Glossary

24-Hour Dissolved Oxygen (DO) Measurements - The measurement of dissolved oxygen over a 24-hour period using deployed, unattended, automated equipment preset to record and store field measurements over one 24-hour period. These measurements are used to assess Aquatic Life Use.

Algae - Aquatic plants that lack true roots, stems and leaves. For the physical assessment described in this document, algae consist of nonvascular plants that attach to rocks and debris or float freely in the water. Such plants may be green, blue-green, or olive-green, and are slimy to the touch. They usually have a coarse filamentous structure.

Ambient - The existing water quality in a particular water body.

Ammonia-Nitrogen (NH₃-N) - Ammonia, naturally occurring in surface and wastewaters, is produced by the breakdown of compounds containing organic nitrogen.

Aquatic Life Use (ALU) - Refers to a use designation for a water body and how well it can support abundant and diverse aquatic life

Assessment Unit (AU) - The smallest geographic area of a water body that can support a designated or site-specific use.

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.

Basin - A large geographic drainage area comprised of watersheds. See River Basin and Coastal Basin.

Benthos/Benthics - see Macrobenthic Invertebrate

Best Management Practices (BMP) - Schedules of activities, maintenance procedures, and other practices to prevent or reduce the pollution of water to the maximum extent practicable.

Bloom - The accelerated growth of algae and/or higher aquatic plants in a body of water. Bloom is often related to pollutants that increase the rate of growth.

Channelization - Straightening and deepening streams so water will move faster.

Chloride (Cl^-) - One of the major inorganic ions in water and wastewater. Concentrations can be increased by industrial processes. High chloride concentrations can affect metallic objects and plants.

Chlorophyll-a - A photosynthetic pigment found in all green plants. The concentration of chlorophyll-a is used to estimate the phytoplankton in an area of surface water.

Classified - Refers to a water body that is listed and described in Appendix A or Appendix C of the Texas Surface Water Quality Standards.

Coastal Basin - A collection of watersheds adjacent to the coastline that water flows through on its way to the ocean.

Contact Recreation - Recreational activities involving a significant risk of ingestion of water; including wading by children, swimming, water skiing, diving, and surfing. See also noncontact recreation.

Conventional Parameters - A list of basic parameters that require laboratory analyses. The parameters frequently include, but are not limited to, solids (TSS, TDS, VSS), nutrients (nitrogen and phosphorus compounds), chlorides, sulfates, hardness, and TOC.

Criteria - Water-quality conditions that are to be met in order to support and protect desired uses.

Data Sonde - A water-quality monitoring device that calculates and records field parameters.

Designated Use - A use that is assigned to specific water bodies in Appendix A or in Appendix D of the Texas Surface Water Quality Standards. Typical uses designated for specific water bodies include domestic water supply, categories of Aquatic Life Use, kinds of recreation, and aquifer protection.

Dioxin - A family of polychlorinated chemicals found in waste from the paper bleaching processes and the combustion of chlorinated compounds. Dioxin is considered carcinogenic and can disrupt the reproductive and immune systems in humans.

Dissolved Oxygen (DO) - The oxygen freely available in water. Dissolved oxygen is vital to fish and other aquatic life and for the prevention of odors. Traditionally, the level of dissolved oxygen has been accepted as the single most important indicator of a water body’s ability to support desirable aquatic life.

Effluent - Wastewater (treated or untreated) that flows out of a treatment plant or industrial outfall (point source) prior to entering a water body.

Enterococci - A subgroup of fecal streptococcal bacteria (mainly Streptococcus faecalis and Streptococcus faecium) found in the intestinal tracts and feces of warm-blooded animals. It is used as an indicator of the potential presence of pathogens.

Escherichia coli (E. coli) - E. coli is a member of the total coliform group of bacteria found in feces. It is an indicator of fecal contamination and possible presence of enteric pathogens (viral, protozoan, and bacterial pathogens of the gastrointestinal route).

Estuary - Regions of interaction between rivers and near shore ocean waters, where tidal action and river flow create a mixing of fresh and salt water.

Fecal Coliform - A subset of the coliform bacteria group that is found 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.

Field Parameters - A list of basic tests generally collected in the field using equipment and meters. The list also includes visual observations.

General Use - Refers to the overall quality of water. Several water quality constituents are evaluated to ensure and safeguard the general use of a water body.

Habitat - The area in which an organism lives.

Impoundment - A body of water confined by a dam, dike, floodgate, or other barrier.

Indicator Organism - An organism, species or community that indicates the presence of a certain environmental condition or conditions.

Loess Plot - A graph that shows the relationship of two variables (measurements or parameter values) made using a technique that calculates the slope of the plotted line at different time periods (locally weighted least-squares regression), producing a line that usually shows inflections (change points) rather than a straight line that best fits all points. LOESS is not really an acronym, and can be thought of as “LOcal regrESSion.”

Macrobenthic Invertebrate - Aquatic bottom-dwelling fauna. Common types are flat worms, leeches, snails, and various insect species.

Nekton - Free-swimming organisms (for example, fish, insects).

Nitrate-Nitrogen (NO₃-N) - A compound containing nitrogen that can exist as a dissolved solid in water. Excessive amounts can have harmful effects on humans and animals (>10 mg/L).

Nitrite-Nitrogen (NO₂-N) - An intermediate oxidation state in the nitrification process (ammonia, nitrite, and nitrate).

Noncontact Recreation (NCR) - Aquatic recreational pursuits not involving a significant risk of water ingestion and limited body contact incidental to shoreline activity, such as fishing, and commercial and recreational boating. See also contact recreation.

Nonpoint Source (NPS) - A pollution source that is diffuse and does not have a single point of origin or is not introduced into a receiving stream from a specific outfall. The pollutants are generally carried off the land by stormwater runoff. The commonly used categories for nonpoint sources are agriculture, forestry, urban, mining, construction, dams and channels, land disposal, and saltwater intrusion.

Nutrient - Any substance used by living things to promote growth. The term is generally applied to nitrogen and phosphorus in water and wastewater, but is also applied to other essential and trace elements.

Outfall - A designated point of effluent (treated liquid waste) discharge.

Oyster Waters - Waters producing edible species of clams, oysters, or mussels.

Parameter - Refers to a water quality constituent used to evaluate water quality.

pH - The hydrogen-ion activity of water caused by the breakdown of water molecules and presence of dissolved acids and bases.

Phosphorus - A nutrient essential to the growth of organisms. It can be the nutrient limiting the primary productivity of water. In excessive amounts from wastewater, agricultural drainage, and certain industrial waste it can contribute to the eutrophication (the natural aging progression) of lakes and other water bodies.

Pollution - The alteration of the physical, thermal, chemical, or biological quality of, or the contamination of, any water that renders it harmful, detrimental, or injurious to humans, animal life, vegetation, property, or the public health, safety, or welfare. Pollution may impair the usefulness or the public enjoyment of the water for any lawful or reasonable purpose.

Polychlorinated Biphenyls (PCBs) - A class of organic compounds used in dielectric fluids in transformers, capacitors, and coolants. PCBs are highly toxic and are associated with endocrine disruption and neural toxicity in humans.

Public Drinking Water Supply - A water body designated to provide water to a public water system.

Recreational Use - Refers to how safely a water body can support activities that involve the possibility of ingesting or encountering water.

Recreational Use Attainment Analysis (RUAA) - An analysis determining the appropriate contact recreation use designation for a water body.

Reservoir - Any natural or artificial holding area used to store, regulate, or control water.

River Basin - The land area drained by a river and its tributaries.

Routine Monitoring - Monitoring activities that occur at least quarterly, and at a minimum, include collecting field measurements, conventional chemical parameters, bacterial measurements, and flow measurements.

Runoff - Precipitation or irrigation water that runs off land into water bodies.

Screening Criteria Levels - Concentration amounts derived from statistical distributions of statewide water quality monitoring data. The 85th percentile for each applicable parameter is used as the screening criteria level.

Sediment - Particles of sand, clay, silt, and plant or animal matter carried in water and deposited in reservoirs and slow-moving areas of streams and rivers.

Segment - A water body or portion of a water body that is individually defined and classified 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. Classified segments may include streams, rivers, bays, estuaries, wetlands, lakes, and reservoirs.

Specific Conductance - A measure of the carrying capacity for electrical current, in mhos/cm, of 1 cm³ of water at 25°C. Dissolved substances in water dissociate into ions with the ability to conduct electrical current. Conductivity is a measure of how salty the water is. Salty water has high conductivity.

Stormwater - Rainfall runoff, snow-melt runoff, surface runoff, and drainage.

Subwatershed - Small drainage areas of a stream, creek, or portion of a larger water body.

Sulfate (SO₄^2-) - An ion derived from rocks and soils containing gypsum, iron sulfides, and other sulfur compounds. Sulfates are widely distributed in nature.

Texas Surface Water Quality Standards (TSWQS) - Establishes explicit goals for the quality of water bodies and designates water bodies for appropriate uses, including the narrative and numerical criteria deemed necessary to protect those uses.

Tidal - Describes coastal waters subject to the ebb and flow of tides. For purposes of standards applicability, tidal waters are saltwater. Classified tidal waters include all bays and estuaries with a segment number that begins with 24--, all streams with the word tidal in the segment name, and the Gulf of Mexico.

Total Dissolved Solids (TDS) - The sum of nitrogen in ammonia (NH₃-N), ammonium (NH₄⁺-N), and organically-bound nitrogen.

Total Kjeldahl Nitrogen (TKN) - The sum of nitrogen in ammonia (NH₃-N), ammonium (NH₄⁺-N), and organically-bound nitrogen.

Total Maximum Daily Load (TMDL) - The total amount of a substance a water body can assimilate and still meet the Texas Surface Water Quality Standards.

Total Suspended Solids (TSS) - The amount of organic and inorganic suspended particles in water.

Tributary - A stream or river that flows into a larger one.

Unclassified Segment - Often tributaries of classified segments and do not have specific water quality standards assigned in the TSWQS. These segments are assessed based on the criteria of the classified segment into which they flow. However, there are exceptions to this rule. Some unclassified segments have been assigned specific water quality standards in the TSWQS. Unclassified segments are assigned the same four-digit code as the classified segment and a letter that is specific to that waterway.

Use Attainment Analysis (UAA) - This analysis determines if the natural characteristics of a water body cannot attain the currently designated uses and/or criteria

Water body - Refers to any mass of water. A water body can be contained, like a lake or a bay, or in motion, such as a river, creek, or bayou.

Water Quality - Used to describe the chemical, physical, and biological characteristics of water to ensure suitability for general or designated uses.

Water Quality Monitoring - The process of sampling and analyzing water quality parameters over time.

Watershed - The area of land from which precipitation drains to a single point. Watersheds are sometimes referred to as drainage basins or drainage area

Watershed Protection Plan (WPP) - A community-based, stakeholder-driven framework that uses a holistic/watershed approach to address potential sources of impaired waterways. The plan is developed with community involvement, and the measures to reduce pollutants are voluntary.