Before going over to Colorado Kiteforce, i figured Id ask here first. Does anyone know of anywhere in Colorado where there is kiteboarding in summer, or is it just too damn cold? Lake Dilllon maybe?

You cannot kite Dillon Reservoir, you can't even water ski or wakeboard, basically no body contact.
If you could the winds are two gusty and you could potentially get stuck out in the cold ass water.
Also beginners would go out and freeze their asses off if they can't stay up.

I have heard of guys doing Green Mountain
Seen guys on Boulder Reservoir

Curious about Lake Granby??

But Mcconaughy is your best bet