  Water plumes erupting from the `tiger stripe' features on the south pole of
Enceladus are thought to connect to a global subsurface ocean. Proposed origins
for the initial stress necessary to form the `tiger stripes' include a giant
impact, which would require true polar wander to explain the location of the
plumes if the impact did not occur at the South Pole, or tensile stresses,
which would require volumetric expansion associated with partial freezing of
the subsurface ocean. In addition to the requirement of a fine-tuned impact,
true polar wander, or partial freezing of the subsurface ocean, a further issue
with these hypotheses is that the `tiger stripes' may be short-lived. We show
here that impact resurfacing can seal off plumes and mass loss can lead to
their compression and closure over $\sim 1 \mathrm{\;Myr}$. Since plumes are
observed at present, a mechanism by which new plumes can be generated every
$\sim 1 \mathrm{\;Myr}$ and by which such plumes are most likely to form at the
south pole is needed. We propose and investigate the possibility that impacts
constitute an adequate repeating source for the continual instigation of
fractures and plumes. We find that the rate of impacts on Enceladus suggests
the formation of $\sim 10^3$ independent plume systems per Gyr, the vast
majority on the south pole, and is consistent with the Cassini-derived age of
the south pole for a lunar-like bombardment history, our estimates of fracture
lifetimes, and with the needed parameters for parallel fracture propagation.
The model favors a bombardment history similar to that of Triton over one more
similar to that of the Galilean satellites.
