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Our Company - Glossary | Alabama Power
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Acre (ac)
A measure of land area measuring 43,560 square ft.
Acre-Foot (af)
The amount of water it takes to cover one acre to a depth of one foot, 43,560 cubic feet or 1,233.5 cubic meters
Active Solar
The use of mechanical devices such as collectors, storage tanks, and pumps to capture heat energy from the sun for use in space heating/cooling and water heating systems. Other applications include the generation of electricity from solar energy.
Active Storage
The volume of water in a reservoir between its minimum operating elevation and its maximum normal operating elevation.
Actual Demand
The maximum rate at which energy is used, as measured in kilowatts (kW) in 15 or 30 minute intervals.
An almost vertical pipe or short horizontal passage entering a tunnel, either to add water from a conduit, sluice or other water source or as a maintenance access tunnel (also referred to as a portal if located at the beginning or end of the tunnel).
A reservoir located immediately downstream from a powerhouse, sometimes used to re-regulate flows to the river or stream.
Material such as sand, silt or clay, deposited on land by water such as on floodplains.
A unit of measurement of electric current, akin to cubic feet of water flowing per second.
Anadromous Fish
Fish that live in saltwater habitats most of their lives, but periodically migrate into freshwater to spawn and develop to the juvenile stage (e.g., alewife).
Annual Fuel Utilization Efficiency (AFUE)
The total heating output of a furnace during its normal annual usage period for heating, divided by the total energy used.
Area of Potential Effect as pertaining to Section 106 of the National Historic Preservation Act.
Aquatic Life
Any plants or animals which live at least part of their life cycle in water.
Automatic/Semi-automatic/Manual Powerhouses
An automatic powerhouse can be started, stopped, and have its load and voltage changed from a remote or master station, via supervisory control. A semiautomatic powerhouse with SCADA may allow a remote station to change load and/or voltage, and may allow a remote shutdown, but must be started manually. A semi-automatic powerhouse without SCADA will send alarms to a remote or master station. A manual powerhouse must have all its functions performed at the powerhouse.


Pressed mats of glass fiber, mineral wool or other insulating material sold in 4' and 8' lengths.
A set of existing environmental conditions upon which comparisons are made during the NEPA process.
Base Load
A power plant that is planned to run continually except for maintenance and scheduled or unscheduled outages. Also refers to the nearly steady level of demand on a utility system.
Associated with lake or river bottom or substrate.
Benthic Macroinvertebrates
Animals without backbones, which are visible to the eye and which live on, under, and around rocks and sediment on the bottoms of lakes, rivers, and streams.
Black Star Capability
The ability of a unit to start up without the use of an external transmission or distribution voltage power source.
Pressed mats of glass fiber, mineral wool or other insulating material sold in continuous rolls that may be cut to any lengths.
British Thermal Unit (BTU)
A measure of heat equal to the amount of heat necessary to raise the temperature of one pound of water one degree F.
Bypass Reach
The original water channel of the river that is directly affected by the diversion of water though the penstocks to the generating facilities. This portion of the river, the "bypassed reach" may remain watered or become dewatered.


Degrees Celsius.
Coefficient of Performance. Ratio of the rate of heat delivered versus the rate of energy output in consistent units. Or a complete, operating heat pump system operating under design conditions.
The load for which an electric generating unit, or other electrical equipment or power line is rated.
Catadromous Fish
Fish that live in freshwater most of their lives and when mature migrate to the sea to spawn (e.g., American eel).
A compound that may have a base of oil, resin, latex or other materials, applied wherever two different materials or parts of the building, such as windows and door frames, meet.
Certificate of Convenience and Necessity
A term used by public service commissions in granting authority to a company to render utility service, usually specifying the area and other conditions of service.
Clean Water Act (CWA)
The Federal Water Pollution Control Act of 1972 and subsequent amendments in 1977, 1981, and 1987 (commonly referred to as the Clean Water Act). The Act established a regulatory system for navigable waters in the United States, whether on public or private land. The Act set national policy to eliminate discharge of water pollutants into navigable waters, to regulate discharge of toxic pollutants, and to prohibit discharge of pollutants from point source without permits. Most importantly it authorized EPA to set water quality criteria for states to use to establish water quality standards.
Joint production of electricity and useful heat/steam from a common source.
Soil material and/or rock fragments moved by gravity such as during creep, slide, or localized wash-outs, which is deposited at the base of steep slopes.
Combustion Turbine
A fuel-fired turbine engine used to drive an electric generator.
Federal Energy Regulatory Commission also referenced as FERC.
Any material (such as a power line) that allows its electrons to be easily transferred.
A tunnel or pipe, used for diverting or moving water from one point to another, usually used when there is no existing streambed or waterway.
A process or program designed to increase the efficiency of energy and water use, production, or distribution.
Cooling Ton
Measure of cooling capacity equal to 12,000 BTU/hr.
Creel Census
Counting and interviewing anglers to determine fishing effort and catch. Usually conducted by a census clerk on systematic regularly scheduled visits to significant fishing areas.
Critical Energy Infrastructure Information (CEII)
Project-related documents that are restricted from public viewing in accordance with FERC regulations (18 CFR 388.113) related to the design and safety of dams and appurtenant facilities, and that is necessary to protect national security and public safety.
Cubic Feet (cf)
The volume of a cube with edges one foot in length.
Cubic Feet Per Second (cfs)
A measurement of water flow representing one cubic foot of water moving past a given point in one second. One cfs is equal to 0.0283 cubic meters per second and 0.646 mgd.
Cultural Resources
Includes items, structures, etc. of historical, archaeological, or architectural significance.
Cumulative Impact
The effect on the environment that results from the incremental impact of the action when added to other past, present, and reasonably foreseen future actions. Can result from individually minor but collectively significant actions taking place over a period of time.


A structure constructed across a water body typically used to increase the hydraulic head at hydroelectric generating units. A dam typically reduces the velocity of water in a particular river segment and increases the depth of water by forming an impoundment behind the dam. It also generally serves as a water control structure.
Degree Day
A unit that represents one degree of decline from a given point (such as 65oF) in the mean outdoor temperature of one day. Often used in estimating fuel requirements of buildings.
The rate at which electric energy is delivered to or by a system at a given instant or averaged over a designated period, usually expressed in kilowatts or megawatts.
Demand Charge
A separate charge based upon the demand for electric service by a commercial or industrial customer, based on the investment in facilities necessary to serve them.
Dependable Capacity
The maximum dependable MW output of a generator or group of generators during the critical hydrologic period coincident with peak electrical system load.
One of several hydroelectric plants collectively licensed by the Federal Energy Regulatory Commission as a Project (e.g., The Coosa River Project consists of five developments: Weiss, Henry, Logan Martin, Lay, and Bouldin).
A raised bank, typically earthen, constructed along a waterway to impound the water and to prevent flooding.
Dissolved Oxygen (DO)
A commonly employed measure of water quality that describes the amount of oxygen dissolved in water. Low DO levels adversely affect aquatic life.
Distribution Lines
Power lines, like those in neighborhoods, used to carry moderate voltage electricity which is "stepped down" to household levels by transformers on power poles.
Distribution System
The substations, transformers and lines that convey electricity from high-voltage transmission lines to the consumer.
The distance the water surface of a reservoir is lowered from a given elevation as the result of releasing water.
A pipe or tube through which heated or cooled air flows.


Energy Efficiency Ratio. Ratio used to rate the efficiency of air conditioners.
The motion of electrons through a conductor.
Electronic Funds Transfer (EFT)
Bill payment through automatic transfer from your bank account to the utility payment account.
Electrostatic precipitators
Pollution control devices attached to fossil fuel generating plants which prevent the vast majority of fly ash from being released into the air.
Emergent aquatic vegetation
Plants rooted in substrate covered by shallow water (of up to 6.6 ft depth), with most of the parts out of the water.
Eminent Domain
The authority to acquire land from a private owner for the benefit of public use.
Average power production over a stated interval of time, expressed in kilowatt-hours, megawatt-hours, average kilowatts and average megawatts.
Energy Lifestyle
The energy-usage habits of individuals and how they can be improved to use energy wisely and reduce monthly consumption.
Environmental Impact Statement (EIS)
An environmental review document prepared under NEPA to determine the environmental impact of a specific action. A Draft Environmental Impact Statement (DEIS) is prepared and circulated for public comment. After incorporation of public comments, a Final Environmental Impact Statement (FEIS) is published.
Waters with a high concentration of nutrients and a high level of primary production.
The evaporation from all water, soil, snow, ice, vegetation, and other surfaces, plus transpiration.


Degrees Fahrenheit.
Federal Energy Regulatory Commission (FERC)
The governing federal agency responsible for overseeing the licensing/relicensing and operation of hydroelectric projects in the United States.
Federal Power Act (FPA)
Federal statute enacted in 1920 that established the Federal Power Commission (now FERC) and the statutes for licensing hydroelectric projects.
Federal Power Commission (FPC)
Predecessor of FERC.
Federal Register
A publication of the Federal Government that includes official transactions of the U.S. Congress, as well as all federal agencies such as FERC. Copies of the Federal Register are usually available at large public and university libraries.
The volume of water passing a given point per unit time.
Flow Duration Curve
A graphical representation of the percentage of time in the historical record that a flow of any given magnitude has been equaled or exceeded.
Fly Ash
Small particles of airborne ash produced by burning fossil fuels.
A measure of how much light is reaching a given location. Using foot-candles to measure light is akin to using a thermometer to measure temperature.
A reservoir upstream from a powerhouse, from which water is drawn into a tunnel or penstock for delivery to the powerhouse.
Franchise Fee
A local tax imposed on utilities for the privilege of providing a service within city limits.
Francis turbine
A radial-inflow reaction turbine, where flow through the runner is perpendicular to the turbine shaft.
Any substance that can be used to produce heat or some other form of energy.
Fuel Adjustment Charge (FAC)
Fuel adjustment or fuel recovery charges are based on the current month's cost of fuel to operate the power generation plants. FACs or FRCs vary from 1¢ - 5¢ per kWh. Because tariff rate schedules are set for the year, if fuel costs have decreased since the rate was set, the charge can appear as a credit on the bill. (also called fuel cost recovery)
Fuel adjustment clause
an annual adjustment in rates based on changes in the price of fuel used to generate electricity.
Fuel Cost Recovery (FCR)
Fuel adjustment or fuel recovery charges are based on the current month's cost of fuel to operate the power generation plants. FACs or FRCs vary from 1¢ - 5¢ per kWh. Because tariff rate schedules are set for the year, if fuel costs have decreased since the rate was set, the charge can appear as a credit on the bill.


The process of producing electricity from other forms of energy, such as steam, heat, or water. Refers to the amount of electric energy produced, expressed in kilowatt hours.
A machine that converts mechanical energy into electricity often powered by a turbine.
Grizzly Trash Rack
A metal grating across the entry to a water conduit.
Gross Storage
The sum of the dead storage and the live storage volumes of a reservoir, the total amount of water contained in a reservoir at its maximum normal operating elevation.


H-Frame Structure
A wood pole transmission structure that consists of two wood poles with a horizontal cross arm above the conductor.
The locality or external environment in which a plant or animal normally lives and grows.
The distance that water falls in passing through a hydraulic structure or device such as a hydroelectric plant. Gross head is the difference between the headwater and tailwater levels; net head is the gross head minus hydraulic losses such as friction incurred as water passes through the structure; and rated head is the head at which the full-gate discharge of a turbine will produce the rated capacity of the connected generator.
The waters immediately upstream of a dam. For power dams, also referred to as the water in the impoundment which supplies the turbines (see also forebay).
Heat Exchanger
A mechanical device used to transfer heat from one medium to another, such as from water to air.
Heat Gain
The amount of heat flowing into a home as a result of sunshine, warm air leakage, warming of the walls and roof, and heat given off by people and equipment.
Heat Loss
The amount of heat in a building that is lost as a result of heat flow through walls, windows, and roof, and air leakage through many parts of the thermal envelope.
Heat Pump
A year-round space-conditioning system capable of both heating and cooling. A heat pump always delivers more BTUs than are in the electrical energy used to operate it.
Heat Pump Water Heater
Single unit that both heats water and provides spot cooling.
Heat Recovery Unit
A device used to capture a portion of the heat expelled from an air conditioning or heat pump compressor. It is used for domestic water heating, in essence providing "free" hot water.
Heat Transfer
The passage of heat from a warm body to a cooler one.
Heating Seasoned Performance Factor (HSPF)
Total heating output of a heat pump during its normal annual usage period for heating, divided by total electric power input during the same period.
High voltage
voltage greater than 100,000 volts.
Horsepower (hp)
A measure of power equal to about 746 watts.
Relating to water in motion.
Hydroelectric Plant
A facility at which the turbine generators are driven by falling water.
Hydroelectric Power
Capturing flowing water to produce electrical energy.
Hydroelectric Project
The complete development of a hydroelectric power site, including dams, reservoirs, transmission lines, and accessories needed for the maintenance and operation of the powerhouse and any other hydroelectric plant support facilities.
Hydrologic Unit Code (HUC)
Developed by the Water Resources Council corresponding to hierarchal classification of hydrologic drainage basins in the United States. Each hydrologic unit is identified by a unique hydrologic unit code (HUC).
The deeper cooler portions of a reservoir or lake that result from stratification.
hertz (cycles per second).


Illuminating Engineering Society of North America (IESNA)
The recognized technical authority in the lighting design industry, IESNA has established the guidelines to assure proper lighting design.
The body of water created by a dam.
Induced Surcharge Curve
A set of lake level elevations used to manage flows during periods of high inflow to ensure protection of downstream lands from flooding.
The undesirable flow of air into a building through cracks around doors, windows and other openings in the building. Infiltration is generally accompanied by exfiltration--flow out of the building.
Initial Information Package (IIP)
A document containing detailed information on a hydroelectric project; the document is used to describe the project and its resources and to start the applicant's consultation process with resource agencies and the public.
Installed Capacity
The nameplate MW rating of a generator or group of generators.
Integrated Licensing Process (ILP)
The ILP is the default process by which a hydropower project obtains a new license to operate.
Interested parties
Individuals who have expressed and interest in the relicensing proceeding.


Kilowatt (kW)
A unit for measuring electrical energy. One kilowatt is 1,000 watts and equal to 3,413 BTUs. A kilowatt-hour equals one kilowatt of electrical power taken from an electrical circuit steadily for one hour.
Kilowatt-hour (kWH)
Represents the use of 1,000 watts of electricity for one full hour. It is equivalent to 10 100 watt lightbulbs burned simultaneously and continuously for one hour.
Kilovolt (kV)
1,000 volts.
kVAR Charges (Reactive Power Charges)
Power factor is a measure of how effectively the current delivered to a motor is converted into useful energy. KVAR reflects the extent that current and voltage cycle in phase. The best and most efficient power factor is 100%, which occurs when current and voltage are perfectly in phase. kVAR is shown as a percentage.


Pertaining to or living in lakes or ponds.
Lake Rule Curve
A set of target lake level elevations that vary seasonally. The lake level is normally maintained at or below the elevations specified by the rule curve, except when storing floodwater. Rule curves are often set by federal agencies responsible for operating storage reservoirs, such as the Army Corp of Engineers.
Standing or still water including lakes, ponds and swamps.
FERC authorization to construct a new project or continue operating and existing project. The license contains the operating conditions for a term of 30 to 50 years.
License Application
Application for a new license; submitted to FERC no less than two years in advance of expiration of an existing license.
This is another term that refers to the Alabama Power Company (APC).
Light Loss Factor
LLF is used to create a safety margin to assure adequate lighting over a period of time. Good lighting design requires the designer to allow for the depreciation of a fixture’s light output due to dirt and age of the equipment. An LLF of 0.80 allows for a 20% degradation in the lighting level.
Associated with shallow (shoreline area) water (e.g., the littoral zone of an impoundment).
The total consumer demand of electric service at any given time.
The ability to change the amount of energy used at any given time. Load shifting can be accomplished by turning off a piece of equipment; switching to internal, off-grid power generation sources; or operation of equipment during off-peak hours.
Flowing or actively moving water including rivers and streams.
A measure of the amount of light given off by the lamp in a light fixture. A fixture with a higher level of lumens gives off more light.


The main channel of a river as opposed to the streams and smaller rivers that feed into it.
Martin Datum (MD)
Local datum of the Lake Martin project; equivalent to 491 ft mean sea level.
Maximum Drawdown Elevation
The lowest surface elevation to which a reservoir can be lowered and still maintain generation capability. This is usually somewhat lower than the minimum operating elevation.
Maximum Normal Operating Elevation
The maximum surface elevation to which the reservoir can be raised without surcharging or exceeding the license provisions.
Megawatt (MW)
A unit of electrical power equal to one million watts or 1,000 kW.
Megawatt-Hour (MWh)
A unit of electrical energy equal to 1 MW of power used for one hour.
Meter Constant
The number by which the total kWh in a billing cycle is multiplied to accurately reflect the number of kWh registered on the meter.
Minimum, Maximum and Average Foot-candles
Variables used to measure how evenly light is distributed in a given layout. As a rule, the lower the difference between the maximum and the minimum, the better the design. The Average figure is often used to indicate the overall lighting level in a given area. However, this figure inaccurately measures uniformity, since an area with very bright and very dark spots can average the same as an area with much more evenly distributed light.
Minimum Normal Operating Elevation
The lowest elevation to which a reservoir is normally lowered during power generation operations. Below this point power output and generation efficiency is significantly impacted.


Nameplate Capacity
A measurement indicating the approximate generating capability of a project or unit, as designated by the manufacturer. In many cases, the unit is capable of generating substantially more than the nameplate capacity since most generators installed in newer hydroelectric plants have a continuous overload capacity of 115 percent of the nameplate capacity. Also called Installed Capacity.
National Environmental Policy Act (NEPA)
A law passed by the U.S. Congress in 1969 to establish methods and standards for review of development projects requiring Federal action such as permitting or licensing.
Natural monopoly
when the cost of utility service, such as gas, water or electric service, is minimized to customers if a single enterprise is the only seller in the market.
Non-Governmental Organization (NGO)
Local, regional and national organizations such as conservation, sportsman's or commerce groups.
Normal Operating Capacity
The maximum MW output or a generator or group of generators under normal maximum head and flow conditions.
Normal Operating Elevation
The reservoir elevation approximating an average surface elevation at which a reservoir is kept.
Normal Operating Elevation Range
The elevation difference between the normal maximum and normal minimum operating elevations.


Occupancy Sensor
Sensing element that detects movement and controls power supply to the lighting unit.
A building that is built with a crawl space between the floor and the ground.
Off-system sales
sales by a utility to a customer (usually another utility) outside of its authorized market.
A building that is built on a cement slab directly on the ground.
Off Peak
A period of relatively low demand for electrical energy, such as the middle of the night.
On Peak
A period of relatively high demand for electrical energy.
The period during which a generating unit, transmission line, or other facility is out of service.


Palustrine Emergent Wetland
Contains rooted herbaceous vegetation that extend above the water surface (i.e., cattails, sedges).
Palustrine Forested Wetland
Dominated by woody vegetation less than 20 ft tall (i.e., willows, dogwood).
Palustrine Scrub/Shrub Wetland
Comprised of woody vegetation that is 20 ft tall or greater (i.e., American elm, swamp white oak).
Passive Solar
The design and siting of a building to maximize the effects of such natural processes as evaporation and heat flow, as opposed to active systems which require mechanical devices.
Peaking Operations
A power plant that is scheduled to operate during peak energy demand. Operation of generating facilities to meet maximum instantaneous electrical demands.
Macroscopic (visible without a microscope) and microscopic (visible only with a microscope) algae (single- and multi-celled plants) that grow on or attach to rocks, logs, and aquatic plants. Periphyton, phytoplankton, and aquatic plants are the primary producers that convert nutrients into plant material by the process of photosynthesis.
Microscopic single-celled and colonial forms of algae floating in the water column.
Ponding Operations
The process of storing and releasing water based on electric demand or flood control.
Peak Demand
A one hour period in a year representing the highest point of customer consumption of electricity.
A device that measures water pressure.
Plenary group
A group consisting of stakeholder representatives and APC to assist in decision making on the Coosa Warrior relicensing.
Refers to the reservoir or an impounded body of water.
The building that typically houses electric generating equipment.
Power Factor
The ratio of actual power to apparent power. Power factor is the cosine of the phase angle difference between the current and voltage of a given phase. Unity power factor exists when the voltage and current are in phase.
Power Pool
A regional organization of electric companies interconnected for the sharing of reserve generating capacity.
Pre-Application Document (PAD)
A document, required by FERC when relicensing a project, that brings together all existing, relevant, and reasonably available information about the project and its effects on resources; and includes a well-defined process plan that sets the schedule for developing the license application and a list of preliminary studies and issues.
Probable Maximum Flood (PMF)
A statistical formula used to calculate a hypothetical flood event that could occur on a particular river basin over a particular duration. This is derived from the probable maximum precipitation over time.
This refers to Alabama Power Company's Martin Hydroelectric Project, FERC Project No. 349.
Project Area
The geographic area defined in the license issued by FERC for the Project as needed for Project operations and maintenance.
Project Boundary
The boundary defined in the license issued by FERC for the Project outlining the geographic area needed for Project operations and maintenance.
Project Drainage Basins
The area of land that contributes surface water to the Tallapoosa River system.
Project Region
The area around the Project on the order of a County or National Forest in size.
Project Roads
Roads within Project Boundary and constructed for Project purposes and necessary for Project operation and maintenance.
Project Vicinity
The area extending to about five miles from the Project Boundary.
Project Viewshed
The area from which Project features are visible. The land base from which the Project may be seen.
Project Works
All of the infrastructure associated with the operations of the Project.
All of the relays and other equipment which are used to open the necessary circuit breakers to separate pieces of equipment from each other when trouble develops.
Protective Relay
A device whose function is to detect defective lines or apparatus, or other power system conditions of an abnormal or dangerous nature, and to initiate appropriate control circuit action.
Public Reference File
A listing of important materials pertaining to the relicensing.
Public Utility
A business enterprise rendering a service considered essential to the public and, as such, subject to regulation.


A measure of a substance's resistance to the transfer of heat. The higher the number, the greater the resistance.
Ramp Rate
The rate of change in output from a power plant. A maximum ramp rate is sometimes established to prevent undesirable effects due to rapid changes in loading or, in the case of hydroelectric plants, discharge.
The act of increasing or decreasing stream flows from a powerhouse, dam or division structure.
Ratchet Charges
Ratchet charges (also called Demand Charges) are based on your 12 month billing history, and is the demand rate used to calculate your charges. The purpose of Billed Demand charges is to reflect peak seasonal demands. Ratchet charges reflect either the maximum demand during the previous eleven months or the maximum demand during the previous summer months, or 100% of the current month's use — whichever is highest.
Reactive Power Charges (kVAR)
Power factor is a measure of how effectively the current delivered to a motor is converted into useful energy. KVAR reflects the extent that current and voltage cycle in phase. The best and most efficient power factor is 100%, which occurs when current and voltage are perfectly in phase. kVAR is shown as a percentage.
Real-Time Pricing (RTP)
Real-Time Pricing enables customers using very large amounts of energy to buy surplus energy real-time on the energy market at reduced rates.
A substance, such as Freon, which produces a cooling effect by absorption of heat while expanding or vaporizing.
Regulated Hydrology
The hydrology of Project-affected streams subsequent to construction of the Project.
The administrative proceeding in which FERC, in consultation with other federal and state agencies, decide whether and on what terms to issue a new license for an existing hydroelectric project at the expiration of the original license.
Relicensing Participants
Individuals who actively participate in the relicensing proceedings.
Reserve Capacity
Extra generating capacity available to meet unanticipated demand for power or to generate power in the event of loss of generation.
An artificial lake into which water flows and is stored for future use.
Reservoir Useable Capacity
A volume measurement of the amount of water that can be stored for generation, down to a minimum level.
Resident Fish
Fish that spend their entire life cycle in freshwater, such as sunfish and bass.
Resource Advisory Team
Groups consisting of stakeholders and APC designed to identify studies and work cooperatively to develop study scopes, review and comment on information and provide recommendations on project operations and protection and enhancement measures to the Plenary Group.
Resource Agency
A federal, state, or interstate agency with responsibilities in the areas of flood control, navigation, irrigation, recreation, fish or wildlife, water resource management, or cultural or other relevant resources of the state in which a project is or will be located.
Thermal and/or equipment improvements made to an existing building to increase the structure's energy efficiency.
Underground stem.
Riparian Area
A specialized form of wetland with characteristic vegetation restricted to areas along, adjacent to or contiguous with rivers and streams. Also, periodically flooded lake and reservoir shore areas, as well as lakes with stable water.
River Miles (RM)
Miles from the mouth of a river; for upstream tributaries, from the confluence with the main river.
A general term referring to upriver migration of anadromous fish over a particular time and area - often composed of multiple individual breeding stocks.
A term used to describe the operation of a hydroelectric project in which the quantity of water discharged from the project essentially equals the flow in the river.
The rotating part of a turbine.


Scoping Document 1 (SD1)
A document prepared by FERC as part of NEPA environmental review that initially identifies issues pertinent to FERC's review of a project. FERC circulates the SD1 and holds a public meeting to obtain the public's comment.
Scoping Document 2 (SD2)
A revision to SD1 which takes into account public comment on that document.
Scoping process
The process of identifying issues, potential impacts, and reasonable alternatives associated with the operation of a hydroelectric project. "Scoping" is a process required by any federal agency taking an action that might affect the quality of the human environment, pursuant to the National Environmental Policy Act (NEPA) of 1969. In the case of hydro projects, FERC's issuance of an operating license qualifies as a federal action.
Seasonal Energy Efficiency Ration (SEER)
A measure of the efficiency of an air conditioner or a heat pump, expressed as the ratio of output in BTUs to the energy input in watts.
Secchi Depth
Average depth at which a standard size black and white disk disappears and reappears when viewed from the lake surface as it is lowered. An indicator of water clarity.
The amount of water that leaks through a structure, such as a dam.
Service area
the territory in which a utility has the right to supply service.
Space Conditioning
The artificial heating or cooling of any space.
The act of fish releasing and fertilizing eggs.
Spawning Run
A general term referring to migration of anadromous or catadromous fish over a particular time and area.
A passage for releasing surplus water from a reservoir or canal.
Any individual or organization (government or non-governmental) with an interest in a hydroelectric project.
State of Alabama.
The introduction of a particular species of fish into an aquatic system as part of a resource management plan or goal.
The USEPA's computerized water quality data storage system.
A physical and chemical process that results in the formation of distinct layers of water within a lake or reservoir (i.e., epilimnion, metalimnion, and hypolimnion).
The rate at which water passes a given point in a stream, usually expressed in cubic ft per second (cfs).
Study Description
A detailed description of an individual study.
Study Plan
The aggregate of all study descriptions.
Submerged Aquatic Vegetation
Plants with rigid stems and/or leaves rooted in substrate and generally covered by deep water (greater than 6.6 ft depth), with all of the plant parts covered by water.
a facility where the voltage of electricity is reduced prior to distribution to customers.
Summary Billing
Charges for multiple facilities at different locations which go to a single payee can be aggregated into a single bill, called a Summary Bill.


The channel located between a hydroelectric powerhouse and the river into which the water is discharged after passing through the turbines.
The waters immediately downstream of a dam. For power dams, also referred to as the water discharged from the draft tubes.
Tainter Gate
A gate with a curved skin or face plate connected with steel arms to an axle. It is usually lifted or lowered by a cable connected to a hook at the top of the gate rotating on the axle as it is moved.
A means of referring to a set of animals or plants of related classification, such as all of the species (i.e., brook trout, lake trout) in a genus (trout); or all of the genera (all trout and salmon) in a family of fishes (salmonidae). Plural form of taxon is taxa.
Measure of gas that contains 100,000 BTUs. As there are approximately 1,000 BTUs per cubic foot of gas, there are approximately 100 cubic feet of gas per therm.
Using, producing, or caused by heat.
Thermal Envelope
The structural parts of a building that enclose the conditioned space and control the heat loss/gain of the building.
Time of Use (TOU) Rates
Lower rates sold on a long-term contract basis to customers with certain load patterns or those who have the flexibility to shift usage to off-peak periods, such as evenings, nights or weekends.
Equipment vital to the transmission and distribution of electricity designed to increase or decrease voltage.
The act or process of transporting electric energy in bulk from one point to another in the power system, rather than to individual customers.
Transmission Lines
Power lines normally used to carry high voltage electricity to substations which then is "stepped down" for distribution to individual customers.
The process by which water absorbed by plants is converted to vapor and discharged to the atmosphere.
Trash Rack
A series of vertical steel bars found on a dam or intake structure, which clears the water of debris before the water passes through the structure.
A measure of the extent to which light passing through water is reduced due to suspended materials.
A machine for generating rotary mechanical power from the energy in a stream of fluid (such as water, steam, or hot gas). Turbines convert the energy of fluids to mechanical energy through the principles of impulse and reaction, or a mixture of the two.


A measure of how evenly or "smoothly" the lighting level is spread out over an area. It is expressed as a Uniformity Ratio, where the average foot-candles measure is divided by the minimum foot-candles. The lower this ratio, the better.


Vapor Barrier
A building material that resists the passage of invisible moisture in the air. Barriers are usually plastic film, metallic foil or asphalt-coated felt.
Vantage Point
The location from which a viewer sees the landscape.
Any opening in a building designed for the flow of air or moisture.
The process of supplying or removing air by natural or mechanical means to or from any space. Such air may or may not have been conditioned.
Volt (V)
The unit of electromotive force or electric pressure, akin to water pressure in pounds per square inch.


Warmwater Fish
Fish species typical of southeastern warm water environments (e.g., bass, sunfish, pickerel, sucker).
An entire drainage basin including all living and nonliving components of the system.
An electrical unit of power or rate of doing work. It is analogous to horsepower or foot-pounds per minute of mechanical power. One horsepower equals 746 watts.
Foam, metal or rubber strips used to form a seal around windows and doors to reduce infiltration.
Lands transitional between terrestrial and aquatic systems where the water table is usually at or near the surface or the land is covered by shallow water. Wetlands must have the following three attributes: 1) at least periodically, the land supports predominantly hydrophytes; 2) the substrate is predominantly undrained hydric soil; 3) the substrate is on soil and is saturated with water or covered by shallow water at some time during the growing season of each year.


Microscopic and macroscopic animals that swim in the water column. These invertebrates include chiefly three groups: rotifers, cladocerans, and copepods.