Board Thread:General Discussion/@comment-50.132.65.99-20141023181838/@comment-7971816-20141023215215

Electricity from a dam is very common. In MW's case, the network of electricity is probably hooked onto the power generator that gets power from the dam. These connections are underground.

The water supply comes from an underground reservoir.

The symbol can mean quarantaine, but Mount weather could perhaps contain a nuclear power central in it's 600.000 square feet, but it's unlikely to me. Another option is that of warning for radiation, dating from 97 years ago in the nuclear apocalypse...