  We argue that the quiescent value of the viscosity parameter of the accretion
disc in WZ Sge may be alpha_{cold}~0.01, in agreement with estimates of
alpha_{cold} for other dwarf novae. Assuming the white dwarf in WZ Sge to be
magnetic, we show that, in quiescence, material close to the white dwarf can be
propelled to larger radii, depleting the inner accretion disc. The propeller
therefore has the effect of stabilizing the inner disc and allowing the outer
disc to accumulate mass. The outbursts of WZ Sge are then regulated by the
(magnetically determined) evolution of the surface density of the outer disc at
a radius close to the tidal limit. Numerical models confirm that the recurrence
time can be significantly extended in this way. The outbursts are expected to
be superoutbursts since the outer disc radius is forced to exceed the tidal
(3:1 resonance) radius. The large, quiescent disc is expected to be massive,
and to be able to supply the observed mass accretion rate during outburst. We
predict that the long-term spin evolution of the white dwarf spin will involve
a long cycle of spin up and spin down phases.
