NOAA has a Open Rivers Initiative which was started in 2005, with the goal of providing funding and guidance for river-barrier removal projects. 

As a part of their Merrimack Village project, they have installed a "Dam Cam", which has documented the removal of the Merrimack Village Dam in 15-minute increments.  The NOAA website is at www.nmfs.noaa.gov/habitat/restoration/projects_programs/crp/damcam.html, which explains the initiative and the Merrimack project

The really cool part of the Dam Cam is access to the photo archives through an intuitive interface, which allows you to view photos from the same point of reference over the duration of the project.  The high-quality photographs can be panned and zoom, and the coolest feature of the web interface allows you to super-impose a portion of photographs on top of each other.  The site location is shown below in Figure 1.  Click the image to link to a Google Map page

Click here for link to the webcam  WEB CAM

Figure 1 Site Location

Figure 2  Aerial looking South at the Dam