Emittance growth seen during the last commissioning run in the bunch compressor optics section, BC1, was blamed on inadequate dipole field quality. The significant linear and nonlinear field non-uniformities generated large horizontal dispersion errors beyond BC1. The linear dispersion after BC1 was corrected using two small corrector quadrupoles placed in BC1 for this purpose, but the remaining nonlinear field caused growth of the normalized horizontal emittance of 40% or more. At best went from 1.2 m before BC1 up to 1.7 m after BC1. The problem was magnified by the larger-than-design energy spread in BC1 due to a long initial bunch length. Show Partial Abstract