Can I make a 15W+ 1-5Ohm resistor? Answered

I'm making a yard sprayer with a 12V, 5amp pump.  It works great, but I'd like to add in a 2nd, slower speed setting for situations where I want less fluid going through the sprayer.  It needs to a be a simple fast/slow switch, not a variable resistor, since I need the flow rate to be repeatable and consistent.  Ideally, I'd like to make about a 2-ohm resistor, that would need to be able to handle about 15W.  Unfortunately, no local shops have anything like that, and I don't want to wait for an on-line order to get shipped.

Is there any way to make a DIY resistor to roughly achieve these characteristics?  (Like I said, the important part is that it will be a consistent resistance value, not a specific resistance value, and not burn up with 2-4 amps going through it..)