It’s a map created by the Immigrant Legal Resource Center and they host an interactive map that you can mouseover. They get their data from ICE, whose website includes a non-interactive map in the form of a PDF. ICE is encouraging people to visit their site and write to their local law enforcement, they’re not going to waste resources tracking every visitor to determine if they’re really part of the target audience for their message.

It shouldn’t need to be said that the link is to ice. The link clearly says “ice dot gov” in the text. This warning sounds overly paranoid.