We show that if an orientable
Seifert fibered space M with an orientable genus g base space admits a strongly
irreducible horizontal Heegaard splitting, then there is a one-to-one correspondence
between isotopy classes of strongly irreducible horizontal Heegaard splittings and
elements of ℤ2g. This correspondence is determined by the slopes of intersection of
each Heegaard splitting with a set of 2g incompressible tori in M. We also show there
are Seifert fibered spaces with infinitely many nonisotopic Heegaard splittings that
determine Nielsen equivalent generating systems for the fundamental group of
M.