It's almost certainly NStar's problem; the electric utilities started out as electric and light utilities, and have mostly kept that role in our area. However, NStar has a reputation for fixing lights very slowly, with a large number of total lights out in a given city (I think there was an article about this in Cambridge within the last year, in the Globe or the Chronicle, but I can't find it right now). Some cities are dealing with this problem by exercising provisions in a 1998 law to buy the lights back from NStar so they can maintain them themselves and fix streetlights more quickly.

So I think your options are:

(a) wait, because NStar doesn't care about you and doesn't have to;
(b) research city buybacks of lighting and lobby the mayor and your alderman on the subject.