| Browns Park | 10 | 6,400| -- | -- | | Below Split Mountain Cañon | 50 | 32,000| -- | -- | | Gunnison Valley | 25 | 16,000| -- | -- | |Grand River | 40 | 25,600| -- | -- | | +------+-------+------+-------+ | Total 2,262.4 1,447,920 -- -- | +---------------------------------------+------+-------+------+-------+ CHAPTER VII. IRRIGABLE LANDS OF THE SALT LAKE DRAINAGE SYSTEM. BY G. K. GILBERT. The field of my work in 1877 included so large a portion of the drainage basin of Great Salt Lake and so little else that it has proved most convenient to report on all of that basin, or rather on that part of it which lies within the Territory of Utah. In so doing, I have depended, for nearly all the lands draining to Utah Lake, upon the data gathered by Mr. Renshawe, of this survey, in connection with his topographic work. The remainder of the district, with very slight exception, I have myself visited. The officials and citizens of the Territory have all freely contributed such information as I have sought, and have aided me in many ways; but I have been especially indebted to Mr. Martineau and Mr. Barton, the surveyors of Cache and Davis Counties; to Mr. Fox, the territorial surveyor; and to the Hon. A. P. Rockwood, the statistician of the Deseret Agricultural Society. Mr. Rockwood prepared a statistical report on the Territory in 1875, which has been of great service to me, and he has kindly placed at my disposal the manuscript details of his work as well as the published summary. METHOD AND SCOPE OF INVESTIGATION. Where agriculture is dependent upon irrigation, the extent of land that can be put to agricultural use is determined by the relation of the quantity of available water to the quantity of available land. There is a certain amount of water needed by a unit of land, and wherever the land susceptible of cultivation requires more water than is obtainable, only a portion of the land can be utilized. But there is also a limit to the amount of water that can be profitably employed on a unit of land, and where the supply of water is in excess of the quantity required by such lands as are properly disposed to receive and use it, only a portion of the water can be utilized. In order to ascertain, therefore, the extent of agricultural land in a given district, it is necessary to make a measurement of land, or a measurement of water, or perhaps both, and it is necessary to know the amount of water demanded by a unit area of the land under consideration.