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Watercourse size class

Planning diagnostics

A planning heuristic that groups watercourses as river, medium stream, small stream, or very small stream using professional judgment informed by drainage area, flow, channel dimensions, hydrologic characteristics or permanence, and landscape context. The classes are intended to support ecological planning and should not be interpreted as formal hydrologic classifications or objective natural categories. Tributary order and network position provide additional information about connectivity and flows but do not determine the size class.

Strahler, A. N. (1957). Quantitative analysis of watershed geomorphology. Transactions, American Geophysical Union, 38(6), 913–920. Vannote, R. L., Minshall, G. W., Cummins, K. W., Sedell, J. R., & Cushing, C. E. (1980). The river continuum concept. Canadian Journal of Fisheries and Aquatic Sciences, 37(1), 130–137.