Many years ago me and a group of friends from college took a canoe
trip from the dam at Lake Whitney, Texas for several miles downstream
back to where we rented the canoes from.
On this pleasant trip I noted that the valley the Brazos River sits in
is quite wide, certainly wide enough for a Cessna to drop down into
and fly just above the river. I was sharing this verbally with my
friends, including my college roommate, who noted the huge group of
power lines stretching across the river just south of the dam (you can
see them on the sectional that includes Waco, L. Whitney is NW of
Waco). http://skyvector.com/ (type in ACT)

Several weeks later I took my roommate flying and we rented a 172 from
ACT at Texas Aero.
I planned on going to the tiny airstrip at Lake Whitney State Park and
hanging out at the Lake for a while so we headed NW from Waco Regional
(ACT).
A little ways from Waco I remembered the Brazos River Valley and how
much fun it may be to drop into it and fly along the river below
treetop level. I cancelled radar coverage and dipped below the trees
and began, nervously (I'd never been below trees except for T/O &
landing before), to meander about 20-30 feet above the river. It was
fun and scenic and the valley was very wide so I had little concern
until, after a few minutes, my roommate remembered the power lines! He
rather timidly said something like; "Hey, Ricky, weren't there some
power lines stretched across the river somewhere?" My heart went into
my throat and I yanked back on the yoke, quickly pulling out of the
river valley. Seconds later, a huge group of power lines passed
underneath our quickly - climbing Cessna 172!
We both remained speechless until landing at L. Whitney State Park a
few minutes later. He said he never even saw the power lines and had
no idea we were in danger. I told him that we very nearly lost our
lives if it weren't for his remembering them!

Power lines are inherently difficult to see because they are thin and
often blend into the landscape (I learned that from flying balloons,
they're a balloon's worst enemy in approaching a landing field or
flying low).

So I learned on that day long ago that I should think & plan long and
hard before doing something as risky as flying a river valley. I
should at least be very familiar with all nearby obstructions.
I learned that I should be extra vigilant insofar as looking outside
and ahead while doing something like this. The river and valley were
pretty, so much of my time was spent looking out the side windows, not
ahead.
The other thing I learned is that perhaps taking risks such as this
would not be in my best interest and that putting my life and
another's at peril is a thing to be avoided.

You may not want to share your story for various understandable
reasons, but if you have learned about flying from an occurance such
as is found in the back of Flying Magazine, please share! We may all
benefit from your insight.......and it may even save a life.

Ricky