Anywhere that announces itself as a Sanctuary City is guaranteed to have out-of-control local costs and require significant increases to taxpayer bills, as well as potential cuts to integral services like city employees, policing and sanitation to make up the difference. Either that, or run a massive deficit.
It's like opening up a restaurant and letting people eat for free - it's just not sustainable and you will have to eventually pay the tab, either through cuts to existing services or higher tax bills.