I am no cannondale expert but I do agree with latman in that I too thinkl its genuine and again would put it at late 90's/2000ish.
An older guy in our chaingang back home in Oz had one from new. It was a quick, sharp handling machine, looked really cool in the Seaco colours.
As for Cannondale, well you cant really get a better value for money aluminium frame than a CAAD. They have it refined and developed to a fine art. This years model is the CAAD 9 and I think these are still USA made.
I would still check that its genuine as on another thread on here that was only a couple of days ago someone was asking about a Seaco team bike they had purchased, that soon turned out not to be a Cannondale at all. So compare dropouts, shape etc with pics of a genuine one as the other one was not cheap. Thats as well as the usual frame number etc.
Carlsberg dont build Singlespeeds but if they did.......they would probably look just like mine.
I've spent half my life on bikes.........the other half I wasted