Here is a link to the Canyon Lake Gorge slideshow: http://www.canyongorge.org/media/videos/5/gorge-documentary-clip .
The 2002 Flood
The flood beginning July 4, 2002 was the first time that floodwaters flowed over the Emergency Spillway since the Reservoir was completed in 1964.
The upper part of the Guadalupe River Watershed officially received 34 inches of rain in approximately one week. (see the Canyon Lake tab for more info)
All lakeside and River Road campers were evacuated and parks closed.
When the floodwater was at peak flow, it was moving at about 67,000 cfs* approximately 7 feet above the Spillway. Normal flow from the reservoir is 350 cfs with a maximum release of 5000 cfs.
Just under 1-1/2 times the amount of water stored in the lake (at normal level) went over the Spillway during the flood event.
Water continued to flow over the Spillway for approximately 6 weeks. Rocks, trees, logs, and other flood debris piled up in the Guadalupe River and created a huge blockage. Flooding continued from the dam to the Gulf Coast. (Information taken from Canyon Lake Gorge Website)
I took the Gorge Tour about two years ago. It is absolutely amazing that this natural marvel is in my backyard. The tours are by appointment only so you must visit the Canyon Lake Gorge website in order to sign up. It is a three-hour tour so bring water and wear good shoes or hiking boots. If you still have energy following the tour I recommend walking across the dam. It is about a mile over and back. The views are some of the best of Canyon Lake. 
If you still have enough motivation after hiking the Gorge and the Canyon Dam trail get back in you car and drive the South Access Road just about half way past the dam. Look for a small “Nature Trail Sign” pull over and park. You will find the entrance to the Guadalupe River Trail. The trail closely follows the Guadalupe River as it leaves the dam.
In another post I will introduce the trails located on the North Shore of Canyon Lake.