Recent studies [see 1 of references at end of paper] seem to indicate that there is no definite oasis for selection of a design formula for a non‐silting and non‐scouring channel. One reason for this lack is the failure or inability, except in the case of the Lacey formula, to include the effect of the size or mechanical composition of the bed‐material and the solids load, as well as the magnitude of the load. In connection with certain studies dealing with the Imperial Desilting Works of the All‐American Canal, it was necessary to determine the maximum size of material that might be delivered to the desilting works by the Colorado River and also what sizes could be carried in the channels beyond the canal‐intake. Various formulas or experience data were considered, but only those judged after careful analysis to be relevant, usable, and most reliable were employed. Since, as will be shown immediately below, these formulas yield a definite particle‐size criterion for a stable channel in erodible material, in that they correlate the maximum transportable size and certain hydraulic channel characteristics, they are presented here together with a comparison of the results obtainable with them.