  This Letter of Intent outlines a proposal to build a large, yet
cost-effective, 100 kton fiducial mass water Cherenkov detector that will
initially run in the NuMI beam line. The CHIPS detector (CHerenkov detector In
Mine PitS) will be deployed in a flooded mine pit, removing the necessity and
expense of a substantial external structure capable of supporting a large
detector mass. There are a number of mine pits in northern Minnesota along the
NuMI beam that could be used to deploy such a detector. In particular, the
Wentworth Pit 2W is at the ideal off-axis angle to contribute to the
measurement of the CP violating phase. The detector is designed so that it can
be moved to a mine pit in the LBNE beam line once that becomes operational.
