AMOUNT OF WORKABLE GRAVEL IN CALIFORNIA. 77 The reports of the State Engineer of California (1880) and of Lieut.-Col. Mendell, U. S. A. (1882), give the fol­lowing data of the estimated amounts of workable gold deposits remaining along the rivers of the principal hy­draulic region on the west flank of the Sierra Nevada in California:
	Since Mr. Hague's report upon Eureka Lake proper­ty (1876), wherein it is stated that the quantity to be mined between the Yubas was 700,000,000 cubic yards (roughly estimated), explorations have proven that this estimate is too large. It is true that there was that quan­tity of gravel, and perhaps more, in that locality. But since then a quantity, possibly exceeding 100,000,000 yards, has been mined out, and the result of the work has prov­en that a portion of this gravel channel can never be mined profitably, for the reasons, 1st, that it is capped with lava and cannot be hydraulicked, and it will not pay to drift; and, 2d, another portion is so situated that it is impossible to drain it, or it is too far from the streams to dispose of the debris. It is now estimated that not more than 400,000,000 cubic yards of gravel remain here available for washing. * Report on Mining Debris in Cal. Rivers, by Lieut.-Col. G. H. Mendell, U.S.A., p. 35.