 His first win was shared with Paul Glass, David Nichtern, Dominic Messinger, Kevin Bents, Lee Holdridge, Bette Sussman, and Rob Mounsey.His Directors Guild of America win was shared with Jill Mitwell, Owen Renfroe, Alan P. Needleman, 
Richard A. Manfredi, and Teresa Anne Cicala.Howarth's company, Plangent Processes, received a Grammy award for Best Historical Album in 2008, for their restoration of "", a recorded live performance by Woody Guthrie, in 1949.