oxides, all bromide and
				iodide have been replaced by chloride, and all organic matter has been
				oxidized. For most purposes, salinity is considered equivalent to total
				dissolved salt content. Salinity is usually expressed in parts per
				thousand.
(57) Seagrass
				propagation--A water-quality-related existing use that applies to saltwater
				with significant stands of submerged seagrass.
(58) Secondary contact recreation
				1--Activities that commonly occur but have limited body contact incidental to
				shoreline activity (e.g. fishing, canoeing, kayaking, rafting, and motor
				boating). These activities are presumed to pose a less significant risk of
				water ingestion than primary contact recreation 1 or 2 but more than secondary
				contact recreation 2.
(59)
				Secondary contact recreation 2--Activities with limited body contact incidental
				to shoreline activity (e.g. fishing, canoeing, kayaking, rafting, and motor
				boating) that are presumed to pose a less significant risk of water ingestion
				than secondary contact recreation 1. These activities occur less frequently
				than secondary contact recreation 1 due to physical characteristics of the
				water body or limited public access.
(60) Segment--A water body or portion of a
				water body that is individually defined and classified in Appendices A and C of
				§
										307.10 of this
				title (relating to Appendices A - G) in the Texas Surface Water Quality
				Standards. A segment is intended to have relatively homogeneous chemical,
				physical, and hydrological characteristics. A segment provides a basic unit for
				assigning site-specific standards and for applying water quality management
				programs of the agency. Classified segments may include streams, rivers, bays,
				estuaries, wetlands, lakes, or reservoirs.
(61) Settleable solids--The volume or weight
				of material that settles out of a water sample in a specified period of
				time.
(62) Seven-day, two-year
				low-flow (7Q2)--The lowest average stream flow for seven consecutive days with
				a recurrence interval of two years, as statistically determined from historical
				data. As specified in §
										307.8 of
				this title, some water quality standards do not apply at stream flows that are
				less than the 7Q2 flow.
(63)
				Shellfish--Clams, oysters, mussels, crabs, crayfish, lobsters, and
				shrimp.
(64) Sole-source surface
				drinking water supply--A body of surface water that is identified as a public
				water supply in rules adopted by the commission under Texas Water Code, §
										26.023
				and is the sole source of supply of a public water supply system, exclusive of
				emergency water connections (Texas Water Code, §
										26.0286)
				.
(65) Standard Methods for the
				Examination of Water and Wastewater--A document describing sampling and
				analytical procedures that is published by the American Public Health
				Association, American Water Works Association, and Water Environment
				Federation. The most recent edition of this document is to be followed whenever
				its use is specified by this chapter.
(66) Standards--Desirable uses (i.e.,
				existing, attainable, designated, or presumed uses as defined in this section)
				and the narrative and numerical criteria deemed necessary to protect those uses
				in surface waters.
(67) Standards
				implementation procedures--Methods and protocols in the guidance document
Procedures to Implement the Texas Surface Water Quality
				Standards
(RG-194), as amended and approved by the commission and
				EPA.
(68) Stormwater--Rainfall
				runoff, snow melt runoff, surface runoff, and drainage.
(69) Stormwater discharge--A point source
				discharge that is composed entirely of stormwater associated with an industrial
				activity, a construction activity, a discharge from a municipal separate storm
				sewer system, or other discharge designated by the agency.
(70) Stream order--A classification of stream
				size, where the smallest, unbranched tributaries of a drainage basin are
				designated first order streams. Where two first order streams join, a second
				order stream is formed; where two second order streams join, a third order
				stream is formed, etc. For purposes of water quality standards application,
				stream order is determined from United States Geological Survey topographic
				maps with a scale of 1:24,000.
(71)
				Surface water in the state--Lakes, bays, ponds, impounding reservoirs, springs,
				rivers, streams, creeks, estuaries, wetlands, marshes, inlets, canals, the Gulf
				of Mexico inside the territorial limits of the state as defined in the Texas
				Water Code, §
										26.001, and all other
				bodies of surface water, natural or artificial, inland or coastal, fresh or
				salt, navigable or nonnavigable, and including the beds and banks of all
				water-courses and bodies of surface water, that are wholly or partially inside
				or bordering the state or subject to the jurisdiction of the state; except that
				waters in treatment systems that are authorized by state or federal law,
				regulation, or permit, and that are created for the purpose of waste treatment
				are not considered to be water in the state.
(72) Sustainable Fisheries--Descriptive of
				water bodies that potentially have sufficient fish production or fishing
				activity to create significant long-term human consumption of fish. Sustainable
				fisheries include perennial streams and rivers with a stream order of three or
				greater; lakes and reservoirs greater than or equal to 150 acre-feet or 50
				surface acres; all bays, estuaries, and tidal rivers. Water bodies that are
				presumed to have sustainable fisheries include all designated segments listed
				in Appendix A of §
										307.10 of this
				title (relating to Appendices A - G) unless specifically exempted.
(73) Thalweg--The deepest portion of a stream
				or river channel cross-section.
(74) Tidal--Descriptive of coastal waters
				that are subject to the ebb and flow of tides. For purposes of standards
				applicability, tidal waters are considered to be saltwater. Classified tidal
				waters include all bays and estuaries with a segment number that begins with
				24xx, all streams with the word tidal in the segment name, and the Gulf of
				Mexico.
(75) To discharge--Includes
				to deposit, conduct, drain, emit, throw, run, allow to seep, or otherwise
				release or dispose of, or to allow, permit, or suffer any of these acts or
				omissions.
(76) Total dissolved
				solids--The amount of material (inorganic salts and small amounts of organic
				material) dissolved in water and commonly expressed as a concentration in terms
				of milligrams per liter. The term is equivalent to the term filterable residue,
				as used in 40 Code of Federal Regulations Part 136 and in previous editions of
				the publication entitled,
Standard Methods for the Examination of Water
				and Wastewater.
(77) Total
				maximum daily load (TMDL)--The total amount of a substance that a water body
				can assimilate and still meet the Texas Surface Water Quality
				Standards.
(78) Total suspended
				solids--Total suspended matter in water, which is commonly expressed as a
				concentration in terms of milligrams per liter. The term is equivalent to
				nonfilterable residue, as used in 40 Code of Federal Regulations Part 136 and
				in previous editions of the publication entitled,
Standard Methods for
				the Examination of Water and Wastewater.
(79) Total toxicity--Toxicity as determined
				by exposing aquatic organisms to samples or dilutions of instream water or
				treated effluent. Also referred to as whole effluent toxicity or
				biomonitoring.
(80) Toxic
				equivalency factor--A factor to describe an order-of-magnitude consensus
				estimate of the toxicity of a compound relative to the toxicity of
				2,3,7,8-tetraclorodibenzo-p-dioxin (2,3,7,8-TCDD). The factor is applied to
				transform various concentrations of dioxins and furans or dioxin-like
				polychlorinated biphenyls into equivalent concentrations of 2,3,7,8-TCDD,
				expressed as a toxic equivalency.
(81) Toxic equivalency--The sum of the
				products from the concentration of each dioxin and furan, or dioxin-like
				polychlorinated biphenyl congener, multiplied by its respective toxic
				equivalency factor to give a single 2,3,7,8-tetraclorodibenzo-p-dioxin
				equivalent.
(82) Toxicity--The
				occurrence of adverse effects to living organisms due to exposure to toxic
				materials. Adverse effects caused by conditions of temperature and dissolved
				oxygen are excluded from the definition of toxicity. With respect to the
				provisions of §
										307.6(e)
				of this title (relating to Toxic Materials), which concerns total toxicity and
				biomonitoring requirements, adverse effects caused by concentrations of
				dissolved salts (such as sodium, potassium, calcium, chloride, carbonate) in
				source waters are excluded from the definition of toxicity. Source water is
				defined as surface water or groundwater that is used as a public water supply
				or industrial water supply (including a cooling-water supply). Source water
				does not include brine water that is produced during the extraction of oil and
				gas, or other sources of brine water that are substantially uncharacteristic of
				surface waters in the area of discharge. In addition, adverse effects caused by
				concentrations of dissolved salts that are added to source water by industrial
				processes are not excluded from the requirements of §
										307.6(e)
				of this title, except as specifically noted in §
										307.6(e)(2)(B)
				of this title, which concerns requirements for toxicity testing of 100%
				effluent. This definition of toxicity does not affect the standards for
				dissolved salts in this chapter other than §
										307.6(e)
				of this title. The standards implementation procedures contain provisions to
				protect surface waters from adverse effects of dissolved salts and methods to
				address the effects of dissolved salts on total toxicity tests.
(83) Toxicity biomonitoring--The process or
				act of determining total toxicity. Documents that describe procedures for
				toxicity biomonitoring are cited in §
										307.6
				of this title (relating to Toxic Materials). Also referred to simply as
				biomonitoring.
(84) Water-effect
				ratio (WER)--The WER is calculated as the toxic concentration
				(LC50) of a substance in water at a particular site,
				divided by the toxic concentration of that substance as reported in laboratory
				dilution water. The WER can be used to establish site-specific acute and
				chronic criteria to protect aquatic life. The site-specific criterion is equal
				to the WER times the statewide aquatic life criterion in §
										307.6(c)
				of this title.
(85) Water quality
				management program--The agency's overall program for attaining and maintaining
				water quality consistent with state standards, as authorized under the Texas
				Water Code, the Texas Administrative Code, and the federal Clean Water Act,
				§§106, 205(j), 208, 303(e) and 314 (33 United States
				Code, §§
											1251
et
				seq.).
(86) Wetland--An
				area (including a swamp, marsh, bog, prairie pothole, or similar area) having a
				predominance of hydric soils that are inundated or saturated by surface or
				groundwater at a frequency and duration sufficient to support and that under
				normal circumstances supports the growth and regeneration of hydrophytic
				vegetation. The term "hydric soil" means soil that, in its undrained condition,
				is saturated, flooded, or ponded long enough during a growing season to develop
				an anaerobic condition that supports the growth and regeneration of hydrophytic
				vegetation. The term "hydrophytic vegetation" means a plant growing in: water
				or a substrate that is at least periodically deficient in oxygen during a
				growing season as a result of excessive water content. The term "wetland" does
				not include irrigated acreage used as farmland; a man-made wetland of less than
				one acre; or a man-made wetland where construction or creation commenced on or
				after August 28, 1989, and that was not constructed with wetland creation as a
				stated objective, including but not limited to an impoundment made for the
				purpose of soil and water conservation that has been approved or requested by
				soil and water conservation districts. If this definition of wetland conflicts
				with the federal definition in any manner, the federal definition
				prevails.
(87) Wetland water
				quality functions--Attributes of wetlands that protect and maintain the quality
				of water in the state, which include stormwater storage and retention and the
				moderation of extreme water level fluctuations; shoreline protection against
				erosion through the dissipation of wave energy and water velocity, and
				anchoring of sediments; habitat for aquatic life; and removal, transformation,
				and retention of nutrients and toxic substances.
(88) Zone of initial dilution--The small area
				at the immediate point of a permitted discharge where initial dilution with
				receiving waters occurs and that may not meet certain criteria applicable to
				the receiving water. A zone of initial dilution is substantially smaller than a
				mixing zone.