As we prepare for the storms that may follow Isaac into our area, we are reminded of the possibility if downed power lines and power outages that can accompany storms.

Wind and strong storms aren't the only things that can effect transmission lines. In many cases, massive power outages can begin with just one tree hitting a line.

Each year power outages can cost the U.S. up to $80 billion, and many of those cases are caused when trees and power lines get too close together.

Tennessee Valley Authority let us join them in their helicopter as they examined transmission rights of way to prevent these incidents.

"It gives us an aerial perspective. It allows us to get into an area with terrain that we may or may not be able to traverse with vehicles, and gives us a chance to do a rapid inspection of the lines," said TVA Line Applied Services Manager John Dooley.

They use not only their eyes, but a LiDar radar beneath the helicopter to scan for objects, and those objects aren't always trees...

"We also look for civil encroachments while we're up there. if somebody has put a barn, or some type of a shed out, we'll go out and visit with them and identify if we need to move it or not," said Dooley.

While a single tree disrupting a power line's path seems small, it can be that one tree that causes a major blackout.

"We had a first hand experience in the blackout in 2003. When we went back and did the investigations, there was a single tree that initiated that event. Now, there were hardware failures after the tree went to ground, but the initiating event was that tree," said Dooley.

All of this effort is to ensure TVA can help maintain public safety, and provide reliable energy.

The general rule for a tree near power lines is the tree cannot be more than 15 feet tall, and the distance from the lines depends on the voltage of that transmission line. For more information on those rules, and to contact TVA visit www.tva.com/power/rightofway/index.htm.