  In this paper, we introduce new sets of boundary conditions for higher spin
gravity in $AdS_3$ where the boundary dynamics of spin two and other higher
spin fields are governed by the interacting collective field theory Hamiltonian
of Avan and Jevicki. We show that the time evolution of spin two and higher
spin fields can be captured by the classical dynamics of folded fermi surfaces
in the similar spirit of Lin, Lunin and Maldacena. We also construct infinite
sequences of conserved charges showing the integrable structure of higher spin
gravity (for spin 3) under the boundary conditions we considered. Further, we
observe that there are two possible sequences of conserved charges depending on
whether the underlying boundary fermions are non-relativistic or relativistic.
