WASHINGTON COUNTY, Tenn. -

As the temperatures warm up you will likely be heading to the rivers and lakes to fish, but the Tennessee Wildlife Resources Agency is warning people to be aware of possible water changes.

Fishermen come from all over to the Watauga River. Most of the time the river is calm, but Samuel Barnett says the ideal time to fish isn't when it's calm, but when the dam is releasing water. "Fish are more active when the water flows it moves more stuff down the river and so naturally people are going to come out to it to try and catch the fish."

That can also be the most dangerous time. On Saturday three men were fishing on the river when the water was released. TWRA boating officer Matt Swecker says it likely caused their boat to crash.

One of the men got pinned between the boat and a tree. "Their trolling motor became damaged from rocks in the river. In a short period of time their vessel hit a low over hanging tree in the river," says Swecker.

Swecker says the man who was pinned was Craig Malone.

Emergency responders had Malone air-lifted to the Johnson City Medical Center.

Barnett says he hates to hear about boating accidents involving other fishermen, but he knows how quickly conditions can change. "It could be at your knees, and the next thing you know it could be at your waist. It does open pretty quickly when they open the gates all the way," he said.

Now the Watauga River seems shallow and calm, but you can tell from water marks that when water is released from the dam it becomes deep and swift. "Everybody needs to keep in mind that the water is very swift and also very cold. The average temperature in the Watauga River is roughly 47 to 49 degrees during generation events," adds Swecker.

That's why Barnett encourages people to be familiar with the areas they are fishing, especially if it's below a dam.

He says he checks the TVA's website daily to see when they be releasing water and when he can expect changes.     

At last check Malone, who had to be air-lifted from is scene, is in the ICU in serious condition.

You can plan ahead to keep yourself safe. If you want to see when the TVA releases water at any of its dams click here.