Report No. 14
Idaho Water Quality Policy for Nonpoint Source Pollution: A Manual for Decision-Makers
Executive Summary
(Part 9)

GLOSSARY

NOTE: In almost all cases, definitions are taken verbatim from the source document indicated in parentheses following the definition. Terms appearing in boldface within the definitions are elsewhere defined in this Glossary. Some terms have more than one definition or slightly different meanings depending on the source.

Activity: see agriculture, forest practices, nonpoint source activities, short-term activity.

Agriculture: A category of nonpoint source pollution including but not limited to activities of irrigated or non-irrigated crop production, specialty crop production (truck farming, orchards, etc.), pasture land, rangeland, feedlots, aquaculture, and animal holding areas (IDEQ 1995b).

Ambient: The quality of physical parameters in the surrounding, external, or unconfined conditions (e.g., water temperature or water pollution); the term has no positive or negative connotations (Dunster and Dunster 1996).

Antidegradation: [1] Part of the federal air quality and water quality requirements prohibiting deterioration where pollution levels are above legal limits (IDEQ 1995b). See degradation.
[2] For purposes of the Clean Water Act, section 303, refers to pollution prevention by (1) maintaining and protecting the level of water quality necessary to protect existing uses, (2) allowing lowered water quality where doing so would accommodate important economic or social development in the area in which the waters are located, but assuring that water quality is adequate to protect existing uses fully, and (3) maintaining and protecting high quality waters where they are an outstanding National resource (40 CFR 131.12). See outstanding resource water.

Applicable water quality standard: Those water quality standards identified in the rules of the Department (Idaho Code § 39-3602).

Aquatic: Of, or pertaining to, water (IDEQ 1996).

Attainable use: [1] A beneficial use, that with appropriate point source and nonpoint source controls, a water body could support in the future (IDEQ 1996).
[2] Those uses, based on the state's system of water-use classifications, that can be achieved when effluent limitations under sections 301(b)(1)(A) and (B) and 306 of the CWA are implemented for point source discharges and when "cost-effective and reasonable best management practices" (40 CFR 131.12(a)(2)) are implemented for nonpoint sources (Novotny and Olem 1994, p. 986).

Background: [1] The ever-present environmental conditions or effects above which a phenomenon must manifest itself in order to be detected. The background level may serve as a baseline against which changes can be judged (Dunster and Dunster 1996).
[2] The biological, chemical, or physical conditions of waters measured at a point immediately upstream (up gradient) of the influence of an individual discharge from a point source or nonpoint source. If several discharges to the water exist or if an adequate upstream point of measurement is absent, the Department will determine where background conditions should be measured (IDEQ 1996).

Bad actor law: State bad actor laws authorize the state to take increasingly stringent steps where voluntary measures fail (EPA 1996b).

Baseline: The starting point for analysis, which may be the conditions at a point in time (e.g., when inventory data are collected) or it may be the average of a set of data collected over a specified period of time (Dunster and Dunster 1996).

Basin: An area having no, or very limited, outlets for surface waters, for example, a lake basin or a river basin (Dunster and Dunster 1996); for the purposes of the Idaho Code, there are six major river basins, listed in Table 7 and depicted on the cover of this report. See Basin Advisory Group.

Basin Advisory Group (BAG): A citizen advisory group named by the Idaho Division of Environmental Quality Director in consultation with the designated agencies, for the State's major river basins that shall generally advise the Director on water quality objectives for each basin and work in a cooperative manner with the Director to achieve these objectives (IDEQ 1996).

Bed load: Stream-transported materials, such as sediments and small rocks, transported along the stream bed in the lower levels of streamflow by dragging or rolling (Dunster and Dunster 1996).

Beneficial use: [1] The reasonable use of water for a purpose consistent with the laws and interests of the people of the State (Dunster and Dunster 1996).
[2] Any of the various uses that may be made of water, including, but limited to, aquatic biota, recreation in or on the water, water supply, wildlife habitat, and aesthetics (IDEQ 1996).
[3] Protected uses of water as described in the Water Quality Standards and Waste Water Treatment Requirements (IDAPA 16.01.2003) (IDL 1995).

Beneficial Use Reconnaissance Project (BURP): A process employed by the Idaho Division of Environmental Quality (DEQ) to characterize stream health or conditions through measurement of biological, chemical, and physical habitat parameters (IDL 1995). See reconnaissance.

Best management practice (BMP): [1] Methods, measures, or practices designed to reduce or prevent water pollution, usually applied as a system of practices rather than a single practice (Dunster and Dunster 1996).
[2] Practices, techniques or measures developed, or identified, by the designated agency and identified in the state water quality management plan which are determined to be the cost-effective, practicable means of preventing or reducing pollutants generated from nonpoint sources to a level compatible with water quality goals (Idaho Code § 39-3602).
[3] Procedures or controls other than effluent limitations to prevent or reduce pollution of surface water (includes runoff control, spill prevention, and operating procedures) (IDEQ 1995b).

Biota, biotic: The plants and animals of a specified area (IDEQ 1996).

BLM: Bureau of Land Management, United States Department of the Interior.

Board: The Idaho Board of Health and Welfare (Idaho Code § 39-3602).

Body of water: See water body.

CFR: Code of Federal Regulations.

Channel: A discernible waterway that continuously or periodically contains moving water within a defined bed or banks (Dunster and Dunster 1996).

Characteristic: A physical, chemical, or biological parameter or other measurable variable used to describe water quality.

Clean sediment: Sediment that is not contaminated by chemical substances. Pollution caused by clean sediment refers to the quantity of sediment, as opposed to the presence of pollutant-contaminated sediment (EPA 1996b).

Clean Water Act (CWA): The 1977 amendments to the Federal Water Pollution Control Act of 1972; the CWA is widely used to refer to the 1972 Act and all subsequent amendments to it, including the Water Quality Act amendments of 1987.

Contaminant: Any physical, chemical, biological, or radiological substance or matter that has an adverse effect on air, water, or soil (IDEQ 1995b). See pollutant.

Cost-effectiveness: The usefulness of specific inputs (costs) to produce specific outputs (benefits). In measuring cost-effectiveness, some outputs, including environmental, economic, or social impacts, are assigned in physical terms (Dunster and Dunster 1996).

Criteria: [1] Elements of water quality standards, expressed as constituent concentrations, levels, or narrative statements, representing a quality of water that supports a particular use. When criteria are met, water quality will generally protect the designated use (EPA 1995a; 40 CFR 131.3).
[2] Either a narrative or numerical statement of water quality on which to base judgement of suitability for a beneficial use (IDEQ 1996).
[3] Criteria, unlike standards, are resource quality levels that have been determined by the accumulation of scientific data showing the relationship between levels of quality and damage to the resource (Dunster and Dunster 1996).

Cumulative effects: The resulting outcomes of many different effects acting together (Dunster and Dunster 1996).

Cumulative watershed effects (CWE): The impact on water quality and/or beneficial uses which result from the incremental impact of two or more forest practices; CWE can result from individually minor but collectively significant actions taking place over a period of time (IDL 1995).

Degradation: [1] The deterioration of air, land or water quality through natural or human-induced changes (IDEQ 1995b).
[2] In the context of the EPA's antidegradation policy requirements, the regulations (40 CFR 131.12) have been criticized for failing to define "degradation" (Burk et al. 1995). In an Interim Draft of Advanced Notice of Proposed Rulemaking dated February 27, 1996, the EPA asked for public comments: "Should EPA add definitions of important terms to the regulation, including a definition of 'degradation' which recognizes that temporary or short-term effects on waters need not be subject to antidegradation provisions? Should definition of 'short-term' and 'significant' also be included?" (EPA 1996c).

Department: The Idaho Department of Health and Welfare (Idaho Code § 39-3602).

Designated agency: The Idaho Department of Lands for timber harvest activities, for oil and gas exploration and development and for mining activities; the Idaho Soil Conservation Commission for grazing activities and for agricultural activities; the Idaho Department of Transportation for public road construction; the Idaho Department of Agriculture for aquaculture; and the Idaho Department of Health and Welfare's Division of Environmental Quality for all other activities (Idaho Code § 39-3602).

Designated use or designated beneficial use: [1] A use specified in water quality standards for each water body or segment whether or not the use is being attained (EPA 1995a; 40 CFR 131.3).
[2] Those uses assigned to waters as identified in the rules of the Department whether or not the uses are being attained; designated uses may include subcategories of existing uses that the Director determines are not fully attainable (Idaho Code § 39-3602).
[3] A beneficial use assigned to identified waters in the Idaho Department of Health and Welfare Rules, Title 1, Chapter 2, Water Quality Standards and Wastewater Treatment Requirements (IDEQ 1996).

Director: The Director of the Idaho Department of Health and Welfare, or his or her designee (Idaho Code § 39-3602); or the Director of the Department of Health and Welfare's Division of Environmental Quality (IDEQ 1996).

Discharge: [1] Any spilling, leaking, emitting, escaping, leaching, or disposing of a pollutant into the waters of the State; a discharge shall not include surface water runoff from nonpoint sources or natural soil disturbing events (Idaho Code § 39-3602).
[2] The release of any waste into the environment from a point source; usually refers to the release of a liquid waste into a water body through an outlet such as a pipe (IDEQ 1995b).
[3] The amount of water flowing in the stream channel at the time of measurement; usually expressed as cubic feet per second (cfs) (IDEQ 1996).

Drainage: The surface or sub-surface water derived within a clearly defined catchment area, usually bounded by ridges or other similar topographic features, encompassing part, most, or all of a watershed (Dunster and Dunster 1996).

Ecological indicator: An analysis, based on metrics, that measures a water body's environmental integrity (e.g. index of biotic integrity) as compared to a reference condition (IDEQ 1996).

Ecological integrity: Attainable when physical, chemical, and biological integrity occur simultaneously (Dissmeyer 1994).

Ecosystem: The interacting system of a biological community and its nonliving environmental surroundings (IDEQ 1995b).

Ecosystem management: A management practice and philosophy aimed at selecting, maintaining, and/or enhancing the ecological integrity of an ecosystem in order to ensure a continued healthy ecosystem while providing resources, products, or non-consumptive values for humans (Dunster and Dunster 1996).

Effluent: Wastewater discharged from a point source such as a pipe (IDEQ 1995b).

Effluent limitation: Any restriction established by the State on quantities, rates, and concentrations of chemical, physical, biological and other constituents which are discharged from point sources into navigable waters (CWA § 502).

Environment, environmental: The sum of all external conditions affecting the life, development, and survival of an organism (IDEQ 1995b).

EPA: The United States Environmental Protection Agency.

Erosion: [1] The wearing away of the land surface by running water, wind, ice, or other geological agents; [2] detachment and movement of soil or rock fragments by water, wind, ice, or gravity (Dunster and Dunster 1996).

Existing beneficial use or existing use: [1] 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 (40 CFR 131.3).
[2] A beneficial use present in waters on or after November 28, 1975, whether or not the use is designated for those waters in the Water Quality Standards and Wastewater Treatment Requirements (IDEQ 1996).
[3] Those surface water uses actually attained on or after November 28, 1975, whether or not they are designated uses. Existing uses that are not fully attainable may form the basis for subcategories of designated uses (Idaho Code § 39-3602).

Federal Advisory Committee Act (FACA): Provides for the establishment of an advisory committee by the President or a federal agency to obtain advice or recommendations (EPA 1996b).

Forest practices or forestry: Activities in silviculture.

Full support: An Idaho category of water quality status. A water body whose status is "full support" is in compliance with those levels of water quality criteria listed in Idaho's Water Quality Standards and Wastewater Treatment Requirements, or with reference conditions approved by the Idaho Division of Environmental Quality Director in consultation with the appropriate Basin Advisory Group (IDEQ 1996, adapted from Idaho Code § 39-3602). Contrast with not full support.

Fully supporting: A federal category of water quality status. Water quality condition is good, meaning it meets criteria for designated uses (EPA 1995b).

Grazing: Is considered an agricultural activity for the purposes of the Clean Water Act.

Ground water: The water beneath the surface of the earth (IDEQ 1995b).

Guidelines: A set of recommended or suggested methods or actions that should be followed in most circumstances to assist administrative and planning decisions, and their implementation in the field; a broad framework of recommended actions to be taken and, therefore, provide some flexibility for decision-making (Dunster and Dunster 1996). Contrast with standards.

Habitat: Those parts of the environment on which an organism depends, directly or indirectly, in order to carry out its life processes (Dunster and Dunster 1996).

Healthy ecosystem: An ecosystem in which the structure and functions permit the maintenance of the desired condition of biological diversity, biotic integrity, and ecological processes over time (Dunster and Dunster 1996).

High quality waters: An undefined term used in the EPA's antidegradation policy (Burk et al. 1995). See outstanding resource water.

Hydrologic/habitat modification (term used in Table 3): Hydrologic modifications alter the flow of water; examples include channelization, dewatering, damming, and dredging. Habitat modifications include activities in the landscape, on shore, and in water bodies that alter the physical structure of aquatic ecosystems and have adverse impacts on aquatic life; examples include removal of streamside vegetation, excavation of cobbles, stream burial, and excessive suburban sprawl (EPA 1995b).

Impact: When an activity has caused pollutants to enter surface waters (IDEQ 1989). Contrast with impair.

Impair, impairment of beneficial uses, impaired waters: [1] Water bodies that do not provide full support for beneficial uses, including designated uses and existing uses (EPA 1995c).
[2] The sum of water bodies partially supporting uses and not supporting uses (EPA 1995b, 1996c). See also Water quality-limited water. The EPA is revisiting the definition (EPA 1996b).

Integrity: An unimpaired condition; the quality or state of being complete (IDEQ 1996). Such an assessment requires knowledge of what an unimpaired baseline looks like so that integrity can be judged in a defensible context (Dunster and Dunster 1996).

Lower water quality: A measurable adverse change in a chemical, physical, or biological parameter of water relevant to a designated beneficial use, and which can be expressed numerically. Measurable adverse change is determined by a statistically significant difference between sample means using standard methods for analysis and statistical interpretation appropriate to the parameter. Statistical significance is defined as the ninety-five percent (95%) confidence limit when significance is not otherwise defined for the parameter in standard methods or practices (Idaho Code § 39-3602).

Mining: See resource extraction.

Monitoring: The process of checking, observing, and measuring outcomes for key variables against stated objectives or standards (Dunster and Dunster 1996).

National Pollutant Discharge Elimination System (NPDES): The point source permitting program established pursuant to section 402 of the federal Clean Water Act (Idaho Code § 39-3602). In Idaho, the EPA administers this program.

Natural: A condition without human-based disruptions (IDEQ 1996); the EPA recognizes that the term "natural" is undefined (EPA 1995c).

Navigable waters: Refers to waters of the United States (33 USC 1362).

Needs verification: An Idaho category of water quality status. A water body whose status is "needs verification" has not been assessed, due to need for additional information that will allow distinction between "full support" and "not full support." (IDEQ 1996)

New nonpoint source activity: A new nonpoint source activity or a substantially modified existing nonpoint source activity on or adversely affecting an outstanding resource water which includes, but is not limited to, new silviculture activities, new mining activities and substantial modifications to an existing mining permit or approved plan, new recreational activities and substantial modifications to existing recreational activities, new residential or commercial development that includes soil disturbing activities, new grazing activities and substantial modifications to existing grazing activities, except that reissuance of existing grazing permits, or grazing activities and practices authorized under an existing permit, is not considered a new activity. It does not include naturally occurring events such as floods, landslides, and wildfire including prescribed natural fire (Idaho Code § 39-3602).

Nonpoint source: Pollution that is not released through pipes but rather originates from multiple sources over a relatively large area. Nonpoint source can be divided into nonpoint source activities related to either land or water use including failing septic tanks, improper animal-keeping practices, forest practices, and urban and rural runoff (EPA 1996b). Contrast with point source.

Nonpoint source activities: Includes grazing, crop production, silviculture, log storage or rafting, construction, mining, recreation, septic systems, runoff from storms and other weather-related events and other activities not subject to regulation under a federal NPDES permit. Nonpoint source activities on waters designated as outstanding resource waters do not include issuance of water rights permits or licenses, allocation of water rights, operation of diversions, or impoundments (Idaho Code § 39-3602). See new nonpoint source activities.

Nonpoint source pollution: [1] polluted surface runoff (Tarlock 1996); [2] Pollution that is discharged over a wide land area, not from one specific location (IDEQ 1996); [3] any source of pollution not associated with a distinct discharge point, including sources such as rainwater, runoff from agricultural lands, industrial sites, parking lots, and silvicultural operations, as well as escaping gases from pipes and fittings (IDEQ 1995b). See nonpoint source activities.

Nonpoint source runoff: Water which may carry pollutants from nonpoint source activities into the waters of the State (Idaho Code § 39-3602).

Not assessed: An Idaho category of water quality status. A water body whose status is "not assessed" has not been assessed, due to data limitation (IDEQ 1996).

Not attainable: A federal category of water quality status. Water quality is poor, and the state has performed a use attainability analysis and demonstrated that use support is not attainable due to one of the six conditions specified in 40 CFR 131.10(g) (EPA 1995b).

Not full support: An Idaho category of water quality status. A water body whose status is "not full support" is not in compliance with those levels of water quality criteria listed in Idaho's Water Quality Standards and Wastewater Treatment Requirements, or with reference conditions approved by the Director in consultation with the appropriate Basin Advisory Group (IDEQ 1996). Contrast with full support.

Not supporting: A federal category of water quality status. Water quality condition is poor (impaired), meaning water quality frequently fails to meet criteria for designated use (EPA 1995b).

Outstanding resource water: A high quality water, such as water of national and state parks and wildlife refuges and water of exceptional recreational or ecological significance, which has been so designated by the Idaho Legislature. It constitutes an outstanding national or state resource that requires protection from point source and nonpoint source activities that may lower water quality (Idaho Code § 39-3602).

Parameter: Any attribute, variable, or physical property in a set of variables or properties that, taken together, characterize or determine a system's behavior (Dunster and Dunster 1996). See characteristic.

Partially supporting: A federal category of water quality status. Water quality condition is fair (impaired), meaning it fails to meet criteria for designated use at times (EPA 1995b).

Person: Any individual, association, partnership, firm, joint stock company, joint venture, trust, estate, political subdivision, public or private corporation, state or federal governmental department, agency or instrumentality, or any legal entity, which is recognized by law as the subject of rights and duties (Idaho Code § 39-3602).

Point source: [1] Pollution that is discharged from any identifiable point, including pipes, ditches, channels, sewers, tunnels, and containers of various types (IDEQ 1996).
[2] 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 are, or may be, discharged. This term does not include return flows from irrigated agriculture (CWA § 502; Idaho Code § 39-3602), discharges from dams and hydroelectric generating facilities or any source or activity considered a nonpoint source by definition (Idaho Code § 39-3602).

Pollutant: [1] Any substance introduced into the environment that adversely affects the usefulness of a resource (IDEQ 1995b).
[2] Materials which, when discharged or released to water in excessive quantities cause or contribute to water pollution. Examples include dredged spoil, solid waste, incinerator residue, sewage, garbage, sewage sludge, munitions, chemical waste, biological materials, radioactive materials, heat, wrecked or discarded, equipment, rock, sand, silt, cellar dirt; and industrial, municipal and agricultural waste, gases entrained in water, or other materials. Provided however, biological materials shall not include live or occasional dead fish that may accidentally escape into the waters of the State from aquaculture facilities (Idaho Code § 39-3602).

Pollution: [1] The man-made or man-induced alteration of the chemical, physical, biological, and radiological integrity of water (CWA § 502).
[2] Any alteration in the character or quality of the environment that renders it unfit or less suited for beneficial uses (IDEQ 1996). See water pollution.

Receiving waters: Waters into which a contaminant or a pollutant is introduced.

Reconnaissance: An exploratory or preliminary survey of an area (IDEQ 1996).

Reference stream or reference condition: [1] Describes the characteristics of water body segments least impaired by human activities. As such, reference conditions can be used to describe attainable biological or habitat conditions for water body segments with common watershed/catchment characteristics within defined geographical regions (EPA 1995a).
[2] A condition that fully supports applicable beneficial uses, with little effect from human activity and representing the highest level of support attainable (IDEQ 1996).
[3] A stream or other water body which represent the following: (a) the minimum conditions necessary to fully support the designated beneficial uses; (b) natural conditions with few impacts from human activities and which are representative of the highest level of support attainable in the basin. In highly mineralized areas or in the absence of such reference streams or water bodies, the Director, in consultation with the Basin Advisory Group and the technical advisers to it, may define appropriate hypothetical reference conditions or may use monitoring data specific to the site in question to determine conditions in which the beneficial uses are fully supported (Idaho Code § 39-3602).

Resource extraction (term used in Table 3): Mining, petroleum drilling, and runoff from mine tailing sites (EPA 1995b).

Riparian: Pertaining to anything connected with or immediately adjacent to the banks of a stream or other body of water (Dunster and Dunster 1996).

Riparian zone: The area adjacent to the stream that is covered by the type of vegetation that indicates the presence of water at or near the surface. It includes wetlands and those portions of floodplains and valley bottoms that support riparian vegetation. These areas may be narrow (<5 feet) or wide (>100 feet) (IDL 1995).

Runoff: The part of precipitation and snowmelt that reaches streams by flowing over or through the ground; surface runoff flows away without penetrating the soils (Dunster and Dunster 1996). See nonpoint source runoff.

Sediment: [1] Soil particles that enter the water from erosion of land. Sediment consists of particles of all sizes, including fine clay particles, silt, sand, and gravel (EPA 1995b).
[2] Fragmented material that originates from the weathering of rocks and decomposition of organic material that is transported in suspension by water, air, or ice, to be subsequently deposited at a new location (Dunster and Dunster 1996).

Sewage: The waste and wastewater produced by residential and commercial establishments and discharged into sewers (IDEQ 1995b).

Short-term or temporary activity: An activity which is limited in scope and is expected to have only minimal impact on water quality as determined by the Director. Short-term or temporary activities include, but are not limited to, maintenance of existing structures, limited road and trail reconstruction, soil stabilization measures, and habitat enhancement structures (Idaho Code § 39-3602).

Silt, siltation: The suspension and deposition of small sediment particles in water bodies (EPA 1995b).

Silviculture: Activities associated with the regeneration, growing and harvesting of trees and timber including, but not limited to, disposal of logging slash, preparing sites for new stands of trees to be either planted or allowed to regenerate through natural means, road construction and road maintenance, drainage of surface water which inhibits tree growth or logging operations, fertilization, application of herbicides or pesticides, all logging operations, and all forest management techniques employed to enhance the growth of stands of trees or timber (Idaho Code § 39-3602). See forest practices.

Soil Conservation Commission means an agency of State government as created in section 22-2718, Idaho Code (Idaho Code § 39-3602).

Soil Conservation District means an entity of State government as defined in section 22-2717, Idaho Code (Idaho Code § 39-3602).

Standards: Quantifiable and measurable thresholds that are typically defined in law or regulation, and are mandatory. Standards are typically established using a combination of best available scientific knowledge, tempered by cautious use of an established safety or caution factor (Dunster and Dunster 1996). See guidelines and water quality standards.

State: The state of Idaho (Idaho Code § 39-3602).

State Revolving Fund (SRF): Revolving funds are financial institutions that make loans for specific water pollution control purposes and use loan repayment, including interest, to make new loans for additional water pollution control activities. Under the State Revolving Fund program, States and municipalities are primarily responsible for financing, constructing, and managing wastewater treatment facilities. The SRF program is based on the 1987 amendments to the Clean Water Act, which called for replacement of the Construction Grants program with the SRF program (EPA 1996b).

State water quality management plan: Idaho's management plan developed and updated by the Department of Health and Welfare in accordance with the federal Clean Water Act (Idaho Code § 39-3602).

Stream segment: An identified section of stream segregated by channel characteristics and adjacent landtype associations (IDL 1995).

Stream segment of concern (SSOC): Stream segments about which the public has expressed significant concern (IDEQ 1995b).

Suspended sediment: Sediment suspended in a fluid by the upward components of turbulent currents (Dunster and Dunster 1996).

Threatened: A federal category of water quality status. Water quality condition is good, meaning it supports beneficial uses now but may not in the future unless action is taken (EPA 1995b). The EPA is revisiting the definition (EPA 1996b).

Threatened waters: Water quality supports beneficial uses now but may not in the future unless action is taken CWA (§ 305(b)). Draft TMDL guidance specifies that "Where all water quality problems cannot be addressed immediately, EPA and the States will...set priorities and direct efforts and resources to maximize environmental benefits by dealing with the most serious water quality problems and the most valuable and threatened resources first" (EPA 1996b).

Total maximum daily load (TMDL): [1] the total amounts of a particular pollutant that sources can discharge without violating water quality standards.
[2] The sum of the individual wasteload allocations for point sources, load allocations for nonpoint sources, and natural background levels of all pollutants. Acceptable pollutant levels, established through TMDLs shall be at a level necessary to implement the applicable water quality standards for the identified pollutants with seasonal variations (Idaho Code § 39-3602).
[3] The sum of the individual wasteload allocations (WLAs) for point sources, load allocations (LAs) for nonpoint sources and natural background, and a margin of safety (MOS). TMDLs can be expressed in terms of mass per time, toxicity, or other appropriate measure that relates to a state's water quality standards (EPA 1996b).
[4] A TMDL allocates pollution control responsibilities among pollution sources in a watershed, and is the basis for taking actions needed to restore a water body (EPA 1996b).

Total maximum daily load (TMDL) protocols: TMDL protocols are under development and will provide a process and selected procedures for developing TMDLs for impaired waters. They will include the following six elements: (1) problem statement, (2) endpoints, (3) source assessment, (4) endpoint and source linkage, (5) allocation, and (6) monitoring (EPA 1996b).

Unimpaired: See fully supporting.

Use attainability analysis (UAA): A structured scientific assessment of the use which may include physical, chemical, biological, and economic factors (EPA 1995a; 40 CFR 131.3).
[2] Assesses the physical, chemical, biological and economic factors which affect the attainment of a designated use. If a UAA shows that attaining a designated use is not feasible, a state can modify it to make the use less stringent (EPA 1996b).

Waste water: The spent or used water from individual homes, a community, a farm, or an industry that contains dissolved or suspended matter (IDEQ 1995b).

Water body: [1] A homogeneous classification that can be assigned to rivers, lakes, estuaries, coastlines, or other water features (IDEQ 1996).
[2] The EPA recognizes 5 types of bodies of water for the purposes of the Clean Water Act: streams, lakes, estuaries, coastal waters, and wetlands (Novotny and Olem 1994).
[3] For the purposes of the Idaho Code, see waters.

Water pollution: [1] The man-made or human-induced alteration of the chemical, physical, biological, and radiological integrity of water (EPA 1995a; 33 USC 1362).
[2] Such alteration of the thermal, chemical, biological or radioactive properties of any waters of the State, or such discharge or release of any contaminant into the waters of the state as will or is likely to create a nuisance or render such waters harmful or detrimental or injurious to public health, safety or welfare or to domestic, commercial, industrial, recreational, aesthetic or other legitimate uses or to livestock, wild animals, birds, fish or other aquatic life (Idaho Code § 39-3602).

Water quality: [1] The chemical, physical, and biological characteristics of water (Dunster and Dunster 1996).
[2] A term used to describe the biological, chemical, and physical characteristics of water with respect to its suitability for a beneficial use (IDEQ 1996).

Water quality-limited water: [1] Refers to any [water body] segment where it is known that water quality does not meet applicable water quality standards and/or is not expected to meet applicable water quality standards even after application of technology-based effluent limitations required by the Clean Water Act (EPA 1995a; 40 CFR 131.3), and other pollution control requirements (e.g., best management practices) required by local, state, or federal authority (40 CFR 130.7(b)).
[2] Similar in meaning to impaired, waters that require TMDLs when certain pollution control requirements "are not stringent enough" to implement water quality standards (EPA 1996b; 40 CFR 130.7(b)). See also impaired waters.

Water quality standards: [1] State-adopted and EPA-approved ambient standards for water bodies. The standards cover the use of the water body and the water quality criteria that must be met to protect the designated use or uses (EPA 1996b).
[2] Provisions of state or federal law which consist of a designated use or uses for the waters of the United States and water quality criteria for such waters based upon such uses (EPA 1995a, 40 CFR 131.3). Minimum standards include an antidegradation policy consistent with 40 CFR 131.12 (40 CFR 131.6).
[3] The combination of a designated use and the maximum concentration of a pollutant which will protect the use for any given water body (IDEQ 1995b).

Water quality status: [1] In the federal scheme there are five categories, based on levels of support of criteria for designated use of the water body. The categories are fully supporting, threatened, partially supporting, not supporting, and not attainable (EPA 1995b).
[2] In Idaho's scheme there are four categories based on levels of support of criteria for designated use and available information: full support, not full support, needs verification, and not assessed (IDEQ 1996).

Waters: All the accumulations of surface water, natural and artificial, public and private, or parts thereof which are wholly or partially within, flow through or border upon this State. For the purposes of the Idaho Code, water bodies shall not include municipal or industrial wastewater treatment or storage structures or private reservoirs, the operation of which has no effect on waters of the state (Idaho Code § 39-3602).

Waters of the United States: All lakes, rivers, streams, wetlands, impoundments, and tributaries that may be susceptible to use in interstate or foreign commerce; and territorial seas; except wastewater treatment system ponds or lagoons (adapted from 40 CFR 232.2).

Watershed: [1] The land area from which water flows into a stream or other body of water which drains the area. For the purposes of the Idaho Code, the area of watersheds shall be recommended by the Basin Advisory Group (Idaho Code § 39-3602).
[2] The topographic boundary, usually a height of land, that marks the dividing line from which surface streams flow in two different directions (Dunster and Dunster 1996). See drainage.

Watershed Advisory Group (WAG): A citizen advisory group named by the Idaho Division of Environmental Quality Director in consultation with the appropriate Basin Advisory Group which shall generally be responsible for recommending those specific actions needed to control point source and nonpoint source pollution within the watershed so that, within reasonable periods of time, designated beneficial uses are fully supported (Idaho Code §§ 39-3615, 16).

Watershed analysis: A systematic procedure for characterizing watershed and ecological processes to meet specific management and social objectives; a stratum of ecosystem management planning applied to watersheds of approximately 20 to 200 square miles (Dunster and Dunster 1996).

Wetlands: Those areas that are soaked or flooded by surface or ground water frequently enough or for sufficient duration to support plants, birds, animals, and aquatic life. Wetlands generally include swamps, marshes, bogs, estuaries, and other inland and coastal areas (IDEQ 1995b).