If you fail to pay the citation, your license status (or privilege to drive) in CA could be suspended. The matter might also go to collections (so, you can add another $500 or so on top of the $160 you might already owe.
If your CA license is suspended, it is possible that WI might honor that suspension in your state as well (I'm not going to look up the relevant statutes, sorry). So, one way or the other, ignoring this could very well effect you even in WI.
If you want to be over it, then simply pay the fine and put it behind you.
You will have to speak to your insurance company to find out if they will bump your insurance for this violation in CA. Heck, they may never get a copy of it unless you have a CA license and they check that.