weeberm

Is there a tool out there that would allow me to select a portion of stream network that is within a fixed distance from a specific point on that network? I want to be able to select all portions of my stream network that are within 4 "steam miles" (not euclidean distance) of that point, both upstream and downsteam. So far I've manually selected the portions of stream within 4 miles, but it is time consumning and cumbersome. Is there a tool to automate this process, as I have upward of 40 different points?