I'd hire an attorney and fight it if I was you. The full text of the RCW you were cited under can be found at: http://apps.leg.wa.gov/rcw/default.aspx?cite=46.37.010. The WSP rules can be found at http://apps.leg.wa.gov/rcw/default.aspx?cite=46.37.010. It seems like a good attorney could make a good argument on your behalf based on the way the laws are written.
Usually with traffic infractions there is very little case law and interpretation of the statute is left solely to the judge. However, because traffic stops for cracked windshields have resulted in discovery of evidence of other crimes there have been some higher court opinions written on this. I have had a lot of success arguing this issue on motions in criminal court. However, it is imperative that you have someone take lots of photos of the windshield in its present condition immediately. You should have someone who doesn't have an interest in the case and can appear in court to testify to the authenticity of the photos take the pictures. (Backup option: buy a disposable camera and have the film developed ASAP so that you have a receipt.) If you don't have photos the only thing that will matter is the officer's opinion of whether the windshield was dangerous. With pictures you have a fighting chance.
The answer provided is for educational purposes only. It does not constitute legal advice or create an attorney-client relationship. You should consult an attorney for legal advice regarding the facts of your specific case and designed to help you with your personal needs.
I agree with both posts by the attorneys above. I routinely get these tickets dismissed in Kansas, by showing the judge that the field of vision isn't obscured by the cracks, etc. I would consult with a local attorney and take pictures immediately. Good luck.
You should hire an attorney. If you can't hire an attorney you should mark your ticket contested and go to court and explain this to the judge yourself. Just make sure your file your ticket in a timely manner. Also, if you repair your windshield the judge would likely reduce your fine, maybe even to zero, for repairing the window. Sometimes it's easier to fix the issue than fight over things. The same officer may ticket you again, and again, and again, for the same thing if you don't fix the window. You might be able to keep getting the tickets dismissed but, in the long run it might be simpler to fix the window.