Most people think of that easement as a "free zone". This is not always true. You should still check with your local municipality as to the restrictions to these easements. Call before you dig.
No individual shall be allowed to prospect on public property including the public rights of way, nor can any individual remove artifacts from public property or public right of way without the express
written permission of the town or the appropriate legal authority controlling the right of way. The permission must be carried with the prospector at all times while searching the public property. Furthermore, no disturbances or construction activities shall be authorized within properties belonging to the town, including public streets and rights-of-way, without a town right-of-way permit and without such archaeology efforts as may be addressed by this ordinance.
http://growth-management.alachua.fl.us/historic/micord.htm
These are some of the things the "me me me" crowd purposely omit.
Added later: Folks...you do not have the "right" to dig on any ROW or easement without a locate ticket...period. If you do not know what a locate ticket is, you shouldn't be digging.