Given the task definition and input, reply with output. Write an inquisitive question about a specific text span in a given sentence such that the answer is not in the text.

Sentence: Officials said there were at least 700 Coloradans still listed as missing in Boulder and Larimer counties after the disaster , which has washed out bridges and roads and isolated several central Colorado communities .<sep>Span: isolated several central Colorado communities
What communities were isolated by the flood?