with respect to age discrimination only, housing reserved exclusively for senior citizens.

First of all the burden is not on the private citizen, the police can knock, break down your door, arrest you, and generally whatever else they want to do, this doesn't make it legal or in any way acceptable, and you should pursue damages in the case that they police are at fault. 

Senior Citizens Only!

And there can be special rules regarding senior citizen tenants, too.  

But from my own perspective as a US citizen resident in Canada I must say that Canadian law makes it easier and safer to be a landlord from a purely practical standpoint.

You may have to speak to them a few times before they make any changes.If that doesn't work, then you can call the Citizens Service Bureau and they will report the problem to the appropriate organization while you will remain anonymous.

And in that first really bad year, we just changed our focus from renting to mainly working people, to students, and we even quickly filled the building back up with just a different type of tenant.And the jobs and rents came back with a fury, as you know, within a short period of time.That was the worst crash I'm aware of in my lifetime, and I'm a senior citizen, native Californian.  

If there is potentially illicit activity going on, I would think it's worth having the conversation.

Fresno has 80K more people and a State University which can produce more educated citizens. 

Are you a Mexican citizen?