Report on the lands of the arid region of the United States, with a more detailed account of the lands of Utah

by John Wesley Powell; Willis Drummond; Clarence E. Dutton; Grove Karl Gilbert; A. H. Thompson

THE VIRGIN RIVER.

This stream is in the extreme southwest corner of the area under consideration. Its branches rise in the Colob Plateau, at altitudes varying from 8,000 to 10,000 feet above the sea. It flows in a southwesterly course, and joins the Colorado beyond the boundaries of Utah. The smaller creeks draining the eastern portion of the plateau unite, after descending to an altitude of 5,500 feet above the sea, and form what is called the Pa-ru-nu-weap Fork of the Virgin. At and below the junction of these creeks, the cañon valley in which they flow widens into what is known as Long Valley. There a considerable area of available land is found. The soil is excellent, and wherever cultivated yields abundant crops. Below Long Valley the stream enters Pa-ru-nu-weap Cañon, and is simply a series of cascades for 15 miles, descending in this distance from 5,000 to 3,500 feet above the sea level. Emerging, it enters the valley of the Virgin. This valley is 44 miles in length. Its upper portion is only an enlargement of the cañon, in which small areas of available land are found. Its lower portion is a broader valley, much broken by low, basalt covered mesas, and sharp ridges of tilted sedimentary rocks. In the upper portion of the valley the river receives several accessions, the principal ones being Little Zion, North Fork, La Verkin, and Ash Creeks. With the exception of the Ash, but very little cultivable land is found along these creeks. Midway in the valley two streams enter, coming from the Pine Valley Mountains and having small areas of irrigable land along their courses, and near the foot the Santa Clara River adds its water. The united streams leave the valley by a deep cañon cut through the Beaver Dam Mountains. The valley of the Virgin has a lower altitude than any other portion of Utah, and a warmer climate. The soil of the arable lands is usually good, and wherever it is possible to irrigate produces abundant crops. Some little difficulty is occasionally experienced in the first years of cultivation from an excess of alkaline constituents in the soil, but plentiful applications of water soon remove this difficulty, and these lands often become the most productive. No reliable data concerning the amount of arable land in the drainage basin, or the volume of water carried by the Virgin River and its tributaries, have been collected. From the best information attainable, the amount of land actually irrigated in 1875, is placed at eleven square miles. This conclusion is based in the main upon returns made in 1875 to the Deseret Agricultural and Manufacturing Society, the amount under cultivation in Long Valley having been ascertained by Mr. J. H. Renshawe, of this survey. To irrigate this, all the water in most of the tributary streams is used, but a large surplus remains in the main river. The amount of arable land is far in excess of the water supply, but some considerable expense for dams and canals would be necessary to utilize the whole amount.

It is probable that a portion of the Virgin River can be used to advantage below the Beaver Dam Mountains in Nevada, and that a sufficient amount to irrigate 25 square miles can be used to good advantage in Utah.

The time when the volume of available water furnished by any stream bears the least ratio to the demands of the growing crops is the most critical period in the cultivation of the soil where artificial irrigation is a necessity. This time, depending as it does upon the crops cultivated, the character of the soil, and the source of the water supply, whether from springs or from melting snows, differs in different localities. In the valley of the Virgin it occurs in June.

At this time the river, though not at flood height, which occurs in April, carries a large volume of water, and, by reason of the source of this supply being in the rapidly melting snows of the Colob Plateau, is decreasing but slowly, and thus the amount available at this critical period bears a greater ratio to the flood of the stream than is usual in Utah. But little information has been obtained concerning the amount of water necessary to irrigate an acre. It is thought, however, to be much greater than in any other portion of Utah.