  The bandwith, sensitivity and sheer survey speed of the SKA offers unique
potential for deep spectroscopic surveys of the Milky Way. Within the frequency
bands available to the SKA lie many transitions that trace the ionised, radical
and molecular components of the interstellar medium and which will
revolutionise our understanding of many physical processes. In this chapter we
describe the impact on our understanding of the Milky Way that can be achieved
by spectroscopic SKA surveys, including "out of the box" early science with
radio recombination lines, Phase 1 surveys of the molecular ISM using anomalous
formaldehyde absorption, and full SKA surveys of ammonia inversion lines.
