If you are crossing Austin's iconic 360 Pennybacker Bridge and you say "Look at those people skiing on the river..." the locals know that you are just visiting or you just arrived in Austin. After you have been in Austin for a short while you will discover that the locals never refer to the Colorado River as a river. Lake Austin. Plain and simple. Yes, it may look like a river, but that does not matter. It is one of our landmark lakes.
The locals refer to the dammed bodies of water in Austin as lakes. Lake Travis. Lake Austin. Town Lake. If you tell someone that you want a home with a view of the river, you might end up looking at houses in San Marcos. At very least, you are going to be asked for clarification as to what river you might be asking about. And for goodness sakes, don't call it the Colorado River. No one in Austin knows where the Colorado River is located! In Austin we believe that the river is a place that has no near by dams--like the Guadalupe or Rio Grande. Lake Austin is...well...a beautiful city side lake.
This secret is brought to you by the Austin Committee on Local Compliance. Sometimes it is easier to just go with the flow than to re-educate 1.8M people.