Dry out the electrical connector.
Use a voltmeter to see if there is pulsing voltage when you turn on your left signals.
If there is not, then the voltage is not making it to the connector itself.
If it IS there, then the bulb is bad. (obviously your right bulb is good, so the water had something to do with it. Electricity takes the path of least resistance.. it is easier to go "around" the lightbulb, from one connector tab to the other (via the water) than it is to go THROUGH the bulb (causing it to light)..
Help it out, a little.. let it air dry, while. (maybe a little heat, a hair dryer perhaps..)
Ray