Wall frictionFrictional resistance mobilized between a wall and the soil or rock in contact with the wall.
Warm-water fisheryGenerally, water or water system that has an environment suitable for species of fish other than salmonids.
WarningThe fourth of five Early Warning System components consisting of the processes (including the media) and equipment necessary to make the public aware of…
Warning stageThe depth of water in a river at which the National Weather Service (NWS) reviews basin conditions for potential flooding.
Warning time (WT)The amount of time between detection of failure or incipient failure and arrival of dam failure flood.
Wash loadThat part of the total sediment discharge which is composed of particle sizes finer than those found in appreciable quantities in the bed material, and is…
WasteDigging, hauling and dumping of valueless material to get it out of the way; or the valueless material itself.
WastebankA bank made of excess or unstable material excavated from a construction site.
Water cycleThe movement of water from the air to and below the Earth's surface and back into the air. See hydrologic cycle.
Water delivery systemReservoirs, canals, ditches, pumps, and other facilities to move water.
Water demandWater requirements for a particular purpose, as for irrigation, power, municipal supply, plant transpiration or storage.
Water EquivalentThe amount of water, in inches, obtained by melting a snow sample.
Water hammer (hydraulic transient)Refers to pressure fluctuations caused by a sudden increase or decrease in flow velocity, usually associated with a rapid closure or opening of a valve in…
Water holding capacityAmount of soil water available to plants. See available capacity. The smallest value to which the moisture content of a soil can be reduced by gravity…
Water management planA plan developed during construction to help assure water quality compliance for both point and nonpoint pollution sources.
Water Measurement ManualThe Bureau of Reclamation's Water Measurement Manual is available on line at the Water Resources Research Laboratory's website.
Water PollutionThe alteration of the constituents of a body of water by man to such a degree that the water loses its value as a natural resource.
Water qualityA term used to describe the chemical, physical, and biological characteristics of water, usually with respect to its suitability for a particular purpose.
Water saturationThat point at which a material will no longer absorb water.
Water supplierA person who owns or operates a public water system.
Water Supply OutlookA seasonal volume forecast, generally for a period centered around the time of spring snowmelt (e.g., April-July).
Water Supply Outlook (ESS) ProductA public product issued by a Forecast Office which contains narrative and numeric information on current and extended water supply conditions.
Water surface elevation (stage)The elevation of a water surface above or below an established reference level, such as sea level. See datum.
Water TableThe upper level of ground water; the level below which soil and rock are saturated with water.
Water transfersSelling or exchanging water or water rights among individuals or agencies. Artificial conveyance of water from one area to another.
Water userAny individual, district, association, government agency, or other entity that uses water supplied from a Reclamation project.
Water YearThe time period form October 1 through September 30.
Water year (WY)Period of time beginning October 1 of one year and ending September 30 of the following year and designated by the calendar year in which it ends.
WatercourseAny surface flow such as a river, stream, or tributary.
WatershedAll land area from which run-off water may enter a pond or lake.
Watershed (drainage area)Surface drainage area above a specified point on a stream. Area which drains into or past a point.
Watershed divideThe divide or boundary between catchment areas (or drainage areas).
Waterstage recorderA motor-driven (spring wound or electric) instrument for monitoring water surface elevation.
WaterstopA strip of metal, rubber or other material used to prevent leakage through joints between adjacent sections of concrete.
Waterstop (water bar)A continuous strip of waterproof material placed at concrete joints designed to control cracking and limit moisture penetration.
WattThe rate of energy transfer equivalent to one ampere under an electrical pressure of one volt. One watt equals 1/746 horsepower, or one joule per second.
Watt hour(Wh)An electrical energy unit of measure equal to one watt of power supplied to, or taken from, an electrical circuit steadily for one hour.
Wave runupVertical height above the sill water level to which water from a specific wave will run up the face of a structure or embankment.
WeirAn overflow structure built across an open channel to raise the upstream water level and/or to measure the flow of water.
WeldTo build up or fasten together metals by bonding on molten metal.
WellA hole or shaft drilled into the earth to get water or other underground substances.
Well fieldArea containing one or more wells that produces usable amounts of water.
Well gradedA good representation in the material of all particle sizes present from the largest to smallest.
WellpointA pipe fitted with a driving point and a fine mesh screen used to remove underground water.
Western Area Power Administration (WAPA)The Western Area Power Administration markets and delivers reliable, cost-based hydroelectric power and related services within a 15-state region of the…
Western Systems Coordinating Council (WSCC)The Western System Coordinating Council is a voluntary industry association created to enhance reliability amoung western utilities.
Wet FloodproofingAn approach to floodproofing which usually is a last resort. Flood waters are intentionally allowed into the building to minimize water pressure on the…
Wet unit weightThe unit weight of solids plus water per unit volume, irrespective of the degree of saturation.
WetlandArea covered all or part of the year by water. Can be identified by typical plants and soil types.
WetlandsArea having specific hydric soil and water table characteristics supporting or capable of supporting wetlands vegetation.
Wetted perimeterThe distance along the bottom and sides of a stream, creek, or channel in contact with the water.
WheelingThe process of transmitting electricity over one or more separately owned electric transmission and distribution systems.
White noiseRandom energy containing all frequency components in equal proportions.
Wholesale customersAny entity that purchases electricity at the wholesale level, including municipal utilities, private utilities, rural electric cooperatives, or…
Wholesale power marketThe purchase and sale of electricity from generators to resellers (who sell to retail customers) along with the ancillary services needed to maintain…
Wholesale transmission servicesThe transmission of electric energy sold, or to be sold, at wholesale in interstate commerce.
Wholesale WheelingThe wheeling of electric power in amounts and at prices that generally have been negotiated in long term contracts between the power provider and a…
Wicket gateIn hydropower applications a gate which pivots open around the periphery of a turbine or pump to allow water to enter.
Wild and Scenic Rivers Act (Public Law 90-542)The Wild and Scenic Rivers Act selects certain rivers possessing remarkable scenic, recreational, geologic, fish and wildlife, historic, or other similar…
WildernessAll lands included in the National Wilderness Preservation System by public law, generally defined as undeveloped federal land retaining its primeval…
Wilderness resourceResources identified in officially designated wilderness areas on Forest Service or Bureau of Land Management administered land.
Wildlife RefugeAn area designated for the protection or replenishment of wild animals, within which hunting and fishing are either prohibited or strictly controlled.
Willingness to payMethod of estimating the value of activities, services, or other goods, where value is defined as the maximum amount a consumer would be willing to pay…
Wilting pointThe moisture content of soil at which plants start to wilt, but not to the extent that they fail to recover when placed in a humid atmosphere.
WinchA drum that can be rotated so as to exert a strong pull while winding in a line.
Wind setupThe vertical rise in the still water level at the face of a structure or embankment caused by wind stresses on the surface of the water.
Wing wallA wall that guides a water into a conveyance structure.
Winters DoctrineProvides that the establishment of a Indian Reservation impliedly reserves the amount of water necessary for the purposes of the reservation.
Wire Weight GageA river gage comprised of a weight which is lowered to the water level. The weight is attached to a cable; and as the weight is lowered, a counter…