  Spacecraft observations suggest that the plumes of Saturn's moon Enceladus
draw water from a subsurface ocean, but the sustainability of conduits linking
ocean and surface is not understood. Observations show sustained (though
tidally modulated) fissure eruptions throughout each orbit, and since the 2005
discovery of the plumes. Peak plume flux lags peak tidal extension by $\sim$1
radian, suggestive of resonance. Here we show that a model of the tiger stripes
as tidally-flexed slots that puncture the ice shell can simultaneously explain
the persistence of the eruptions through the tidal cycle, the phase lag, and
the total power output of the tiger stripe terrain, while suggesting that the
eruptions are maintained over geological timescales. The delay associated with
flushing and refilling of \emph{O}(1) m-wide slots with ocean water causes
erupted flux to lag tidal forcing and helps to buttress slots against closure,
while tidally pumped in-slot flow leads to heating and mechanical disruption
that staves off slot freeze-out. Much narrower and much wider slots cannot be
sustained. In the presence of long-lived slots, the 10$^6$-yr average power
output of the tiger stripes is buffered by a feedback between ice melt-back and
subsidence to \emph{O}(10$^{10}$) W, which is similar to the observed power
output, suggesting long-term stability. Turbulent dissipation makes testable
predictions for the final flybys of Enceladus by the \emph{Cassini} spacecraft.
Our model shows how open connections to an ocean can be reconciled with, and
sustain, long-lived eruptions. Turbulent dissipation in long-lived slots helps
maintain the ocean against freezing, maintains access by future Enceladus
missions to ocean materials, and is plausibly the major energy source for tiger
stripe activity.
