Lightening safety question

[kerry]

Yesterday I was paddling the South Platte river in Denver with a friend. It began raining so we pulled over to the shore under a small tree to put on our rainjackets. As we were standing on the shore, lightning struck the grove of trees across the river from us, less than 50 yds away. Needless to say, it scared the **** out of us.
My question is, what is the safest place to be in that kind of situation? Obviously, under a tree on the bank was not it. However, the general rule is to find a ditch and crouch down. Since the river is the lowest point in the area, is crouching beside the river the best course of action? Or, is it even safer to be in a plastic canoe on the water? There were high tension electric lines on our side of the river. Is lightning attracted to or repelled by them? We ended up running about 50 yds from the river to a small building at a nature center. But we were exposed and about 10' higher than the river level at that point. It was raining heavily by this time and the natural reaction is to find shelter from the rain as well as the lightning. Not sure that is wise since whatever shelters you from the rain is higher than the surrounding land.
That was about as close to a lightning strike as I ever want to get. The thunder was deafening.