Biological growthThe activity and growth of any and all living organisms.
Biological magnification (biomagnification)Step by step concentration of substances in successive levels of food chains. The enhancement of a substance (usually a contaminant) in a food web such…
Biological Opinion (BO)Document stating the U.S. Fish and Wildlife Service (FWS) and the National Marine Fisheries Service (NMFS) opinion as to whether a Federal action is…
Biological processesProcesses characteristic of, or resulting from, the activities of living organisms.
BiomassThe aggregate amount of living matter or a specific species within a specific habitat, or the total number of a specific species in a specific habitat.
BiosphereThe part of the earth and its atmosphere that is inhabited by living organisms.
BiotaThe animal and plant life of a region or period.
Biotic potentialInherent capacity of an organism to reproduce and survive, which is pitted against limiting influences of the environment.
Biotic pyramidSet of all food chains or hierarchic arrangements of organisms as eaters and eaten in a prescribed area when tabulated by numbers or by biomasses, usually…
Black IceTransparent ice formed in rivers and lakes, or on roads and bridges.
Black waterLiquid and solid human body waste and the carriage water generated through toilet usage.
BlackoutThe disconnection of the source of electricity from all the electrical loads in a certain geographical area brought about by an emergency forced outage or…
bladeUsually a part of an excavator which digs and pushes dirt but does not carry it.
BONThe necrosis (death) of bone tissue caused by treatment with a bisphosphonate (a drug or substance used to treat osteoporosis, bone pain caused by some…
BonnetThe upper portion or the cover of a gate valve body.
Bonneville Power Administration (BPA)One of five federal power marketing administrations that sell low cost electric power produced by federal hydro electric dams to agricultural and…
BorrowMaterial excavated from one area to be used as fill material in another area.
Borrow areasGenerally, surface areas, that contain borrow pits. The area from which material for an embankment is excavated.
Borrow pitsSpecific site(s) within a borrow area from which material is excavated for use.
BoulderA rock fragment, usually rounded by weathering or abrasion, with an average dimension of 12 inches or more: will not pass a 12-inch screen.
Boulder clayA geological term used to designate glacial drift that has not been subjected to the sorting action of water and therefore contains particles from…
Box girderA hollow steel beam with a square or rectangular cross section.
BPA- Bonneville Power Administration, blanket purchase agreement.
BrackishWater of intermediate salinity between seawater and freshwater.
Braided StreamCharacterized by successive division and rejoining of streamflow with accompanying islands. A braided stream is composed of anabranches.
BRAINBureau of Reclamation Acquisition Information Network.
Brake horsepowerThe brake horsepower of a pump is the actual motor input horsepower required to produce the hydraulic horsepower from a pump (flow and head) taking into…
BranchAn addition to the main pipe in a piping system.
Brash IceAccumulation of floating ice made up of fragments not more than 2 meters across; the wreckage of other forms of ice.
BRC- Budget Review Committee, Bureau Procurement Chief.
BreakupThe time when a river whose surface has been frozen from bank to bank for a significant portion of its length begins to change to an open water flow…
Breakup DateDate on which a body of water is first observed to be entirely clear of ice and remains clear thereafter.
Breakup JamIce jam that occurs as a result of the accumulation of broken ice pieces.
Breakup PeriodThe period of disintegration of an ice cover.
Breccia (volcanic breccia)Conglomerate-like rock made up of angular pieces of volcanic rock usually bound in volcanic ash.
BrecciatedA rock made up of highly angular, coarse fragments.
Breeding densityDensity of sexually mature organisms in a given area during the breeding period.
Breeding potentialMaximum rate of increase in numbers of individuals of a species or population under optimum conditions.
Breeding rateActual rate of increase of new individuals in a given population; the breeding potential minus limiting factors.
Bridge, Class AA bridge located on a Federal-aid highway. Examination of this type of bridge is required every 2 years with an in-depth examination every 6 years.
Bridge, Class BA bridge not located on a Federal-aid highway that is used by the public. Examination of this type of bridge is required every 3 years.
Bridge, Class CA bridge not located on a Federal-aid highway that can be designated as being a private or operating bridge and could be gated or closed to the public, if…
British thermal units (Btu)Quantity of heat required to raise the temperature of one avoirdupois pound of water 1 degree F at or near 39.2 degrees F.
BRMbusiness reference model - an organized, hierarchical way to describe the day-to-day business operations of the Federal government; this model presents…
Broad-crested weirAn overflow structure on which the nappe is supported for an appreciable length in the direction of flow. See weir.
BrownoutThe partial reduction of electrical voltages. A brownout results in lights dimming and motor-driven devices slowing down. See blackout.
Bubbler GageA water stage recording device that is capable of attaching to a LARC for data automation purposes.
bucketA part of an excavator which digs, lifts, and carries dirt.
Budget Review Committee (BRC)An ad hoc committee of representatives from each Region, the Reclamation Service Center, and the Washington Office, coordinates Reclamation budget…
Built EnvironmentThe urban environment consisting of buildings, roads, fixtures, parks, and all other improvements that form the physical character of a city.
BulkheadThe part of a storefront that forms a base for one or more display windows
Bulkhead GateA gate used either for temporary closure of a channel or conduit before dewatering it for inspection or maintenance or for closure against flowing water…
BulkingThe increase in volume of a material due to manipulation. Rock bulks upon being excavated; damp sand bulks if loosely deposited, as by dumping, because…
BurdenIn blasting, the distance between the free face and the first row of holes or the distance between rows of holes parallel to the face.
Bureau of Indian Affairs (BIA)The Bureau of Indian Affairs' mission is to enhance the quality of life, to promote economic opportunity, and to carry out the responsibility to protect…
Bureau of Land Management (BLM)The Bureau of Land Management, an agency within the U.S. Department of the Interior, administers 264 million acres of America's public lands, located…
Bureau of Reclamation (USBR, Reclamation, BOR)The mission of the Bureau of Reclamation is to manage, develop, and protect water and related resources in an environmentally and economically sound…
Bus (buswork)A conductor, or group of conductors, that serve as a common connection for two or more electrical circuits.
BusbarThe power conduit of an electric power plant; the starting point of the electric transmission system.
Butterfly valveA valve designed for quick closure that consists of a circular leaf, slightly convex in form, mounted on a transverse shaft carried by two bearings.
Buttress DamA dam consisting of a watertight upstream part (such as a concrete sloping slab) supported at intervals on the downstream side by a series of buttresses…