Thanks for your question. I was a magistrate in small claims court in Ohio for 12 years, and I will be happy to assist you.
A verbal agreement is just as legitimate and binding as a written agreement, with the exception that a written agreement has visible proof and a verbal agreement often boils down to one person's word against the other.
Small claims courts, including those in Wisconsin, have limited jurisdiction. This means that by law, they can only decide certain types of cases. Under Wisconsin law, small claims courts can hear: claims for money in the amount of $10,000 or less; tort/personal injury actions where the amount claimed is $5,000 or less; eviction actions; replevins (i.e., the return of personal property).
Unfortunately, Wisconsin law does not permit small claims courts to hear the type of grievance you've described in your post.
Your remedy would be to continue to discuss the matter with the management at your facility in an attempt to persuade them to restore your swimming pool privileges. Hiring an attorney to assist you would likely be very helpful, as attorneys can often be more effective in such situations. An attorney could also recommend additional remedies, perhaps even injunctive relief.
Hope this helps. Good luck.