Some of our members are firm believers in these critters as ecosystem engineers. This recent article and study provides good overview at new data on historical range of beavers in CA and ecological restoration benefits. If you get really jazzed about this, look for the group and support their endeavors by donating to their Kickstarter campaign. The recent article in Bay Nature Magazine is located here:

http://baynature.org/articles/beavers-used-to-be-almost-everywhere-in-california/