Beaver impact the natural environment like no other species, with the exception of Homo sapiens. The School of Conservation has offered classes in beaver ecology for over 30 year, because of the positive ecological impacts associated with this 'keystone' species. Beaver are the largest rodents in North America and one of the most important mammals in New Jersey. Their dam-building habit creates aquatic habitat for numerous other species from insects to mammals - producing not only new habitats, but whole communities.
Fairly recently, investigators using Google Earth have located what they believe to be the longest beaver dam on record - a whopping 2790 feet long! The dam is located in Northern Alberta, Canada, just south of Lake Claire inside the Wood Buffalo National Park. You can check out all the details for this phenomenal natural structure here: http://www.geostrategis.com/p_beavers-longestdam.htm