一个

邻接： 山谷边缘上修建大坝的部分。有时在没有合适的天然桥台的地方会修建人工桥台。右桥台和左桥台是观察者从下游看时分别位于观察者两侧的桥台。泄洪道或闸门结构与堤坝之间的墙也可以称为桥台。

适应性管理计划： 一套管理实践系统，以明确确定的时间框架和结果为基础，通过监测来确定管理行动是否符合结果，如果没有，则促进管理变革，以确保及时实现结果或重新评估结果。适应性管理认识到，关于自然资源系统的知识有时是不确定的，因此在这些情况下，适应性管理是首选的管理方法。

曝气器： 强制空气系统用于对发电站下游释放的水进行重新充气。

安伯森大坝： 一种支墩坝，其上游部分是相对较薄的平板，通常由钢筋混凝土制成。

溯河洄游鱼类： 鱼的生命周期始于淡水，然后以幼鱼身份迁徙到海洋，在那里长大成鱼，然后再迁回淡水产卵。

斜角杆架： 斜角栅栏和百叶窗用于引导下游迁徙的鱼类流向旁路和泄水道，而不是通过水电站。这些结构引导系统不会从物理上将鱼类排除在发电站进水口之外，而是在结构前创造水力条件，以阻止鱼类进入进水口。

附属设施： 指变电站、输电线路等水电设施的非整体部分。

拱坝： 一种混凝土、砖石或木结构大坝，其轴线向上游弯曲，以便将大部分水负荷传递到桥台。这种大坝类型类似于重力结构，但拱坝利用狭窄的上游曲线将水压引导到海岸线上，提供压缩和维持大坝强度的力量。

景点流程： 在鱼道上游或下游入口处供应的辅助水，可产生足够强的水力信号，使鱼能够感知到鱼道路线并及时通过，从而避免不必要的延误、疲劳、受伤和/或死亡。

轴流涡轮机： 水流方向与涡轮轴平行的涡轮机。

乙

开合门： 用于调节水坝水流量的可调节闸门。这种闸门降低时打开，升高时关闭。

基流（水生基流）： 水生基流这一术语由美国鱼类和野生动物管理局创造，用于描述一组化学、物理和生物条件，这些条件代表了溪流环境中水生生物和野生动物的限制条件。从水文角度来说，它是指美国鱼类和野生动物管理局计算出的 8 月中值流量。

流域规模（或流域范围）： 流域规模或流域范围涵盖在河流及其支流流经的土地区域内发生的活动。

浴缸溢洪道： 双侧槽溢洪道。

护堤： 堤坝斜坡剖面中近乎水平的台阶。也指岩石或土方开凿的台阶。

分叉： 分成兩個分枝。

布鲁姆门： 一种安装在滚轮上的垂直升降门，两侧均由不锈钢滚轮链支撑。

棕地： 由于存在或潜在存在危险物质、污染物或污染物，其扩建、再开发或再利用可能会变得复杂。

灯泡式涡轮机： 轴流式螺旋桨涡轮机，其中涡轮机和发电机是一个密封单元，直接放置在水流中。

蝶阀： 一种阀门机构，通过阀盘的四分之一圈旋转来调节大管径内材料的流动。蝶阀是一种四分之一圈阀门。它的工作原理与球阀类似，可快速关闭，但与球阀不同的是，蝶阀还可以逐步打开和关闭。这种差异意味着阀盘始终存在于流体中，并允许压力下降。

支柱坝： 钢筋混凝土支撑结构通过单独的支撑基础将水负荷转移到地基岩石，利用蓄水的重量和结构的重量来抵抗滑动和倾覆。

旁路： 穿过或绕过水坝的渠道或管道，用于提供河水流量以及供鱼类通过的路线，而无需经过涡轮机组。

绕过范围： 水道中，通过涡轮机或其他机械方式将水引向水力发电的初始点，与水被释放到涡轮机或其他机械发电方式下方的水道中的点之间的区域。

碳

运河： 一种人工建造的明渠，通常用于将水从水库输送到发电站。

降水洄游： 鱼类的生命周期始于海水，幼鱼迁徙至淡水，长成成鱼后再迁回海洋产卵。美洲鳗是北美洲唯一的降水洄游鱼类。

CERCLA（超级基金法案）： 《综合环境反应、补偿和责任法案》（CERCLA），通常称为“超级基金”，由国会于 1980 年 12 月 11 日颁布。该法律对化学和石油工业征税，并赋予联邦政府广泛的权力，以直接应对可能危害公众健康或环境的危险物质的排放或威胁排放。

保护地役权： 土地所有者与土地信托或政府机构之间自愿达成的法律协议，永久限制土地的使用，以保护其保护价值。土地所有者保留许多权利，包括拥有和使用土地、出售土地和将其传给继承人的权利。

消耗性取水量： 因蒸发、工厂和工业过程而损失的水量。

顶门： 泄洪道顶部的闸门，用于控制泄洪或水库水位。这些闸门底部装有铰链，可通过从垂直旋转到水平来打开。

横流涡轮机： 横流式涡轮机呈鼓形，使用细长的矩形截面喷嘴，喷嘴朝向圆柱形转轮上的弯曲叶片。横流式涡轮机允许水流过叶片两次。第一次通过时，水从叶片外部流向内部；第二次通过时，水从内部流回外部。涡轮机入口处的导叶将水流引导到转轮的有限部分。

德

坝： 用于阻挡水、废水或任何液体物质的屏障，用于储存或控制水。

滴滴涕： 二氯二苯三氯乙烷是 20 世纪 40 年代开发的第一种现代合成杀虫剂。它最初在军人和平民中用于对抗疟疾、斑疹伤寒和其他昆虫传播的人类疾病，效果显著……美国农业部在 20 世纪 50 年代末和 60 年代开始采取监管行动，禁止使用 DDT，因为越来越多的证据表明这种杀虫剂的效益正在下降，并且对环境和毒理学有影响。1972 年，美国环保署发布了 DDT 的取消令，理由是 DDT 对环境有不利影响，例如对野生动物的影响，以及对人类健康有潜在风险。此后，研究仍在继续，根据动物研究，人们怀疑 DDT 暴露与人类生殖影响之间存在关联。

特拉华式鳗鱼梯： 通过在水坝顶部附近的挡水板、水面闸门或其他结构上开一个洞来建造一条上游鳗鱼通道。通过将拖网或类似的绳状材料穿过洞（并可选地套上一段 PVC 管来控制水流），为鳗鱼越过水坝创建一条粗糙的路线。

丹尼尔风格鱼道： Denil 设计是一系列挡板式滑槽梯子，利用粗糙元素（即挡板）来消散水流经水槽的动能，为洄游鱼类创造一个低速通道区。

海洄游动物： 洄游鱼类是描述生命周期中一部分在淡水中，一部分在咸水中度过的鱼类的一般类别。这些鱼类既包括溯河洄游鱼类，也包括降河洄游鱼类。

二恶英： 二恶英是指一组具有某些共同化学结构和生物特性的有毒化合物。二恶英毒性极强，可导致癌症、生殖和发育问题、免疫系统受损，并可干扰荷尔蒙。

导流： 通过运河、管道、水井或其他管道将溪流、湖泊、含水层或其他水源的水转移到另一条水道或陆地，例如灌溉系统。

引水坝： 为将一条水道或溪流的水转移到另一条水道而建造的水坝。

双曲拱坝： 垂直和水平方向均弯曲的拱坝。

导流管： 将水从水轮机转轮输送到尾水的管道。设计用于最大程度提高水头和发电量。

埃

土坝： 总体积的 50% 以上是由压实土层构成的土石坝，这些土层通常小于 3 英寸。

鳗鱼梯/鳗鱼坡道/鳗鱼道： 倾斜的水槽，水从水坝上方流向下方，鳗鱼利用该水槽爬上水坝。

土石坝： 通过放置和压实由各种成分的土壤、沙子、粘土和/或岩石组成的复杂半塑性土堆而形成的巨大水坝，通常具有致密的不透水核心。

夹带： 无意中被吸入发电站进水口结构并穿过涡轮机的鱼。

基本鱼类栖息地： 根据《马格努森-史蒂文斯渔业保护和管理法》，EFH 适用于联邦管理的物种。EFH 包括这些受管理鱼类产卵、繁殖、觅食或成长的所有类型的水生栖息地。

河口： 淡水与咸水交汇的区域。高生产力的生态系统。

豁免： 豁免是指对环境影响有限且符合某些标准的小型水电项目，因此根据《联邦电力法》第一部分可免于许可。豁免是永久性的，包括州和联邦鱼类和野生动物机构规定的强制性环境条款和条件。

已拔除： 从设施受影响的区域中彻底清除或局部消灭某个物种种群。

弗

虚假吸引力流： 水流或湍流妨碍了鱼找到上游或下游鱼道的能力。涡轮机排放流、大坝溢流或大坝闸门的运行都可能导致假引流。

动物： 某个地区或栖息地的动物种类。

联邦能源管理委员会： 联邦能源管理委员会 - 负责监管和监督州际天然气、石油和电力输送以及天然气和水电项目的独立联邦机构。

鱼类通道： 鱼类安全有效地沿人工障碍物上游和下游移动的能力。

鱼屏： 安装这种屏障是为了将鱼从运河或发电站的进水口或出水口转移出去。

鱼道： 鱼类穿越障碍物所必需的要素（结构、设施、设备、操作和措施）的组合。

闪光板： 放置在水渠中或泄洪道顶部的木材、混凝土或钢结构构件，用于提高水库水位，但旨在发生洪水时快速移除、绊倒或损坏。

闸： 控制水库泄洪的闸门。

洪泛平原森林： 洪泛平原森林通常出现在河流沿岸低洼且易发生洪泛的地区，通常高出河道 20 英尺以下。它们通常与牛轭湖（与河道分离的水池）、夏季干涸的临时湿地（春池）、长满草和野花的开阔草地以及茂密的灌木丛有关。

洪泛区： 洪泛平原是指河流或溪流旁的一块平坦土地。

植物： 特定地区或栖息地的植物种类。

流动持续时间曲线： 流量持续时间曲线是一种图表，显示河流流量可能等于或超过某个指定值的时间百分比。例如，它可用于显示河流流量预计超过某个指定值（例如 20 cfs）的设计流量的时间百分比，或显示发生或超过一定时间百分比（例如 80% 的时间）的河流流量。

水槽： 一种人工结构，用于输送水，其形式为开放式、倾斜的重力溜槽，其壁高于周围地形。

Forebay: The impoundment immediately upstream of a dam or hydroelectric plant intake structure.

Francis Turbine: The Francis turbine is a reaction turbine, which means it develops power from the combined action of pressure and moving water. The runner is placed directly in the water stream so the water is flowing over the blades rather than striking each individually. A Francis turbine has a runner with fixed blades, usually nine or more. Water is introduced just above the runner and all around it which then falls through, causing the blades to spin. Besides the runner, the other major components include a scroll case, wicket gates, and a draft tube. The Francis turbine was the first modern hydropower turbine and was invented by British-American engineer James Francis in 1848 and first used at the Lowell Hydroelectric Project (LIHI #142) in Massachusetts.

Freshet: Spring thaw of snowpack and ice that runs off into a water body in a short period of time.

G

Gate: A structure, typically on a dam or canal, that allows passage of water when open.

Governor: The device which measures and regulates turbine speed by controlling wicket gate angle to adjust water flow to the turbine.

Gravity Dam: Constructed from concrete or stone masonry and designed to hold back water by primarily using the weight of the dam itself to resist the horizontal pressure of water pushing against it.

H

Head: Head is the difference between the water surface elevations upstream (the reservoir) and downstream of a project (the tailrace), providing the energy for the falling water.

Headgate: A gate that controls water flow into a canal, sluiceway or powerhouse intake.

Headwaters: The initial source of a river or stream.

Helical: 螺旋。

Hollow Gravity Dam: 大坝外部由混凝土和/或砖石建造，但内部是空心的，依靠其重量保持稳定性。

Hydraulic Fill Dam: 用通常疏浚过的材料建造的土坝，通过悬浮在流水中的方式输送和放置。

I

Impingement: The physical contact of a fish with an intake structure (such as a trash rack or fish screen) due to water velocities that are too high to allow the fish to swim away.

Impoundment: 通过建造障碍物（如水坝和导流设施）形成的水体。通常用于指径流设施。

Inflatable flashboards: 固定在水坝顶部的充气结构，用于管理蓄水水位。

Inflow: 特定时间段内流入水库或前池的水的速率或水量。

Instream Flow Incremental Methodology: A science-based habitat evaluation technique that is a quantitative environmental assessment procedure that describes how habitat quantity and quality change over a range of physical conditions, such as stream flows or impoundment surface elevations. The term refers to a relatively large number of assessment methods. The most important aspect of these techniques is that they involve an analytical framework that considers the tradeoffs between multiple ecological processes and resource management objectives and evaluates a range of flow options over a continuum of hydrologic conditions.

Instream Flows: Water volumes and levels in a stream needed to support aquatic life, water quality, consumptive uses or recreation, synonymous with other commonly used terms such as ‘environmental’ flow and ‘ecological’ flow.

Intake: 通向管道/压力水管的结构。可与发电站集成，将水引至涡轮机。

K

Kaplan Turbine: A Kaplan turbine is a reaction propeller-type turbine which generates power from the combined forces of pressure and moving water. A runner is placed directly in the water stream, allowing water to flow over the blades rather than striking each individually. In a Kaplan turbine both the blades and the wicket gates are adjustable, allowing for a wider range of operation. This turbine was developed by Austrian inventor Viktor Kaplan in 1919.

L

Leakage Flow: 水通过水坝或引水建筑物的孔洞或裂缝，或者通过挡水板而不受控制地流失。

Littoral: 水体中靠近海岸的区域，阳光可到达其中的沉积物，支持水生植物的生长。

Load Following: 根据电力需求，全天调整发电量。

Louver Racks: Angled bar racks and louvers are used to direct fish toward bypasses and sluiceways at hydropower plants. These structural guidance systems are devices that do not physically exclude fish from intakes, but instead create hydraulic conditions in front of the structures to divert fish away from the intakes.

M

Masonry Dam: A dam constructed mainly of stone, brick, or concrete blocks pointed with mortar. A dam having only a masonry facing should not be referred to as a masonry dam.

Minimum Flow: The minimum flow that must be released from a project in order to meet environmental or other non-power water requirements. Flows are released either to a bypassed reach or downstream of the project.

MOA: Memorandum of Agreement - a document written between parties to cooperatively work together on an agreed upon project or meet an agreed upon objective.

MOU: Memorandum of Understanding - a document describing a bilateral agreement between parties.

Multiple Arch Dam: A buttress dam comprised of a series of arches for the upstream face.

N

National Geodetic Vertical Datum: NGVD - A vertical datum is a surface of zero elevation to which heights of various points are referenced. The NVGD of 1929 was utilized until it was superceded in 1992 to be replaced with the North American Vertical Datum of 1988 for the contiguous US and Alaska.

National Register of Historic Places: The National Register of Historic Places is the official list of the Nation's historic places worthy of preservation. Authorized by the National Historic Preservation Act of 1966, the National Park Service's National Register of Historic Places is part of a national program to coordinate and support public and private efforts to identify, evaluate, and protect America's historic and archeological resources.

Nature-like Fishway: Nature-like fishways mimic natural side channels and are placed next to migration barriers. They include a wide variety of designs such as step‐pools, roughened ramps, rock‐arch rapids, rocky riffles, and cross vanes which are typically constructed of boulders, cobble, and other natural materials to create diverse physical and hydraulic conditions providing efficient passage to multiple species of migratory and resident fish.

NGVD: National Geodetic Vertical Datum - A vertical datum is a surface of zero elevation to which heights of various points are referenced. The NVGD of 1929 was utilized until it was superceded in 1992 to be replaced with the North American Vertical Datum of 1988 for the contiguous US and Alaska.

NPDES: The National Pollutant Discharge Elimination System permit program addresses water pollution by regulating point sources that discharge pollutants to waters of the United States. Hydropower projects often have NPDES permits for non-generation discharges from cooling water and industrial wastewater systems.

Nutrient Loading: The amount of nutrients entering a system in a period of time. The overloading of nutrients in a system leads to eutrophication, causing excessive growth of algae.

O

Ogee: A double curve shaped like an elongated S, usually associated with a spillway configuration designed with optimal overflow characteristics.

Outlet: 为了特定目的，水可以通过一个开口从水库自由排入河流。

Outlet Gate: 控制水库出口水流量的闸门。

Overflow Dam: 设计为可溢流的大坝。

Oxbow: An oxbow wetland is a meander of a stream, river or creek, that has become separated from the flow of water. Oxbow wetlands store excess water that might otherwise lead to flooding, filter water to improve water quality and provide habitat to a variety of wildlife.

P

PCBs: Polychlorinated Biphenyls are a group of man-made organic chemicals consisting of carbon, hydrogen and chlorine atoms. PCBs do not readily break down once in the environment. They can remain for long periods cycling between air, water, and soil. They are also taken up into the bodies of small organisms and fish. As a result, people who ingest fish may be exposed to PCBs that have bioaccumulated in the fish they are ingesting.

Peaking: A peaking project is one in which water can be stored in a reservoir until needed, and then released through turbines to generate power to help supply the peakload demand.

Pelton Turbine: The Pelton turbine is an impulse turbine, which means that it generally uses the velocity of the water to move the runner. The water stream hits each bucket on the runner. There is no suction on the down side of the turbine, and the water flows out the bottom of the turbine housing after hitting the runner. An impulse turbine is generally suitable for high head, low flow applications.

Penstock: 一种封闭的管道状结构，将水从水库前池直接输送到发电站。

Plunge Pool: 天然或人工建造的水池，用于消散自由落体水的能量。

Point Source: Any single identifiable source of pollution from which pollutants are discharged, such as a pipe, ditch, ship or factory smokestack.

Polycyclic Aromatic Hydrocarbons: Polycyclic aromatic hydrocarbons (PAHs) are a group of over 100 different chemicals that are formed during the incomplete burning of coal, oil and gas, garbage, or other organic substances like tobacco or charbroiled meat.

Potamodromous: Potamodromous fishes move and complete their life cycle entirely within freshwater.

Powerhouse: A structure that contains turbines, generators, and associated equipment for the production of electrical power.

Primary Contact Recreation: Recreational activities in which quantities of water may be ingested. Examples include swimming, surfing, etc.

Programmable Logic Controller: A PLC (programmable logic controller) is a digital computer used for industrial automation to automate different electro-mechanical processes. At hydropower plants, PLC are often used to monitor and control key functions such as impoundment levels, minimum flow releases, turbine operation, and gate operation.

Propeller Turbine: A type of reaction turbine (generates power from the combined forces of pressure and moving water). Propeller turbines generally have a runner with three to six blades. Water contacts all of the blades constantly with constant pressure. The pitch of the blades may be fixed or adjustable. The major components besides the runner are a scroll case, wicket gates, and a draft tube. There are several different types of propeller turbines including Kaplan, bulb, straflo and tube.

PURPA: Public Utility Regulatory Policies Act of 1978, enacted following the energy crisis of the 1970s to encour­age cogeneration and renewable resources and promote competi­tion for electric generation. The statute imposes mandatory purchase obligations on electric utilities for power generated by cogeneration facilities and small power production facilities called "qualifying facilities."

R

Radial Flow Turbine: A type of turbine in which the water flows perpendicular to the shaft.

Radial Gate: A gate with a curved upstream plate and radial arms hinged to piers or other supporting structure.

REC: A renewable energy credit is a market-based instrument that represents the property rights to the environmental, social and other non-power attributes of renewable electricity generation.

Regulating Dam: A dam impounding a reservoir from which water is released in a controlled manner to regulate inflow that is then discharged downstream.

Reservoir: A body of water impounded by a dam and in which water can be stored. Typically used in reference to store-and-release facilities.

Riffle: Riffles are the shallower, faster moving sections of a stream or river.

Riparian: Riparian zones are the areas of land bordering streams and rivers, forming the transition area between aquatic and terrestrial systems. When riparian areas are intact and filled with trees, shrubs, grasses, and/or other vegetation, they act as buffers, protecting the river from the adverse effects of adjacent and nearby land use. Healthy riparian zones can capture and filter sediment, excess nutrients, and pollution from surface runoff. They can provide temperature regulation through shading to keep water cool. Plant roots hold the sponge-like soils in place providing bank stability and preventing erosion, and those soils can soak up and store excess water to reduce flooding during high flows and then release it slowly during periods of low flow. Riparian zones also offer habitat for a diverse community of plants and animals and provide critical inputs for the aquatic food web in the form of leaves, and other organic materials that drop from the vegetation into the water.

River Basin: The area drained by a river and all of its tributaries. Also referred to as the drainage area.

Rock Fill Dam: An embankment dam in which more than 50% of the total volume is comprised of compacted or dumped cobbles, boulders, rock fragments, or quarried rock generally larger than 3-inch size.

Roller Compacted Concrete Dam: A concrete gravity dam constructed by the use of a dry mix concrete transported by conventional construction equipment and compacted by rolling, usually with vibratory rollers.

Roller Gate: A dam gate designed to control flow through large waterway openings. They may be designed as either upward or downward (skimmer) opening. A roller or fixed wheel gate consists of a fabricated steel slide with cast iron rollers and rubber seals.

Rubber Dam: 固定在水坝顶部的充气结构，用于管理蓄水水位。

Rubble Dam: 砌石坝，其中的石块未成形或无层次。

Rule Curve: A mathematical curve or family of curves indicating how a reservoir is to be operated under specific conditions to obtain best or predetermined results. Rule curves can be designated to regulate water storage for flood control, hydropower production, and other operating objectives, as well as combinations of objectives.

Run of River: 一种水电运行模式，其中项目的流出量与水库的流入量以瞬时、每小时或其他时间为基础相匹配。

Runner: 涡轮机的旋转部分，将落水的能量转化为机械能。旋转轴与发电机相连。

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Saddle Dam: 建在水库边缘鞍座或低点上的任何类型的副坝。

Secondary Contact Recreation: 与水的接触仅限于四肢，不得摄入水。划船、钓鱼等。

Section 106: Section 106 of the National Historic Preservation Act of 1966 requires federal agencies to consider the effects on historic properties of projects they carry out, assist, fund, permit, license, or approve throughout the country. If a federal or federally-assisted project has the potential to affect historic properties, a Section 106 review will take place.

Siphon: 在道路、排水渠、河流等地下输送水的倒置封闭管道结构。

Slab and Buttress: 钢筋混凝土支撑结构通过单独的支撑基础将水负荷转移到地基岩石，利用蓄水的重量和结构的重量来抵抗滑动和倾覆。

Slide Gate: A hydraulic gate that operates in vertical guides and has no wheels, rollers, or other friction-reducing devices. Normally, such a gate must be opened or closed under balanced head conditions.

Sluice: An opening for releasing water from below the static head elevation of an impoundment. Usually equipped with a gate to control the flow and sometimes used for downstream fish passage. Can also be used like a skimmer gate to move debris downstream.

Spillway: A structure over or through which flow is discharged from a reservoir. If the rate of flow is controlled by mechanical means, such as gates, it is considered a controlled spillway. If the geometry of the spillway is the only control, it is considered an uncontrolled spillway.

Stanchion: A structure composed of vertical support bars or frames typically made of steel or concrete. A stanchion may be part of gate system and houses the mechanisms used to raise or lower a gate. A stanchion bay is a spillway section in which the frame creates a slot to hold stop logs or flashboards used to retain water in an impoundment. When stanchions are triggered by high flows and the logs or boards are released, flows discharge rapidly. In some cases, the logs or boards cannot be replaced until the impoundment level recedes below the elevation of the bay.

Stave: A narrow length of wood with a slightly bevelled edge to form the sides of barrels, tanks, tubs, vats and pipelines. In hydropower, wood stave pipelines or penstocks convey water from a dam to a powerhouse located at a distance.

Stilling Basin (or Pool): A basin constructed to dissipate the energy of rapidly flowing water, e.g., from a spillway or outlet, and to protect the riverbed from erosion or to support fish habitat below a dam.

Stop Logs: Large logs, timbers, or steel beams placed on top of each other with their ends held in guides on each side of a channel or conduit so as to provide a cheaper or more easily handled means of temporary closure than a bulkhead gate.

Substation:  A high-voltage electric system facility. It is used to switch generators, equipment, and circuits or lines in and out of a system. It also is used to change AC voltages from one level to another, and/or change alternating current to direct current or direct current to alternating current.

Substructure: The lower part of a building which is constructed below the ground level. The function of substructure is the transfer of loads from the superstructure to the underlying soil.

Surge Tank: A hydraulic structure designed to control pressure and flow fluctuations in a penstock or tunnel. It functions as a reservoir that temporarily stores or releases water to the turbine.

Switchyard: A concentration of electrical equipment which connects two or more electric circuits through switches, selectively arranged in order to permit a circuit to be disconnected or to change the electric connection between the circuits. In a hydroelectric project, the switchyard is the point at which the energy generated at the project is connected to the transmission or distribution system.

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Tailrace: The river channel into which water is discharged after passing through the outlet works or turbines.

Tainter Gate: A gate with a curved upstream plate and radial arms hinged to piers or other supporting structure.

Timber Crib: A dam constructed of timber cells filled with rock ballast and covered with sheathing on the water side to minimize leakage.

Timber Crib Dam: A gravity dam built up of boxes, crossed timbers or gabions (cages), filled with earth or rock.

TMDL: Total Maximum Daily Load - The calculation of the maximum amount of a pollutant allowed to enter a waterbody so that the waterbody will meet and continue to meet water quality standards for that particular pollutant.

Toe Drain: A system of pipe and/or pervious material along the downstream toe of a dam used to collect seepage from the foundation and embankment and convey it to a free outlet.

Transformer: 用于改变交流电电压的电磁装置。

Trap and Haul (or Trap and Truck): At dams and places where it is not practical to install a fish ladder, a trap and haul operation can be used to move fish upstream of a dam. Fish are attracted to flow provided at the base of a fish ladder. They climb the ladder to a loading system where they wait in pools or tanks before transfer into specialized tankers or barges. These vehicles release the fish into the river on the other side of the dam.

Trashrack: 安装在进水口处的平行杆架或屏风，用于防止碎片进入运河或涡轮机。

Turbidity: 由于悬浮沉积物而使水变得浑浊的程度。

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Water Classification: Categories of waters defined by states or tribes in their water quality standards that are based on the water's suitability for different uses such as irrigation, recreation, aquatic habitat, drinking water, or industrial, or other human uses.

Wetland: Lands including swamps. marshes, bogs, and similar areas such as wet meadows, river overflows, mud flats, and natural ponds. An area characterized by periodic inundation or saturation, hydric soils, and vegetation adapted for life in saturated soil conditions.

White Nose Syndrome: White-nose syndrome (WNS) is the fungal disease killing bats in North America. Research indicates the fungus that causes WNS, Pseudogymnoascus destructans, is likely exotic, introduced from Europe. WNS causes high death rates and fast population declines in the species affected by it, and scientists predict some regional extinction of bat species.

Wicket Gates: 可调节叶片控制流向涡轮机的水流量。

Wild and Scenic River: The National Wild and Scenic Rivers System was created by Congress in 1968 to preserve certain rivers with outstanding natural, cultural, and recreational values in a free-flowing condition for the enjoyment of present and future generations.

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303(d) Impaired Water Listing: The term is short for a state’s list of impaired and threatened waters (e.g. stream/river segments, lakes). States are required to submit their list for EPA approval every two years. For each water on the list, the state identifies the pollutant causing the impairment, when known. States often submit an "integrated report" that includes section 305(b) water quality reports for all state waters.

4(d) Rule: Section 4(d) of the federal Endangered Species Act (ESA) directs the US Fish and Wildlife Service to issue regulations deemed “necessary and advisable to provide for the conservation of threatened species.” It allows the Service to promulgate special rules for species listed as threatened (not endangered) that provide flexibility in implementing the ESA. 4(d) rules are used to target the take prohibitions to those that provide conservation benefits for the species. This targeted approach can reduce ESA conflicts by allowing some activities that do not harm the species to continue, while focusing the Service's efforts on the threats that make a difference to the species’ recovery.