Yeah, you don't dump fuel unless you have to. It's expensive, especially in an industry with such tight margins as the airlines.
It'll typically be done in an unpopulated area, if they can, but if they were dumping over LA it means they really wanted to get it back on the ground fast.
edit: Something very odd about this case. Given the ATC recordings linked elsewhere, there was no reason for them to be dumping over populated areas - they were offered an over-water hold to do so and said they wouldn't need it. Baffling.
Very true, I shouldn't have said standard practice and should have phrased it differently as I'm sure they would rather keep the fuel than waste it as you describe.
It'll typically be done in an unpopulated area, if they can, but if they were dumping over LA it means they really wanted to get it back on the ground fast.
edit: Something very odd about this case. Given the ATC recordings linked elsewhere, there was no reason for them to be dumping over populated areas - they were offered an over-water hold to do so and said they wouldn't need it. Baffling.