黑鷹水壩 Black Eagle Dam 正確來說是黑鷲水壩 eagle 不能譯作鷹，只可譯作鷲或鵰，位於蒙大拿州，大瀑布城，座落於密蘇里河，是一座用於水力發電的重力壩 Black Eagle Falls Black Eagle Dam is the only one in the city See Great Falls Scores a Number of Firsts in Montana Great Falls Tribune March 20 2005 。第一大壩在 1890 年建成並開放，是一座土石壩 Peterson p 59 。黑鷹水壩是蒙大拿州第一座使用此結構的水力發電壩 Marcosson p 145 Holmes Dailey and Walter p 397，也是第一座建造在密蘇里河的水壩。水壩使大瀑布城獲得了電力城的封號 Citys Past Rooted in the River That Runs Through It Great Falls Tribune March 24 2002。第二大壩於 1926 年開工，1927 年啟用，使用混凝土建成。第二大壩在不拆除第一大壩的情況下淹沒並取代它。自 1926 年以來，水壩為長，高，幾乎沒有改變 PPL Montana Form S4 p A23，其發電廠有三臺渦輪機，每臺能產生 7 兆瓦的能量。最大輸出達 18 兆瓦。第二大壩為蒙大拿電力公司建造，賓州電力（PPL）公司在 1997 年買下並在 2014 年賣給西北公司。水庫沒有正式的名字，多年來被稱作長池（Long Pool）Peterson p 116。水庫大約 長 Peterson p 82，蓄水量從 Black Eagle Dam PPL Montana 2011 Accessed 20110405 到 The FERC order issuing a new license dated September 27 2000 states that the Black Eagle reservoir has a storage capacity of 1820 AF at normal maximum water surface elevation of 3290 feet See Water Right Solutions Inc p 4 。黑鷹水壩的發電方式是川流式發電 ，也就是它不刻意儲存水源來產生電力。 黑鷹瀑布 黑鷹瀑布是美國蒙大拿州密蘇裡河大瀑布中的第一個瀑布。在蓋水壩之前，此瀑布高低差就有 Cutright and Johnsgard p 26。 黑鷹瀑布形成於大瀑布構造區中，一條不平穩的下降沿上 Botkin p 255。密蘇里河在此流經古代沉積在河流、冰川與湖泊下，大部分為非海砂岩組成的庫圖納哈組 Fisher p 162，少部分是從淺海堆積而成 See generally Farshori and Hopkins 1989 Haney and Schwartz 2003。河流侵蝕較軟的砂岩，剩下的硬巖便自然形成了瀑布。 曼丹族和南派崗黑腳族等美國原住民都知道黑鷹瀑布 Robbins 2008 p 165 Howard p 1617 Federal Writers Project p 353。1805 年 6 月 13 日，路易斯和克拉克遠征隊的梅里韋瑟路易斯成為了第一位看到大瀑布的白人（五個瀑布中最大的）。第二天，探險隊在瀑布群附近露營時， 梅里韋瑟路易斯發現了黑鷹瀑布。 探險隊中某個成員稱瀑布為高音（Upper Pitch）Cutright p 156Howard p 66。路易斯看到後稱其為黑鷹 Vaughn p 83。1872 年，一位設計北太平洋鐵路的定線工程師，托馬斯P羅伯茨，在得知記錄在路易斯日誌的事件後，正式命名此瀑布為《黑鷹瀑布》Peterson p 20。 1890 年的大壩 大瀑布城水電公司（GFWPTC）成立於 1887 年 The Montana Almanac p 381，目標是發展大瀑布城，提供電力、自來水與汙水的處理，以吸引工商業進入城市。鐵路巨頭詹姆士希爾集合大北鐵路的主要股東，5 百萬美元資本。 希爾把股票賣給他的朋友，菲利普丹福斯阿莫爾，查爾斯亞瑟布羅德沃特，馬歇爾菲爾德，約翰穆雷福布斯，丹尼爾威利斯詹姆斯，約翰斯圖爾特肯尼迪，倫納德劉易斯和查爾斯埃利奧特珀金斯 Martin p xxi。巴黎吉布森是希爾的朋友，大瀑布城水電公司的股東之一，也是大瀑布城成立的推手 Malone 1996 p 132 Guthrie p 20 Taliaferro p 120121。吉布森意識到，密蘇裡河的大瀑布可以為工業提供豐富，便宜的電力，並在此基礎上推動城鎮發展 Taliaferro p 121。但吉布森的計劃意味著實際上要建設一個或更多水壩來提供想像中的電力。公司立刻開始購買密蘇裡河沿岸的土地和水利權，從黑鷹瀑布一路買到綿羊溪，約。到最後，公司幾乎擁有了大瀑布城的所有土地，加上河岸邊的地產。公司僱傭一位水利工程師 JT Fanning，在 1887 年夏天調查黑鷹瀑布，以確定瀑布的適宜性和大壩的最佳位置。當時計劃已完成，但沒有采取任何行動。 黑鷹水壩當時是為了供電給銅冶煉廠。在 1887 年 7 月 22 日，波士頓與蒙大拿銅銀綜合礦業公司創立，它是由倫納德路易森的路易森兄弟（一間銅貿易公司），蒙大拿公司（一間礦業控股公司）與 C X Larrabee （擁有高產量的礦場，Larrabee 和有名的山中礦）合併而成 A Montana Mining Deal New York Times July 23 1887 Death of Leonard Lewisohn New York Times March 6 1902 。 1889 年 9 月 12 日，波士頓和蒙大拿州與 GFWPTC 簽署了一項協議，其中電力公司同意在 1890 年 9 月 1 日之前建造一座能夠為該礦業公司提供至少電力的水壩，並在 1891 年 1 月 1 日前達到 Hyde p 86。作為交換，波士頓與蒙大拿銅銀綜合礦業公司同意在大壩附近建立一個 30 萬美元的銅冶煉廠。 1890 年黑鷹水壩開始施工 Peterson p 60，GFWPTC 的工程師設計一個由厚重木材定型，裡面充滿岩石的溢流壩。這個壩並不大，目的是在其後面建造一個蓄水池，以產生足夠的水壓（揚程）推動渦輪機發電。這水壩建造在上游邊緣（盡可能創造最深的水庫）Great Falls Mont p 249，花費約 515000 美元 Report of the Chief of Engineers Part II 1892 p 1906Another report claims the cost was only 275000 but that may be for just the cost of labor and not materials and the associated powerhouses See Great Falls Mont p 240（通貨膨脹至 2010 年約 12335000 美元 Great Falls Mont p 249）。1890 年 2 月 5 日工程開始投標，標案要求工程要在 1890 年 12 月 1 日前完成。所有投標都被拒絕，機械工程師莫里斯帕克被僱來設計與建造大壩 Parker p 59，為了把河流從工作區域轉移開，1890 年 4 月 15 日開始建造了圍堰壩 Parker p 64。在工地北邊的岸上蓋了名叫河岸（River Bank）的棚戶區，提供給幫助建造大壩的克羅埃西亞人、斯堪地那維亞人、斯洛伐克人與威爾士人（其中絕大多數人幫助找到了黑鷹鎮，還能看到當時土製的棚戶地基）。紅砂岩的河床盡可能弄平整，大塊的木材用螺栓固定到岩石上，與河流垂直。每兩塊木材間距，中間有六塊小木材，組成深的水壩 Parker p 6162，水壩的下游面間隔為 105 塊／公尺，Parker p 61 頂部間隔 108 塊／公尺，延伸了。水壩南端建立一個 的石牆以保護發電廠，防止水壩向廠房的壓力。水壩頂部每 建造一個寬的混凝土疏洪道，共八條 Parker p 62。在壩頂加裝一條高的檔板以增加蓄水量 Geological Survey p 26。水壩高，寬。 水壩在 1890 年 12 月開始發電 Peterson p 86。1891 年 1 月 6 日，水可流過水壩的頂部，1891 年 3 月 15 日，宣佈水壩完工。 河的南邊建了一棟佔地，磚瓦蓋的發電廠。內部有三臺雙組橫流維克託式水輪機，每臺能夠產生 127 兆瓦的能量 Parker p 65。南岸和離岸一段距離的石牆間產生一個供給鋼管河水的調整池，水流入鋼管的量一部分由調整池上游的閘門控制 Great Falls Montana p 350。主要的鋼管長，直徑，提供發電機水源（另有其他三條鋼管建成，但沒有立即投入使用）。 河的北邊是另一座在 1892 年建成的發電廠，裡面有七八組維克託水輪機，共產生 1940 兆瓦的能量，從河北岸底部切割出來的石塊堆積在附近形成一座小島：水渠島（Tailrace Island），而發電廠就蓋在這座人造島上 Talwani Sanjay Race Is On at Tailrace Island Great Falls Tribune May 7 1999。島嶼與密蘇裡河的北岸間形成了黑鷹水壩的水渠（也是發電廠的水渠）。水渠島由電力公司與波士頓蒙大拿礦業公司共同擁有。電廠與冶煉廠由一座木製天橋連線起來。北岸與石強形成筆直的調整池供應北邊的發電廠（最寬的部分有） 水的流量與南邊一樣，由閘門控制。三條鋼管供給北邊發電廠水源 Parker p 66。然而，此發電廠產生的機械能大部分並沒有轉成電能，而是透過繩索與滑輪系統直接轉移到冶煉廠 Hebgen p 1539。 兩間電廠產生的部分機械能，透過湯姆遜 休斯頓發電機轉換成電力，單一員工在電廠裡工作八小時。次要的發電廠蓋在南邊發電廠隔壁，裡面裝載一臺 Armington Sims 蒸汽發電機，在主發電機關閉時，供應客戶電力。長的纜索鐵道（傾斜的鐵路）接通懸崖上面與南邊發電廠。懸崖上有多條長， 寬的吊橋跨越河上連線各個發電廠。水壩預估可用 50 年。 1890 年水壩運作歷史 1890 年春天，冶煉廠開始動工；1891 年 3 月，選礦機啟用 A concentrator is a mechanical device which separates ore from dirt debris and tailings；1892 年 4 月，Brückner cylindersA Brückner cylinder is a rotating bricklined horizontal metal cylinder which heats ore burning off undesirable chemicals such as sulphur 與反射爐啟用；1892 年 8 月，蒸餾轉換器啟用；1893 年 1 月，精煉爐啟用 A refining furnace melts the metal into a liquid Undesirable material or dross usually floats to the top allowing it to be removed；1893 年 2 月，電解精煉爐啟用；1893 年 4 月，高爐啟用 Mutschler p 13。冶煉廠起初預算為 200 萬美元 Raymer p 18，在 1892 年員工數已達 1000 位。1908 年 4 月 7 日，大煙囪（Big Stack）開始建造，底部內徑，頂部，將廢氣排到的高空。由紐約的 Alphonse Custodis 建築公司於 1908 年 10 月 23 日完工，成為當時最高的煙囪 Marcosson p 289。 18931894 年，GFWPTC 在現有的南岸發電廠下游，建造了第二個發電廠，將電力輸送至懸崖上的皇家研磨公司的麵粉研磨廠。1897 年，又在北岸旁建造另一個發電廠以提供冶煉廠更多電力。 1908 年 4 月 14 日，下午 230 左右，大瀑布上游 90 英里處的豪瑟水壩潰堤 Hall Montana 1912 p 135 Jackson Dams 1997 p 6566 Wegmann The Design and Construction of Dams 1918 p 298 Terzaghi Peck and Mesri Soil Mechanics in Engineering Practice 1996 p 478，高到的浪潮襲捲下游 Dam Bursts in Montana New York Times April 15 1908。大北鐵路指派一臺火車頭沿路警告住在通往大瀑布城的鐵路周邊居民 Smith 1908 p 237。礦業公司的工人簡易地搭建了一個翼壩，以從冶煉廠轉移洪水，並炸開了一部分的黑鷹水壩以利洪水迅速流向下游 Peterson p 61Two Towns Swept By Montana Flood New York Times April 16 1908Ecke Richard Floods of 1908 Disaster Struck Great Falls 100 Years Ago Great Falls Tribune June 8 2008。但當河水到城市時，密蘇裡河只漲潮了 Axline Hauser Dam METNetMTgov no date。有兩名員工在爆破時身亡：一位在移除水壩的插板時溺死，另一位死於船隻翻覆。 同年的 6 月 6 日，黑鷹水壩遭受另一波洪水的攻勢。一天之內地區降雨量達 76 公分，密蘇裡河在八小時內漲潮將近 41 公分 Wilmot Paula Todays Great Falls Begins to Take Shape Great Falls Tribune January 31 1999。河水比洪水位高出（密蘇裡河的平均水位為），5 位居民被淹死。冶煉廠試圖在黑鷹水壩北邊利用 4 輛滿載的火車車廂阻擋朝向發電廠的洪水 。許多建築被沖走，在當時是大瀑布城最嚴重的水災。一些建築撞上了黑鷹水壩，一些超過水壩的部分掉到瀑布下，大壩上的行人吊橋也被沖毀（今日，可以在第六街地下道看到一個牌子標示高水位的範圍。）大壩本身也有些受損，之後便修復完成，通往水渠島的舊木橋也用沃倫桁架橋取代，可行駛汽車。現在島上甚至有停車場供員工停車 Wilmot Paula On the Rivers Edge Great Falls Tribune June 5 2001。 20 世紀前期，黑鷹水壩的所有權改變了兩次。1908 年，約翰D萊恩（比尤特的達利信託與阿納康達銅礦公司總裁，之後成為助理國務卿 Morris p 227 John D Ryan Dies Unexpectedly New York Times February 12 1933） 購買了 GFWPTC 絕大部分的股份。1910 年，GFWPTC 組織其子公司大瀑布電力公司，接管了黑鷹水壩及其他水力發電專案（當時正在建設）的所有權與經營權。1912 年發生了第二次所有權變更。霍爾特水壩的成本超支，投資者對水壩建設的熱情減弱，以及與豪瑟水壩潰堤的責任使聯合密蘇裡河電力公司的最大股東塞繆爾託馬斯豪瑟幾乎破產 Holter Hydroelectric Facility HAER No MT94AHAER MONT 25WOCRE1A Historic American Engineering Record National Park Service November 1994 p 2Clary Lewis Clark on the Upper Missouri 1999 p 137，使他必須售出聯合密蘇裡河電力公司給約翰D萊恩。1912 年 10 月 25 日，約翰D萊恩把兩間公司合併成比尤特電力公司、比靈斯與東蒙大拿電力公司與麥迪遜河電力公司，三間公司組成了蒙大拿電力公司 Aarstad et al p 125 Malone 2006 p 204 Goodsell and Wallace p 649 。同年，黑鷹水壩產生的功率（39 兆瓦至 57 兆瓦）輸往新的冶煉廠，而僅有 07 兆瓦的電力輸送到附近城市。另外有 300 馬力的機械能來自水車，並透過繩索與滑輪輸送往皇家麵粉廠。 1913 年，蒙大拿電力公司升級了黑鷹水壩的產電能力（而不是機械能）。公司放棄了原先規劃的南岸第二座發電廠，改裝載兩臺法蘭西斯水輪機。第一座發電廠的舊發電機汰換成兩臺可產生 15 兆瓦的新發電機 Big Power House Will Be Erected The Troy Tribune April 2 1926。廠內又造了兩座調壓艙，並連線壓力管。翻新後的南方發電廠現在直接提供電力給冶煉廠和磨坊而不是機械能了。 1926 年的水壩 1909 年，大瀑布電力公司的工程師提議在三個地點蓋水壩：彩虹瀑布（彩紅水壩，Rainbow Dam）、大瀑布（瑞安水壩，Ryan Dam）、密蘇裡河的峽谷（科克倫水壩，Cochrane Dam，位於前兩個水壩中間）。1914 年，蒙大拿電力公司打算加高黑鷹水壩來增加發電能力 Editorial Correspondence p 1113。1916 年，大部分的波士頓與蒙大拿冶煉廠被現代銅礦與鋅礦的冶煉廠取代，同時加設電線跟電纜的製造廠 Federal Writers Project p 150。雖然黑鷹水壩更新了渦輪機與發電機，它當時仍然只能產生 3 兆瓦的電力，而電力需求則一直提升。在 1920 年早期，黑鷹水壩已不足以提供大瀑布城的用電所需，再加上新的鋅冶煉廠需要 10 兆瓦的電力。1925 年，北邊發電廠被認為嚴重的過時。 1925 年末，蒙大拿電力公司計畫建設新的水壩與發電廠。查爾斯T馬恩（Charles T Main）的公司負責監督水壩的重建，蒙大拿的顧問工程師亨利柯克倫（Harry Cochrane）負責重新設計水壩，因此此水壩稱作科克倫水壩（Cochrane Dam）Talk of the Town Great Falls Tribune June 30 2003。1926 年 4 月 1 日，蒙大拿電力公司宣佈要花費 100 萬美元在黑鷹水壩建造新的發電廠。但隨著工作的進展，他們意識到水壩及其四座發電廠太舊，無法滿足發電需求。他們調整計畫，決定在水壩下游處新建一個水壩 Aarstad et al p 25。南邊的調整池被放棄，並保留北邊的調整池且好好地維修一番。1897 年蓋的北岸發電廠被拆除，在同一地點蓋了混凝土的新發電廠。他們記取 1908 年的教訓，廠房設計與位置皆有以此作為考量。 拆除南岸發電廠的同年夏天，開始了新建水壩的工程。工人替新水壩澆灌混凝土時，舊水壩用來當作圍堰。新水壩於 1927 年 8 月 1 日完工，完全淹沒了舊水壩，在 9 月開始發電。新水壩長，高，溢洪道長。它的高度受到上游城市的淡水和汙水設施限制，如果水壩更高，會淹沒設施 Peterson p 62。水壩頂部呈現 O 形，可以改善水流。新大壩有八個水閘，與一條帶欄杆的人行道，讓維護人員能夠到達閘門和水壩 Peterson p 63。 新發電廠由混凝土建成，不過公司曾計劃要建造成磚瓦屋，但當地磚匠要求獲得城市規定的工資，而不是蒙大拿州政府的，因後者薪資較低。廠房南邊和北邊的混凝土和石砌牆用於防止水流侵蝕調整池和水渠道。調整池長，寬，延伸至較下游的新動力室，舊動力室的磚拱門結合到了調整池的牆壁中。新發電廠搭載三臺由 S 摩根史密斯公司提供的垂直卡布蘭式水輪機，能夠產生 18 兆瓦能量，成為蒙大拿電力公司在大瀑布地區五座水壩中最大產能的一座。史密斯公司在渦輪機上加裝油壓調速器（調節每個渦輪機的速度）與導流管（在水離開渦輪機後速度被降下來，並使得從上快速落下的水持續向渦輪機的螺旋槳傳遞能量）。渦輪機螺旋狀入口和導葉門固定在發電廠的地下室，每臺渦輪機都安裝在自己的坑槽內。每臺渦輪機透過一樓的屋頂連線到額定功率為 7000 伏安的阿里斯－查爾默斯（AllisChalmers）發電機。直流發電機作為阿里斯－查爾默斯發電機的激勵器。六臺 6600 2200 伏變壓器降低了電壓供使用。 1926 年重建後，黑鷹水壩遭遇了四次洪水，但都沒有造成損害。第一次發生在 1953 年 6 月 4 日，春雨和融雪導緻密蘇裡河高於洪水位 Searl p 182，沒有大壩損毀的報告。第二次在 1964 年 6 月 10 日，洛磯山脈的大雨導緻密蘇裡河高於洪水位，比 1908 年的洪水高出。位於樺樹溪的 Swift Dam 潰堤，造成 19 人死亡 Parry p 125126，下雙麥迪遜湖水壩（Lower Two Medicine Lake Dam）也潰堤，造成 9 人死亡。儘管因大洪水造成 3000 人被迫離開家園，此次黑鷹大壩仍未受損。 （Mel Ruder 因洪水報導而被授予突發新聞報導普利策獎 Lawrence p 89）。1975 年 6 月 21 日發生第三次洪水，洛磯山脈 24 小時內降雨超過 National Climatic Center p June 197522。在太陽河升至（高於洪水位）後，超過 5000 人從大瀑布城撤離 5000 Persons Flee Montana Floods Associated Press June 22 1975。損失超過 1700 萬美元，的土地被淹沒。洪水幾乎淹沒了黑鷹大壩，但沒有對結構造成傷害 Peterson p 64。第四次大洪水在 1997 年 6 月 17 日 Peterson p 8，又多又快的融雪導緻密蘇裡河高於洪水位 Floods a Menace in Idaho Mont USA Today June 16 1997。黑鷹水壩還配備了一個緊急 trip face 可以解除水壩上所有插板，讓河水能夠以每秒鐘的水量流過。 長池水庫 黑鷹水壩在它後面建立了一個長約的水庫。緊鄰第一大壩的水庫大約深，容量 Ripley p 3361892 年測量長池的平均深度為。參見：Report of the Chief of Engineers Part I 1892 p 265。目前水壩的蓄水量為到。 這水庫沒有正式名稱，但由於水流緩慢猶如靜止，以及從上游的喀斯喀特到黑鷹瀑布的坡度低（沿著蜿蜒的密蘇裡河約長），這個水體一直被稱為「長池」。在 1872 年，命名黑鷹瀑布的託馬斯 P羅伯茨，正式命名這個水體 Roberts p 256257。美國陸軍工兵部隊於 1883 年和 1910 年使用過這名稱 Report of the Chief of Engineers 1883 p 1340 Annual Reports of the War Department for the Fiscal Year Ended June 30 1903 p 406 Annual Reports of the War Department for the Fiscal Year Ended June 30 1906 p 484 War Department Annual Reports p 645。在 1891 年至 1917 年就已經廣為流行 Sweetser and King p 513 Beach and McMurry p 1254，蒙大拿州議會也已在此時使用這名稱 Strahorn p 49。因此現代歷史學家也用這名稱提及它 Lass p 379 380，1949 年後被電力業出版物使用 Nichols p 329。現在，從第一林道北橋第一林道北橋在黑鷹水壩上游。到密蘇裡河與太陽河交匯處（距離約）為知名的布羅德沃特灣（知名人士如：查爾斯阿瑟布羅德沃特、蒙大拿鐵路執行長、房地產投資者和銀行家）Peterson p 77。 水壩開發 1926 年大壩重建後，工人和居民可以穿越大壩頂部上班或上學 Wilmot Paula The Big Stack Great Falls Tribune September 18 2002。出於安全原因，蒙大拿電力公司在二戰時期關閉了道路，並封閉到現今。 1950 年，根據《聯邦電力法》，蒙大拿電力公司被迫授權黑鷹水壩等大部分發電用水壩。聯邦電力法案於 1935 年透過，在 1937 年 12 月，聯邦電力委員會（FPC）開始執行一項程式（FPC Docket IT5840），賦予 1935 年之前建造的所有水壩許可證 Gatchell p 50。該法案賦予聯邦電力委員會在美國可航行水域中，所有水壩的控制權 Plum p 398。經過長時間的研究、資料收集以及談判之後，1946 年 11 月 18 日開始舉行聽證會，以確定蒙大拿電力公司在 1935 年之前修建水壩前，河流是否可通航以致水壩屬法律生效範圍 Smith 1951 p 316 。1947 年 9 月 30 日發布的第 170 號意見書中，審判員認為此河流可以通航，並且含黑鷹水壩等水壩應該獲得許可 Federal Power Commission p 678Navigability of Missouri Argued Associated Press February 17 1948。 蒙大拿電力公司在聯邦電力委員會於 1948 年 2 月 16 日舉行聽證會時訴願。當聯邦電力委員會駁回時，蒙大拿電力公司轉向哥倫比亞特區聯邦上訴法院上訴。1950 年 10 月 4 日，David L Bazelon 法官以 2 比 1 多數決判決「蒙大拿電力公司訴聯邦電力委員會案」Montana Power Co v Federal Power Commission 185 F2d 491 AppDCCir 1950 cert dend 340 US 947，指出「密蘇裡河從本頓堡到斯里福克斯長達 263 英里，屬美國通航水域，符合《聯邦電力法》的許可要求」Montana Power Co v Federal Power Commission 185 F2d 491 495。法院認為黑鷹、莫羅尼、彩虹、瑞安水壩都在通航水域，無權侵佔公有地 FPC is Upheld on Dam Licenses New York Times October 5 1950。豪瑟水壩在通航水域，並持有無效許可證佔用公共土地。霍爾特水壩擁有有效許可證，但該許可證沒有延伸到它使用的通航水域。赫布根和麥迪遜水壩在不通航水域，但沒有有效許可證而佔用公有地。上訴法院將 Canyon Ferry 水壩的問題退還給地方法院，因為該水壩已被出售給聯邦政府。蒙大納州電力公司向美國最高法院提出上訴， 美國最高法院於 1951 年 3 月否決了特許權（拒絕審理此案）United States Supreme Court New York Times March 13 1951。 蒙大拿電力公司隨後於 2000 年 9 月 27 日由聯邦能源管理委員會（FPC 的繼承機構）重新授權並贏得了黑鷹水壩營運許可，許可證編號為 P2188。另外還有 7 座需要法院裁決。Complete List of Issued Licenses Licensing Hydropower Federal Energy Regulatory Commission November 23 2010 Accessed 20110411 1978 年，修復三臺阿里斯－查爾默斯發電機，1982 年，再修復一次。1997 年，蒙大拿電力公司修復並重新粉刷了通往水渠島的橋。 1999 年 11 月 2 日，蒙大拿電力公司宣佈以 16 億美元的價格賣給賓州電力公司（PPL）所有水壩和發電廠 Johnson Charles S MPC to Sell Power Plants The Missoulian December 10 1997 Anez Bob PPL Global Buying Montana Power Plants for 16 Billion Associated Press November 2 1998 Kenworthy Tom In Montana a Volt Out of the Blue Washington Post March 4 1998。這筆包含黑鷹水壩的買賣估計會給蒙大拿州帶來 3000 萬美元的稅收 Black JoDee Rainbow Dam PPL to Flow 175 Million Into Upgrade Great Falls Tribune February 27 2008（但蒙大拿電力公司表示稅金會比 3000 萬少 MPC Casts Doubt on 30 Million Tax Payment on Dam Sales Associated Press March 3 1999）。2001 年 11 月，因電價上漲而不滿的民眾提出一項倡議：要求州政府收購 PPL 所有用來發電的水壩（包含黑鷹水壩）Gallagher Susan Drive to Buy Montana Hydroelectric Dams Announced Associated Press November 20 2001。在 2002 年 11 月，這項倡議被否決了 Berg Christian Montanans Reject Buying PPL Dams Allentown Morning Call November 7 2002。 在蒙大拿電力公司將黑鷹水壩賣給 PPL 的時候，蒙大拿電力公司正在安裝控制裝置，使黑鷹水壩能夠從彩虹水壩遠端操作。當時，PPL 表示他沒有計劃擴大黑鷹水壩的發電能力。同樣在 1999 年，蒙大拿電力公司將大部分的水渠島轉移到大瀑布市作為娛樂區 Wilmot Paula The Rebirth of Smelter Hill Great Falls Tribune June 21 1999。此外，蒙大拿電力公司和 ARCO（波士頓和蒙大拿州的後繼公司）在該島上鋪設了（46 公分）的表土，花費了 50 萬美元用於景觀設計，並增強了動力廠附近的安全邊界，並同意資助一部分小島的定期保養費用。 1990 年代後期，歷史學家史蒂芬安布羅斯建議拆除黑鷹水壩，將瀑布恢復原狀 The Edge Great Falls Tribune December 11 1999。 2010 年，黑鷹水壩的發電與輸電系統開始翻新。同年 6 月，PPL 蒙大拿州分公司花費 5500 萬美元用高壓電線取代該地區電力網路 PPL Planning 55 Million Transmission Upgrade Great Falls Tribune June 21 2010。新的電線取代了 80 多年前的裝置，電線間隔更大，使得大型鳥類可以安全地透過或棲息在電線上。PPL 也計畫更新電廠旁的變電所，兩項工程都預期會在 2012 年完工。 沉積物、水流量、殘骸、緊急狀況 密蘇裡河與支流夾帶的沉積物是黑鷹水壩的一大問題。太陽河（Sun river）在黑鷹大壩上游幾英里處與密蘇裡河相連，夾帶著汙泥，養份與藻類，因此還被諷刺成 浮渣河（Scum river）Sun River Cleanup Effort Has Done Much in Short Time Great Falls Tribune August 3 2000。 太陽河水呈現如巧克力牛奶的顏色，流入相對清澈的密蘇裡河後使其變得汙濁。汙泥降低水庫容量，充滿調整池，也會對發電機組造成損害。1988 年，由於密蘇裡河從太陽河到彩虹水壩一段的沉積物和懸浮物，蒙大拿州環境質量部（Montana Department of Environmental Quality MDEQ）根據 1972 年清淨水法第 303（d）節，將其水質狀態列入受損。黑鷹水壩因為減緩水流流速，被列為問題來源之一。為瞭解決這個問題，1994 年，7 個聯邦機構，8 個州政府機構，10 個蒙大拿州政府機構，4 個環境組織和幾個蒙大拿州地主共同努力減少進入太陽河及其主要支流（Muddy Creek 與 Careless Creek）的營養物和沉積物。約 623500 美元的清潔水法基金、200 萬美元的聯邦基金以及 250 萬美元的州與地方基金用於恢復河岸植被、改善河邊放牧、復原河床斜度和改善灌溉方法。到 2010 年，Muddy Creek 減少 75 沉積物，Careless Creek 減少 25Montana Section 319 Success Stories Vol III Office of Water US Environmental Protection Agency October 13 2010 Accessed 20110409。 黑鷹瀑布是否流通，取決於黑鷹水壩。每年 5 月，理論上密蘇裡河的中位水流量為每秒 Lee Sonja Falls Wont Be So Great Great Falls Tribune May 25 2001。2000 年 10 月，水壩水位下降，瀑布停止流水四週，PPL 蒙大拿在這段時間修整了調整池，閘門和鋼管濾網 PPL to Work On Black Eagle Dam Great Falls Tribune October 26 2000。PPL 蒙大拿的工作許可證要求水壩在週末與亡兵紀念日至勞動節期間的上午 9 點至下午 8 點流出至少每秒的水量。如果水位或發電需求允許，水量可能更多。2001 年 5 月，PPL 蒙大拿表示因為水流量只有平時的 40，他們要在 7 月 4 日後截斷瀑布 Not Much Waterfall Action Likely in Great Falls This Summer Associated Press May 26 2001PPLs Request to Shut Down Dams This Summer Approved by FERC Great Falls Tribune June 2 2001。2004 年 9 月，水庫水位再次降低，以修復檔板 Black JoDee PPL Lowers River to Improve Dam Great Falls Tribune September 18 2004，河流缺水使巨人泉附近的密蘇裡河天然通道暴露出來。2008 年 67 月，水庫水位又過低以致瀑布再次停流，而在一次大雨後移除了檔板使水流快速透過 Replacement of Flashboards Creates Temporary Mud Flats on the Missouri near Black Eagle Dam Great Falls Tribune July 2 2008。當水流透過並把檔板歸位後，水庫內剩沒多少水，而瀑布再次流通也是幾天後的事了。 因為黑鷹水壩屬於溢流壩，所以漂流的殘骸很容易阻塞進水口。常見的阻塞物有浮木與原木，但有時連船塢、保齡球、划艇、浴缸、木棚與鋼棚也會卡在水壩上。Schulz Kathleen Bob Bound for New Orleans Great Falls Tribune March 27 2004 Removing hollow items can be dangerous because the water pressure against them can cause them to implode In addition to large amounts of driftwood about 100 animal carcasses cattle deer dogs and various small animals become lodged against the dam or the penstock intake screens each year Floating screens at the entrance to the forebay catch many items as do the penstock intake screensHall Ryan Hundreds Tour Black Eagle Dam Great Falls Tribune August 30 2009 Workers use a crane to remove items from these screens and bury the items retrieved at a landfill Dam operators also use a yellow civilian version of the Alvis Stalwart amphibious vehicle to remove objects and to maintain the damPPL Montana Holding Open House Great Falls Tribune August 26 2009 This vehicle caused a stir in Great Falls in June 2006 when local residents driving on a nearby road mistook the vehicle for a sport utility vehicle which had fallen into the waterAmphibious Vehicle in River Causes Stir Great Falls Tribune June 24 2006 Ice is another form of dangerous debris for the dam In December 2010 blocks of floating ice overwhelmed the top of the dam tearing the handrails off the maintenance walkwayEvaro Donna Missouri River Ice Jam Being Watched Closely Great Falls Tribune December 23 2010 For many years Black Eagle Dams owners were required to hold simulations every five years to plan for various kinds of emergencies flood sabotage mechanical breakdown etc which might affect the dam and public safetyAdcock Clifton Are We Prepared Great Falls Tribune January 16 2006 After the September 11 attacks these exercises were required to happen every year PPL Montana works with local and state government and law enforcement other companies and the news media to plan for various contingencies and improve how it might respond in a disaster or emergency Tax dispute and Supreme Court riverbed case Taxation of the dam has been an issue of contention since 2000 During the 2002 ballot initiative fight PPL Montana said its dams were worth at least 767 millionMontanans Reject Buying PPL Dams Allentown Morning Call November 7 2002 But in 2003 PPL argued that the dams were worth much less PPL Montana challenged the amount of property taxes assessed on Black Eagle and its four other dams in the area protesting 1087 percent of the 448 million 2000 tax assessment 65 percent of the 48 million 2001 tax assessment and 8565 percent of the 496 million tax assessmentProperty Taxes Paid By Private Electricity Generating Plants and Dams in Montana Great Falls Tribune January 26 2003 This amounted to 30 percent of its total property tax assessment in the state of Montanawith onethird of amount owed payable solely in Cascade County In February 2005 the Montana State Tax Appeal Board gave the state a partial victory reducing the states assessments by 10 percent but otherwise upholding the assessment methodDennison Mike State Wins PPL Tax Appeal Great Falls Tribune February 12 2005 Johnson Charles S Revenue Dept Still Assessing Impact of Ruling Billings Gazette February 15 2005 However the tax board did not address PPL Montanas primary claim that the state was assessing its plants differently solely because they were unregulated PPL Montana appealed the ruling to the Montana Supreme Court in 2007 On December 4 2007 the Montana Supreme Court unanimously ruled in State Dept of Revenue v PPL Montana that the tax appeal board had properly assessed PPL Montanas dams However PPL Montana had continued to dispute its tax assessments from 2003 to 2007 and the ruling did not directly address those challenges But on December 14 2007 PPL Montana offered to pay its 2003to2007 tax assessments at the slightly lower rate established by the tax appeal board Another tax issue arose in 2007 The parents of several Montana schoolchildren filed suit in the United States District Court for the District of Montana against PPL Montana The parents argued that all riverbeds in Montana are owned by the state are held in trust for the benefit of all the people and that such riverbeds constitute a portion of state lands which must be taxed or leased to provide support for public schools The plaintiffs argued that PPL Montana and its predecessor Montana Power only leased these riverbeds from the state and did not own them The parents sued to force PPL to pay rent due At no time in the past had the state sought rental income from Montana Power and no payments by Montana Power or PPL Montana had ever been made Although the federal suit was dismissed for lack of a federal issue PPL Montana filed suit in Montanas First Judicial District Court seeking a declaratory judgment in its favor arguing that the Federal Power Act preempts the parents suit and denies states the power to make companies pay for the use of riverbeds The state district court held against PPLs request for summary judgment on all counts The two parties then went to trial which lasted from October 22 to October 30 2007 On June 13 2008 the state district court ruled in favor of the state although it denied the states request for interest on the rent due PPL Montana appealed to the Montana State Supreme Court On March 30 2010 the Montana State Supreme Court held 5to2 that the state district court had not erred in its rulings on various issues of summary judgment that riverbeds were state public trust lands but not school trust lands under the Montana Constitution and that the district courts calculation of payments due was appropriate PPL Montana appealed to the Supreme Court of the United States and in November 2010 the Supreme Court asked the United States Solicitor General for the views of the federal government Finally on February 22 2012 the US Supreme Court held in PPL Montana v Montana No 10218 dec February 22 2012 that the Montana Supreme Court had erred in finding all of the riverbeds beneath all PPL Montana dams navigable The unanimous US Supreme Court held that the correct test is whether the portion of the riverbed under each specific dam not the entire river nor even a large or small portion of a river was navigable at the time of statehood If it was then the riverbed is navigable and may be taxed The case was remanded back to the state supreme court for further hearingsDennison Mike US Supreme Court Overturns Montana Courts on PPL Riverbed Rent Billings Gazette February 23 2012 Flashboards on the dam were slightly damaged during flooding in the spring and early summer of 2011 Water behind the dam was lowered until it barely crested the dam so repair crews could replace the flashboardsMissouri River Lowered for Maintenance to Black Eagle Dam KFBBTV July 19 2011 Accessed 20110930 Recreational aspects and fishery management Fishing and water quality issues The river above and below Black Eagle Dam is used for fishing Westslope cutthroat trout were first identified at Black Eagle Falls by Lewis and Clark in 1805 and the fish still are plentiful in the areaBehnke and Tomelleri p 139 Rainbow trout are also plentiful upstream from the damEvaro Donna FWP Seeks Comments on Fishing Regulations for Season Starting in March Great Falls Tribune August 12 2010 The area below Black Eagle Falls has been rated by one guide as a good area for fly fishing smallmouth bass and walleyeRobbins 2005 p 323 For many years the state of Montana managed the Long Pool reservoir as part of one fishing management area and the river below the dam as part of anotherBabcock Michael Missouri Fisheries Plan Is Out Great Falls Tribune September 23 1999 This was changed in 1999 so that the two are now managed together The change also instituted a new limit on trout caught and killed below the dam of five fish per day only one of which could be over Limits on the number of walleye caught per day were lifted in 2010 to protect the rainbow and brown trout populations they had been five daily and 10 in possessionBabcock Michael Anglers Disagree Over Proposed New Fishing Regs Great Falls Tribune September 2 2010 According to dam officials there are no screens to prevent fish from going over the dam or through the penstocks and turbines Fish go right through the turbines it doesnt seem to bother them dam operators say Since 1988 the Long Pool and the Missouri River in and around the city of Great Falls have been listed as an impaired waterway under the 1972 Clean Water Act This area was first listed as impaired due to sedimentation siltation and suspended solids in 1988 High levels of chromium mercury and selenium were listed as impairing factors in 1992 High turbidity haziness of water due to suspended particles was added as an impairing factor in 2000 Sources of these impairments include Black Eagle Dam upstream abandoned mines irrigation runoff industrial sources and stormwater runoff The MDEQ has given the area a quality ranking of B2 fourth out of 18 declaring it suitable for human consumption and recreation after treatment but only marginal for salmonid fish other aquatic animals waterfowl and furbearing animals MDEQ has scheduled the Long Pool and Missouri River watershed in this area for future improvement In 2011 the former smelter next to Black Eagle Dam was listed by the United States Environmental Protection Agency EPA as a Superfund hazardous and toxic waste sitePuckett Karl EPA Adds Black Eagle Site to Superfund List Great Falls Tribune March 9 2011 The EPA also said it would begin sampling for the riverbed above and below Black Eagle Dam as well as residential areas in the town of Black Eagle for heavy metals contamination Historic records show that plant wastes were routinely dumped into the Missouri River below Black Eagle damEnvironmental Protection Agency EPA Adds Anaconda Copper Mining Co Smelter and Refinery in Cascade County to Superfund Site List Press release March 8 2011 MDEQ estimated in 2002 that between and of waste were dumped into the river between 1892 and 1915 EPA samples indicated that the contamination could extend as far downstream as Fort Benton away Toxins present in the water and riverbed according to the EPA include antimony arsenic cadmium chromium cobalt copper iron lead manganese mercury nickel silver sodium and zinc Wildlife and hunting The area around the falls despite its urban setting is a habitat for many animal and bird species Among the birds commonly found in the area are bald eagles California gulls Canada geese cliff swallows eared grebes egrets golden eagles American goldfinches gray catbirds house wrens ibises ospreys rednecked grebes sandhill cranes snow geese tundra swans turkey vultures western grebes western meadowlarks white pelicans and numerous species of duck owl and warblerRobbins 2008 p 165166 Crawford p 167 Tirrell and Reddy p 48 Common animal species in the area include beavers mule deer muskrats river otters and whitetailed deerRobbins 2008 p 166 Beavers are so common in the area that officials consider them pests and trees in city parks have had to be protected against themKotynski Tom Talk of the Town Great Falls Tribune June 7 1999 At one point beavers were chewing down two trees nightly on Black Eagle Memorial IslandEcke Richard Beavers Leave Their Mark Great Falls Tribune November 30 2010 These included two red oak trees found growing on the hill above the damthe only two red oak trees in northcentral Montana As of 2006 most of the north shore of the Missouri River below Black Eagle Dam was undeveloped as far down a Sulphur Spring a distance of aboutLee Sonja Cleanup Project Planned for Today Great Falls Tribune September 30 2006 Known as the Lewis and Clark Greenway this area is under a permanent conservation easement Although the area below Black Eagle Dam is open for bird hunting the reservoir and river upstream from Black Eagle Dam to Sand Coulee Creek is a nohunting areaBabcock Michael For Area Goose Hunters Great Falls Tribune January 13 2005 Wildlife hunting is also available on the north shore of the Missouri River from below Black Eagle Dam to Morony DamCheck Rules Before Heading Out to Hunt on State Lands Great Falls Tribune August 31 2006 Most of this land is owned by PPL Montana but there is some private land here which is not open to hunting The PPL Montana lands are open to hunting due to a conservation easement but the Montana Department of Fish Wildlife and Parks requires hunters to obtain a map of these lands before using them for hunting There are also restrictions on the type of weapons which may be used in this area and where hunters may park Recreation area improvements Black Eagle Dam is also utilized as a recreation area The whitewater just below the falls is a good place for canoeing innertube floating and kayakingFischer and Fischer p 129 Babcock Michael Where to Float Your Boat Great Falls Tribune June 5 2003 Harrison Elizabeth Outdoor Fun Begins With Indoor Kayak Class Great Falls Tribune January 31 2010 Hiking and bicycling also occur in the area Beginning in 2006 the Black Eagle Dam Run a runwalk and run has been held at Black Eagle Dam in midJulyRegional Briefs Great Falls Tribune July 8 2006 The annual Lewis and Clark Festival celebrated in late June the anniversary of the discovery of the Great Falls focuses on events held around Black Eagle and other dams on the Great Falls of the MissouriSorich Jake Luminaria Walk is Saturday Great Falls Tribune June 25 2010 In midJuly the Rivers Edge Trail Luminaria Walk occurs around Black Eagle Dam and the falls and are illuminated with colored spotlights during the event On May 5 1998 the United States Forest Service opened the Lewis and Clark Interpretive Center a 6 million museum and education center which includes an exhibit hall theater store and classrooms which tells the story of Lewis and Clarks passage through central Montana and their discovery of the Great Falls of the MissouriSkornogoski Kim LC Centers Sixth Birthday Great Falls Tribune May 3 2004 Indians Unsung Heroes for Lewis and Clark Deseret News May 23 1999 Lewis and Clark Center Details Indian Influence USA Today June 26 1998 Dresser Michael and Dresser Sheila A Symbol of Real American West Waterfall Baltimore Sun October 13 1997 Much work has been done in the past two decades to create public access to and public viewing areas of the dam and falls For decades two gravel spaces existed on River Drive North near the Bob Speck Municipal Golf Course where drivers could stop get out and view Black Eagle Falls and the damUda Take Newhouse Eric Winslow Larry and Loznak Robin Lewis Clark Portage Then and Now Great Falls Tribune June 26 2005 In 1991 the Rivers Edge Trail a paved and gravel pedestrian recreational trail opened along tracks of the former Burlington Northern Railroad on the south bank of the Missouri River at Black Eagle DamEcke Richard Trail a Real Survivor Great Falls Tribune June 2 2001 In 2001 Tailrace Island was renamed Black Eagle Memorial Island in honor of those workers who lost their lives while working on or at the dam and turned over to the Rivers Edge Trail A new section of the trail linking the existing trail was also opened that year The same year a public boathouse was constructed on Black Eagle Memorial Island for use by canoeists kayakers and other watercraft observation decks public restrooms and parking lot The boat landing was completed in October 2001Wilmot Paula New Canoe Landing Going In Below Black Eagle Dam Great Falls Tribune October 19 2001 Construction also began on a section of trail designed to link Art Higgins Memorial Park on the north bank of the Missouri River just behind the dam with the island Most of the construction costs were paid for by PPL Montana In 2001 another segment of the trail was added leading from the Black Eagle Memorial Island spur up Smelter HillJohannes Katie N 2002 Planned Trail Improvements Great Falls Tribune January 14 2002 The trail was paid for by a Community Transportation Enhancement Project grantThe Community Transportation Enhancement Program is a program administered by the Montana Department of Transportation which provides small grants to transportationrelated projects that strengthen the cultural aesthetic and environmental aspects of transportation The programs focus is on nontraditional projects There is no fee to enter Black Eagle Memorial Island which is open daily to the public from 9 AM to 8 PM and is maintained by the Montana Department of Fish Wildlife and ParksOutdoor Notebook Great Falls Tribune March 25 2004 In 2004 the Rivers Edge Trail was extended along the north bank of the Missouri River from the Black Eagle Dam powerhouse westward about to the 15th Street BridgeWilmot Paula City Kicks Cash Toward Soccer Park Trail Great Falls Tribune June 2 2004 About 175000 of the 204500 cost of the extension was paid for by the Community Transportation Enhancement Program and the remainder by the Montana Air Congestion Initiative a state program the American Public Land Exchange a nonprofit organization and Recreational Trails a nonprofit which manages the trailLee Sonja Island DayUse Area Open to Public Great Falls Tribune June 3 2005 Black Eagle Memorial Island opened to the public on June 2 2005Rivers Edge Trail Runs 25 miles Over Hill and Dale Great Falls Tribune March 20 2005 Babcock Michael Come for Ice Cream Stay for the View Great Falls Tribune June 2 2005 The development of the Rivers Edge Trail and the growing importance of riverside parks and attractions around Black Eagle Dam and along the banks of the Missouri River led the city of Great Falls to develop its first Missouri River Urban Corridor Plan in 2003Rivers Edge Trail Great Falls Tribune May 31 2003 The master plan which covered both banks of the Missouri River from White Bear Island to Black Eagle Dam inventoried the entire shoreline and assessed the riverbanks for condition rehabilitation and refurbishment and improvement opportunities The plan laid out a number of options above and below Black Eagle Dam for improvements to public access recreation and beautificationWilmot Paula Commissioners OK Missouri Corridor Plan Great Falls Tribune May 5 2004 Lee Sonja Neighbors Give Cold Shoulder to Ice Proposal Great Falls Tribune May 12 2004 Black Eagle Dam has changed very little between its construction in 1926 and 2010 The ruins of the powerhouses from the 1890 dam and the 1913 reconstruction were still visible as of 2005 The large castiron sheets which formed the south bank penstocks can also still be seen 腳註 Category 水壩 Category 美國水電站 Category 美國水壩 Category1890 年完工水壩 Category1927 年完工水壩 Category19 世紀完工水壩 Category20 世紀完工水壩 Category 重力壩