I did it for years. You can not pay an hourly wage. The work is so variable and sucks so bad that you have to pay for performance (money per ball). It is a constant underwater "easter egg" hunt. The diver must constantly be monitoring his performance and know when ball density is too low to continue. It is excellent for strong people who will work alone and require immediate gratification.
It is not easy diving, it requires maybe 30 hours underwater before you can learn to function effectively, safely and quickly in zero or near zero visibility. The diver needs to develop special, instinctive tactile response to feeling for balls which are invisible and submerged below the surface of a mucky and floculant bottom sediment. It takes a while to learn to do the hand sweep which is fast, gentle and does not result in excessive frequency of hand injuries when sharp metal, broken glass and very sharp catfish are contacted. The diver also needs to learn to navigate almost instinctively and function without the ability to read ANY guages while submerged.
All the divers I have know, do not wear fins but rather heavy rubber snow boots, ankle weights, and extra weight to make themselves a minimum of 15 lbs negative underwater which allows them to bend over and run for 3-4- or 5 hours per day underwater. In the summer the water temperatures well over 90 degrees and the necessity of wearing a neoprene hood (and full suit) to keep parasites out of the ears makes it even more stressful than cold water.
It is reasonably strenuous and it is really not "safe". It is also something that most people could probably not perform due to the mental stress of dark water, entanglements, alligators, diving in reclaimed sewage water and also the relatively frequent occurance of smashing your head into sharp metal culvert pipes that stick out from the banks.
It also requires an understanding of golf and the probable location of shots.
college kids $15 an hour is some great money 
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