Martinko, E. A., J. Whistler, D. Peterson, J. Kastens, R. Hagen, D. Huggins, M. Jakubauskas. 2007. A watershed classification system for tiered diagnosis of biological impairments: A scalable, Central Plains focus with national applicability: Final report to the U.S. Environmental Protection Agency STAR Program. Kansas Biological Survey, Lawrence, KS Report No. 141:153 pp.