The crop dusting company I work for had just recently did a job for fish and game. The job was in a wildlife area used for public hunting and fishing. Is that considered a prevalent wage job? Also how could I find out if the job was over the min dollar amount for prevalent wage?
If you were employed on a public works project, you should have been paid prevailing wage. There are some exceptions. https://www.dir.ca.gov/ has charts to determine prevailing wage for your specific County and area of work. If you think you were underpaid, present that evidence to your employer and ask for the balance to be paid to you. You can also consult an attorney that specializes in wage and employment cases to assess your case.