Honestly, I’d be half surprised if that security guard is an actual person. The standard way to skim off of a government payroll is to create a fictitious person and start paying them a salary that just happens to go into an account you control. Or you find some rando and give them a “job” that doesn’t involve any work and simply redirect their salary into your account. Sometimes they don’t even know they’re technically working for the state until the tax bill comes in.
Unless that security guard is a close personal friend/family of someone well connected in the Water Department they probably didn’t see anything close to $300k/year.