Training Conundrum

Coming off of last weekend's Oly, it's suddenly time to start getting fast again, especially in the water.  It's weird because I've spent the last month in the water working towards being able to just cruise easily and evenly, but now the need for that is pretty much over.  

In the grand scheme of things, my next big thing is the Hartford Marathon. In a more immediate sense, I've got the Greenwich Point One Mile Swim in a little less than a month. Both events call for hard interval training in the water. As far as the Marathon is concerned, long runs and bike rides will cover my need for endurance training while doing uptempo intervals in the pool provides a safe way to work at higher heart rates without the risk of injury.  I'll do more uptempo work than that, of course, but as far as swimming is concerned, there's just no reason for simple aerobic work anymore.  The One Mile Swim, meanwhile, is a short race all on its own--20 minutes or less,  the equivalent of a 5k in the water. Which means improving my uptempo swimming pace. Which in turn calls for hard interval training.  

Contemplating it right now is a little mind-boggling, though.  I like working hard, but this is gonna be quite a switch from the last month. 

Anyway, I'm gonna have to spend some time thinking about how to design my workouts. If anybody has any thoughts out there, I'm open to them. 

Thanks.