Canyon Dam was built on the Guadalupe River to control flooding and to provide a watershed during drought.  In 2002, the Guadalupe River watershed received 34" of rain in a weeks time.  This massive amount of water overwhelmed the lakes storage capacity and started flowing over the emergency spillway.    The water going over the spillway was 7 feet deep.  As you will see in the photos, the spillway is very wide so that was a whole bunch of water, 67,000 gallons per second to be exact.  Yes, per second. This overflow kept up for 1 1/2 weeks.  It carved a gorge 50 feet deep in solid limestone and exposed  terrain that had not been seen for 70-110 million years.