| (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.
Cont'd... |
