 Between 1890 and 1940 , five dams were built in the vicinity of Great Falls to generate power from the Great Falls of the Missouri , a chain of giant waterfalls formed by the river in its path through western Montana . Black Eagle Dam , built in 1891 on Black Eagle Falls , was the first dam of the Missouri . Replaced in 1926 with a more modern structure , the dam was little more than a small weir atop Black Eagle Falls , diverting part of the Missouri 's flow into the Black Eagle power plant . The largest of the five dams , Ryan Dam , was built in 1913 . The dam lies directly above the 87 @-@ foot ( 27 m ) Great Falls , the largest waterfall of the Missouri . 
 Between 1890 and 1940 , five dams <a href='uninflect' title='1'><mark>were</mark></a> built in the vicinity of Great Falls to generate power from the Great Falls of the Missouri , a chain of giant waterfalls formed by the river in its path through western Montana . Black Eagle Dam , built in 1891 on Black Eagle Falls , was the first dam of the Missouri . Replaced in 1926 with a more modern structure , the dam was little more than a small weir atop Black Eagle Falls , diverting part of the Missouri <a href='null_genetive' title='2'><mark>'s</mark></a>flow into the Black Eagle power plant . The largest of the five dams , Ryan Dam , was built in 1913 . The dam <a href='uninflect' title='3'><mark>lies</mark></a> directly above the 87 @-@ foot ( 27 m ) Great Falls , the largest waterfall of the Missouri . 
Between 1890 and 1940 , five dams was built in da vicinity of Great Falls to generate power from the Great Falls of the Missouri , a chain of bigass waterfalls formed by the river in its path through western Montana . Black Eagle Dam , built in 1891 on Black Eagle Falls , was the first dam of the Missouri . Replaced in 1926 with a more modern structure , the dam was little more den a small weir atop Black Eagle Falls , diverting part of the Missouri  flow into the Black Eagle power plant . The largest of tdafive dams , Ryan Dam , was built in 1913 . The dam lie directly above the 87 @-@ foot ( 27 m ) Great Falls , the largest waterfall of thdaissouri .