how did it get the name?
It came from the Old English word "beofor" or "befer".
Beaver
The English word "beaver" comes from the Old English word "beofor" or "befer" (recorded earlier as "bebr"), which in turn sprang from the Proto-Germanic root "*bebruz". 
what river forms the border between iowa and nebraska UNANSWERABLE which are the main tributaries of the missouri river? James, Big Sioux, Grand River systems etc. where does it originate from? It officially starts at the confluence of the Jefferson and Madison in Missouri Headwaters State Park near Three Forks, Montana. does it have any dam over it? Yes, Black Eagle Dam, Ryan Dam, Canyon Ferry Dam, etc. when was the first one built? 1890 by whom? Montana Power Company built the second dam. how is the dam operated? UNANSWERABLE does it face any issues? Yes, sediment load carried by the Missouri River and its tributaries is a problem for Black Eagle Dam. which animals are found there? Beavers, mule deer, muskrats, river otters, and white-tailed deer. what kind of an animal is the first one? They are large, semiaquatic rodents of the Holarctic.
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Beaver [SEP] Etymology
The English word "beaver" comes from the Old English word "beofor" or "befer" (recorded earlier as "bebr"), which in turn sprang from the Proto-Germanic root "*bebruz". Cognates in other Germanic languages include the Old Saxon "bibar", the Old Norse "bjorr", the Middle Dutch and Dutch "bever", the Low German "bever", the Old High German "bibar" and the Modern German "Biber". The Proto-Germanic word in turn came from the Proto-Indo-European (PIE) word "*bhebhrus", a reduplication of the PIE root "*bher-", meaning "brown" or "bright", whose own descendants now include the Lithuanian "bebras" and the Czech "bobr", as well as the Germanic forms.