In Wisconsin, a first offense is a civil offense. It still carries all kinds of horrible penalties which will follow you for the remainder of your life, and will make the second offense criminal. You dont need one, but I would suggest you consult with one first. Many attorneys in the GB area would give a free consultation and let you know if you have a defense.
The short answer is yes. DWI's or DUI's carry real consequences. They can be used to enhance punishment later if a new case happens. Many states have civil costs as well as criminal statutes for DWI. Please contact a lawyer in Wisconsin asap.
I agree with Attorney Redding. Wisconsin is a unique state in that the conviction is not criminal. At the same time, you must be looking out for your future in the event the police pull you over again.