I wouldn't give up on it either, especially since it seems to be in good shape. Before hiring a lawyer and spending a lot of money, I suggest you investigate the political process in your town. Where I live, the city council can grant a variance on pretty much any subject and overrule anything any city department or commission does. THey don't want to hear from every guy who just thinks the rules shouldn't apply to them, but if you have a good story, and I think you do, you would get a sympathetic hearing here. The argument that it is still a pool because you have been paying taxes on it might or might not hold water (sorry) legally, but it would make the city council favorably inclined to listen.