Definition List
- CFS
- A measurement of water flow equivalent to one cubic foot of water passing a given point for an entire second. One KCFS equals a 1,000 CFS.
- Discharge
- Volume of water released from a dam, powerhouse or spillway, at a given time, measured in cubic feet per second (CFS).
- Energy Northwest
- Energy Northwest (formerly known as the Washington Public Power Supply System) was formed in 1957, consists of 19 public utility districts and 4 municipal electric systems in the State of Washington, and is a municipal corporation for the purpose of jointly building and operating generating projects, such as the Columbia Generating Station nuclear plant (formerly known as WNP-2). BPA provides oversight on this project.
- Federal Columbia River Power System (FCRPS)
- The hydroelectric multipurpose facilities constructed and operated by the U.S. Army Corps of Engineers and the Bureau of Reclamation in the Pacific Northwest and the transmission system constructed and operated by BPA used to market and deliver electric power whose costs are funded and repaid through BPA power and transmission rates.
- Forebay
- The portion of a reservoir at a hydro project that is immediately upstream from a dam. It is measured in feet above sea level.
- Maximum Forebay
- The maximum reservoir elevation on the forebay side of a dam.
- Minimum Forebay
- The minimum reservoir elevation on the forebay side of a dam.
- Hydraulic Head
- The vertical distance, measured in feet between the surface of the reservoir and the surface of the river immediately downstream. One foot is equal to 0.305 meters.
- MAF
- Million acre feet. The equivalent volume of water that will cover an area of one million acres to a depth of one foot. One MAF equals 1,000 KAF.
- MW Rating
- The maximum generating capacity of the unit, measured in megawatts (MW).
- Operator
- The organization that operates and maintains a particular project. Federal dams were built and are operated by the U.S. Army Corps of Engineers (COE) or the U.S. Bureau of Reclamation (USBR).
- Portion of Cost Allocated to Power
- The cost allocated to the power generating portion of hydro projects. Flood control, navigation, and irrigation are non-power activities associated with hydro project operations, and not included in the cost allocated to power. O&M costs are ongoing costs to the hydro project for routine operations and maintenance; capital costs are costs associated with initial construction and any new major additions to the hydro project.
- Powerhouse
- The electricity generating portion of a hydroelectric project.
- Powerhouse Hydraulic Capacity
- The maximum rate of water flow that can be used for generating power, and is measured in cubic feet per second (CFS).
- Precipitation
- Amount of rain and snowfall for the period, measured in inches (one inch is equal to 2.54 centimeters).
- Reservoir Storage
- The volume of water in a reservoir, or group of reservoirs, at a given time measured in thousand acre feet (KAF) or million acre feet (MAF).
- Runoff Forecast
- The forecast of total volume expected to appear as river runoff, measured at a particular location. It includes actual cumulative runoff to date, estimated runoff attributed to remaining snowpack, and future average precipitation, and is measured in million acre feet (MAF). An important forecast is made for The Dalles for the January-July period.
- Run-of-river dams
- Hydroelectric generating plants that operate based only on available inflow and a limited amount of short-term storage.
- Spillway
- Overflow structure of a dam. Water passed over a spillway, or spill, can be forced, when there is not enough storage capability and flows exceed turbine capacity, or planned, when water is spilled to enhance juvenile fish passage.
- Spillway Hydraulic Capacity
- The maximum rate of water flow possible through the spillway, and is measured in cubic feet per second (CFS).
- Storage reservoirs
- Reservoirs that have space for retaining water from springtime snowmelts. Retained water is released as necessary for multiple uses -- power production, fish passage, irrigation, and navigation.
- Streamflow
- The rate at which water passes a given point, measured in cubic feet per second (CFS).
- Subagreement
- Refers to direct funding arrangements offered by BPA to the COE- and USBR-owned and operated hydro projects. These subagreements allow BPA to directly fund efficiency improvements and other maintenance associated with power production at hydroelectric facilities.
- Tailwater
- Water immediately below the power plant. Tailwater elevation refers to the level of that water, which can rise as discharges increase. It is measured in feet above sea level (one foot is equal to 0.305 meters).
- U.S. Army Corps of Engineers
- The U.S. Army Corps of Engineers (COE) owns and operates 21 of the 31 hydro projects featured here. It is responsible for flood control at all major reservoirs in the Columbia River Basin and maintains navigation channels, as well as operating and maintaining the nation's water and related environmental resources. Click here to view COE, North Pacific Division Home Page (http://www.nwd.usace.army.mil) in a new window.
- U.S. Bureau of Reclamation
- Bureau of Reclamation (USBR) owns and operates 10 of the 31 hydro projects featured here. It operates water resource projects throughout the Columbia River Basin for irrigation and other uses. It is an agency of the U.S. Department of Interior (DOI), the nation's principal conservation agency. DOI has responsibility for most of our nationally owned public lands and natural resources. Click here to view USBR Home Page (http://www.usbr.gov/pn/) in a new window.
- Unit Availability
- Indicates whether a generating unit is available for generation -- it represents the potential use of generation units, and not actual, real-time operations.
- Washington Public Power Supply System (WPPSS)
- See Energy Northwest
Page content last modified on: October 19, 2006.
Content provided by: Matthew Dau, 503-230-3961, mrdau@bpa.gov.
Page maintained by: BPA Web Team.
