  This is the report of the Computing Frontier working group on Lattice Field
Theory prepared for the proceedings of the 2013 Community Summer Study
("Snowmass"). We present the future computing needs and plans of the U.S.
lattice gauge theory community and argue that continued support of the U.S.
(and worldwide) lattice-QCD effort is essential to fully capitalize on the
enormous investment in the high-energy physics experimental program. We first
summarize the dramatic progress of numerical lattice-QCD simulations in the
past decade, with some emphasis on calculations carried out under the auspices
of the U.S. Lattice-QCD Collaboration, and describe a broad program of
lattice-QCD calculations that will be relevant for future experiments at the
intensity and energy frontiers. We then present details of the computational
hardware and software resources needed to undertake these calculations.
