You can use floating flies with casting line, by putting a float/bobber a few feet ahead of the fly. This will keep the weight of the line from pulling a small fly under water. It will also give you some weight to cast. To get the last length of line to float, you can dress it with flyline dressing(wax) this will help keep things above the water too.

Here is a link to an appropriate float for the mission:

http://www.cabelas.com/cabelas/en/templa...rset=ISO-8859-1

I would go with the clear model.

Good luck!