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River Mile

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River Mile

The term river mile is the distance from the mouth of the creek or river to the gage, to the nearest tenth of a mile. The distance is measured from the outlet to the sea or Puget Sound on the main stem or from the confluence with the larger creek or river. Streams are identified by stream order number to indicate their relationship in the basin network and for the calculation of river mile.

The river mile for gages were originally reported in a series of reports. The river mile for new stations are calculated in reference to locations in the index and/or from new topographic maps. River mile distances are not usually recalculated from significant channel changes by flood events, engineering changes, or geomorphic changes in the river channel since the original calculation.

The indexes were a series of "River Mile Index" Reports for individual or groups of river basins produced by the Hydrology and Hydraulics Committee of the Pacific Northwest River Basins Commission in the 1960 and 1970's, from maps provided by the U.S. Geological Survey, U.S. Forest Service, and Army Corps of Engineers, and from information provided by agencies or available points of interests. The series covers the river basins in Washington by basins or regions in the state, and for other states in the Pacific Northwest.