The following discussion is based upon a special study of the drainage-basin of Great Salt Lake. INCREASE OF STREAMS. The residents of Utah who practice irrigation have observed that many of the streams have increased in volume since the settlement of the country. Of the actuality of this increase there can be no question. A popular impression in regard to the fluctuations of an unmeasured element of climate may be very erroneous, as, for example, the impression that the rainfall of the timbered states has been diminished by the clearing of the land, but in the case of these streams relative measurements have practically been made. Some of them were so fully in use twenty years ago that all of their water was diverted from its channels at the “critical period”, and yet the dependent fields suffered from drought in the drier years. Afterward, it was found that in all years there was enough water and to spare, and operations were extended. Additional canals were dug and new lands were added to the fields; and this was repeated from time to time, until in many places the service of a stream was doubled, and in a few it was increased tenfold, or even fiftyfold. It is a matter of great importance to the agricultural interests, not only of Utah but of the whole district dependent on irrigation, that the cause or causes of this change shall be understood. Until they are known we cannot tell whether the present gain is an omen of future gain or of future loss, nor whether the future changes are within or beyond our control. I shall therefore take the liberty to examine somewhat at length the considerations which are supposed by myself or others to bear upon the problem. Fortunately we are not compelled to depend on the incidental observations of the farming community for the amount of the increase of the streams, but merely for the fact of their increase. The amount is recorded in an independent and most thorough manner, by the accumulation of the water in Great Salt Lake. RISE OF GREAT SALT LAKE.