Beavers are active in Delta Ponds, even though I haven't personally been able to catch a glimpse of one. This is just one of the beaver dams in the Ponds. Unfortunately, they are sometimes vandalized, as noted in this article - http://projects.registerguard.com/rg/news/local/34459141-75/eugene-officials-please-let-beaver-dams-be-at-delta-ponds.html.csp I simply can't imagine why someone would do that! It's disgraceful!