With sunny skies and balmy temperatures, Friday would have been a perfect day for nine holes at Cedar Glen Golf Course. But a freshly constructed dam - a 25-foot-wide mound of stripped branches and bark - had turned swaths of pristine greenway into swampland. The course was so waterlogged Thursday by beavers’ handiwork that Burton Page, who runs the business, was forced to close down for the day, estimating $10,000 in lost revenue.