Property tax is irrelevant. They've received the services they paid for. EMS, police, transit, roads, etc.
Property taxes do not go towards infrastructure on 'private' land. It's not the public community infrastructure that is poor, it's the park's pipes. If my pipe bursts on my property, it's my responsibility. If their pipes are poor, it's the owner responsibility (which granted is weird because it is the City in this case, but the lands are certainly not public). But property taxes should not, and do not, go towards private pipes. The owner does not want to pay the millions of dollars to repair the infrastructure when they could get rid of the park and sell the land in a money making endeavor.
http://www.calgary.ca/UEP/Water/Page...s-Calgary.aspx
They've already discussed the option to sell the land to the residents, have them pay for the infrastructure (as all private owners do) and make other necessary repair and upgrades. The residents did not want to pay the 17M it would take to do so.