By A. H. Thompson.

That portion of Utah drained by the Colorado River and its tributaries belongs to a great basin limited on the north by the Uinta Mountains and on the west by the high plateaus that separate the drainage of the Colorado from that of the salt lakes of the interior, and extending beyond the limits of the Territory on the east and south. The floor of this basin is extremely rough, being broken by isolated groups of rugged mountains, by plateaus encircled with cliffs of almost vertical rock, by mesas and amphitheaters, and huge monumental and castellated buttes. Everywhere the surface is cut and carved with a network of cañons, hundreds and often thousands of feet in depth.

The main channel through which its drainage passes to the sea is the Colorado, and its proper upper continuation, the Green River.

The principal tributaries to these streams from the east are the White, the Grand, and the San Juan Rivers—all rising in the high mountains east of the Territory and flowing in a general westerly course—the White entering the Green River, the Grand uniting with the Green to form the Colorado, and the San Juan entering the latter about 125 miles below the junction of the Grand and the Green. The Virgin, the Kanab, the Paria, the Escalante, the Fremont, the San Rafael, the Price, the Minnie Maud, the Uinta, and Ashley Fork are the principal tributaries from the west.

This portion of Utah is but sparsely settled by white people, the only permanent locations being in the southwestern part, and in the Uinta Valley at the north. Information concerning its agricultural resources is limited, being confined, except in relation to the localities before mentioned, to data collected by the geographical and geological parties of this survey. Many of the streams have been visited but a single time, and different streams at widely different dates, during a field season. Often the exigencies of the survey prevented as close an examination into the flow of water, and the location and character of the soil of the arable tracts, as was desirable; yet, on the whole, it is thought that the data collected can be relied upon as a very close approximation.

The climate of the basin is one of extreme aridity. The prevailing wind is westerly. The high plateaus and mountains forming the western rim of the basin force these winds up to an altitude above the sea of over 10,000 feet, and thus act as great condensers to deprive them of their moisture. Flowing down from the higher lands into the warmer regions below, their capacity for absorption is increased, and during the greater portion of the year the winds abstract from rather than add to the humidity of the lower altitudes. But little is known concerning the actual amount of precipitation of moisture within the basin. Below an altitude of 7,000 feet it is very small, probably not over an average of 5 inches yearly. At higher altitudes it is much greater, probably reaching 24 inches, but this is mostly during the winter months and in the form of snow.

The elevation of the region under consideration is from 2,500 feet to 11,500 feet above the sea, thus giving great range in temperature. In the valleys of the extreme southwestern portion an almost subtropical warmth is experienced, and the different valleys containing arable lands we pass from these by insensible gradations to those where frosts occur during every month in the year. Generally, the limit of successful cultivation of the soil is below 7,000 feet.

In this portion of Utah irrigation is essential to agriculture. If all the single acres it is possible to cultivate without artificial irrigation were aggregated, I do not believe the sum would reach one-fourth of one square mile, and every foot of this meager amount is irrigated naturally. Springs are of infrequent occurrence. The great source of the water supply is the streams fed by the rains and snows of the high table lands and mountains. All these streams have a rapid fall in their upper courses, and are here often of considerable size; but upon reaching the lower and more level country their waters are rapidly absorbed by the porous soil and evaporated by the higher temperature. So great is the loss from these causes that some streams fail to reach the main drainage channel during the warmer months, and all are greatly shrunken in volume. All the arable lands—or lands where altitude, slope of surface, and quality of soil permit successful cultivation, if a supply of water can be obtained, and from which lands to irrigate, or irrigable lands, may be selected—are in the valleys adjacent to the streams. Usually this area in many valleys is in excess of that which the water in the streams can irrigate, and choice in the location of lands to cultivate is often practicable. In this report I have considered irrigable lands to be such only as possess all the necessary qualifications of altitude, slope of surface, and fertility of soil, and have, in addition, an available supply of one cubic foot of water per second for each hundred acres. The great dissimilarity between the valleys makes it desirable to consider the drainage basin of each separately, in respect to arable lands, irrigable lands, volume of water, and practicability of increasing this supply during the irrigating season.

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.

KANAB CREEK.

Kanab Creek rises in springs bursting from underneath the cliffs forming the southern boundary of the Pauns-a-gunt Plateau, and flows southward until it joins the Colorado River in Arizona. Small areas of arable land are found along its course after it has descended to an altitude of 7,500 feet, and thence until it passes beyond the boundaries of Utah. The largest area in one body is in Kanab Valley, at the foot of the Vermilion Cliffs. It is greatly in excess of the water supply, is at an altitude of about 5,000 feet, has a fertile soil, and requires but comparatively a small amount of irrigation. The amount actually under cultivation in 1877 is placed by the best information attainable at 700 acres. The critical period in the cultivation of this area occurs in June. At that time the stream is falling rapidly, and crops have sometimes been seriously damaged. Estimates of the volume of water in the stream, made at different seasons and in different years, give 15 cubic feet per second as the flow in June. Some desultory attempts have been made to increase the supply by ponding, the cañon through the Vermilion Cliffs above the arable lands affording many opportunities. When this improvement is made on some well considered and well executed plan, and the waterways flumed through some bad sandy ground that now absorbs much water, the amount available at the critical period can be at least doubled.

Some years ago a settlement was established at the foot of the Pink Cliffs, on the headwaters of the Kanab, but the town site was eventually abandoned because of the deep snows of winter and the frosts of summer.

THE PARIA RIVER.

The Paria River rises under the eastern escarpment of the Pauns-a-gunt Plateau, at about the same altitude as Kanab Creek, and flows in a southwesterly course for 100 miles, joining the Colorado in Arizona. Through the greater part of its course the river flows in a deep cañon, but near its head, and at an altitude of 6,000 feet, the cañon expands into a valley. Lower in its course, and at an altitude of 4,500 feet, the cañon again widens into a smaller valley. These are the only areas of arable lands within its drainage basin in Utah. The larger contains 15 and the smaller 10 square miles. In August, 1874, this stream flowed 30 cubic feet per second in the upper valley. The flow in the lower would be one-third greater. High water occurs in April or early in May. At this time the volume is three times greater than in August. Settlements have been made in both valleys, and quite a large area is under cultivation. The soil is excellent.

The critical period in irrigation is the latter part of June or early in July. At this time the stream probably carries 40 feet per second. The land in the lower valley is much subject to flooding from heavy showers that, falling on the table lands and mesas in the upper portion of the drainage basin, pour a torrent often beyond the capacity of the channel to convey through the lower valley. So great was the damage done by these floods in sweeping away dams, breaking through ditches, and inundating the growing crops at the site first selected for settlement, that it was abandoned after three years’ occupation, and other parts, where these sudden rushes could be controlled, selected. Considerable difficulty has been experienced in the lower valley from the vast amount of argillaceous sediment deposited on it. So great during the floods is this deposit from the water used in irrigation that the ground becomes completely coated with an impervious layer, and growing crops, especially of small grains, suffer from the inability of the soil to absorb the water conducted on it. The irrigating capacity of this stream during the critical period could be greatly increased by the construction of reservoirs in which to store the great surplus of water that flows earlier in the season. The cañons above the valleys offer very favorable opportunities for building the necessary dams and embankments.

THE ESCALANTE RIVER.

This stream enters the Colorado next north of the Paria. It rises under the wall forming the eastern face of the Aquarius Plateau; flows first northeast, then east, and finally southeast, before reaching the Colorado. Its length is 90 miles, the lower three-fourths being in a narrow cañon having vertical walls ranging from 900 to 1,200 feet in height. Through this gorge the river sweeps, sometimes filling the whole space from wall to wall; sometimes winding from side to side in a flood plain of sand, and always shifting its bed more or less with every freshet. Not an acre of accessible arable land is known in the whole length of the cañon, and its depth precludes the possibility of using the waters of the river on the lands above. Near the head of the southern branch of the Escalante, in what is known as Potato Valley, and at an elevation of about 5,000 feet, is an area of about 6 square miles of available land. The flow of water in this branch was 90 cubic feet per second in July, 1875. A portion of this area is now under cultivation, and is said to produce good crops. A portion of the east flank of the Aquarius Plateau is drained by a number of creeks that join the Escalante in the deep gorge below Potato Valley; but they all enter close cañons, in which no areas of arable land are known at an altitude low enough for successful cultivation. Part of the waters of these creeks might be used to irrigate grass lands at an altitude of about 8,000 feet; but the conditions of pasturage are such in this region that the amount practically available is small.

THE FREMONT RIVER.

The largest branch of this stream rises in the Un-ca-pa-ga Mountains, and after flowing in an easterly direction for 125 miles enters the Colorado about 40 miles below the junction of the Grand and Green. It is joined by one considerable tributary, Curtis Creek, from the north, and another smaller, Tantalus Creek, from the south. The lower half of its course is through two deep cañons, separated by an intervening valley called Graves Valley, in which is an area of 10 square miles of arable land, with an altitude of 4,500 feet above sea level. On the upper waters of the main river, in what is known as Rabbit Valley, and at an altitude of nearly 7,000 feet, are 25 square miles of arable land of good quality. This area, from its altitude, should be subject to late and early frosts, but the warm sandy soil and southeastern slope of the whole valley will probably prevent much damage from this cause. The valley is now used as a herd ground for cattle belonging to the settlements in Sevier Valley, and the few experiments made by the herdsmen in cultivating the soil also indicate that the danger to be apprehended is slight. The volume of water flowing through Rabbit Valley in July, 1875, was 175 cubic feet per second.

Tantalus Creek drains the northern portion of the eastern slope of the Aquarius Plateau. It enters a close cañon at 8,000 feet altitude, and continues in cañons until it has passed through Water Pocket Fold. It then flows along a desolate valley at the foot of the fold until it joins the Fremont River. During the warmer months the water in this creek is usually absorbed and evaporated before reaching its mouth. In the valley at the foot of Water Pocket Fold are about 10 square miles of arable land; but the almost inaccessible situation of the valley and the desolation and ruggedness of the surrounding country may present insurmountable obstacles to its settlement.

Curtis Creek, the northern tributary of Fremont River, is formed by the union of several smaller streams that rise in the Wasatch Plateau. Debouching from the plateau, these branches flow across what is known as Castle Valley, and here, at an altitude of 6,000 feet, are 25 square miles of good arable land. They were measured in September, 1876, and gave an aggregated flow of 47 cubic feet per second. As they derive a greater part of their waters from the melting snows on the plateau, double this amount, or 94 cubic feet, would not be an overestimate of the volume during the irrigating season. After the union of these branches, the united stream flows in a deep cañon until near its junction with the Fremont River in Graves Valley. Both Curtis Creek and the Fremont receive some accessions to their volume from springs in the cañons through which they flow above this valley. If all the water in their upper courses should be used to irrigate lands in Castle and Rabbit Valleys, a sufficient amount would be returned to their channels by percolation to irrigate, with the addition of the accessions in the cañons, all the arable land in Graves Valley.

THE SAN RAFAEL RIVER.

This stream flows in an easterly course, and enters the Green 32 miles above the junction of that stream with the Grand. It has three principal branches—Ferron, Cottonwood, and Huntington Creeks—all rising in the Wasatch Plateau at an altitude of about 10,000 feet. These streams have a rapid fall in their upper courses, and leave the plateau through almost impassable cañons cut in its eastern wall overlooking Castle Valley. They flow across that at intervals of a few miles apart, and, then uniting, cut a deep, narrow cañon through the San Rafael Swell. Emerging from the swell, the river flows across a low, broken country until its junction with the Green. The largest body of arable land within the drainage basin of the San Rafael is in Castle Valley, a long, narrow depression lying between the eastern escarpment of the Wasatch Plateau and the San Rafael Swell. It is nearly 60 miles in length from north to south, and has an average elevation of 6,000 feet above the sea. Its southern end, as has been before mentioned, is drained by the tributaries of Curtis Creek, the central portion by the three streams forming the San Rafael, and the northern by Price River. No permanent settlements have been made in the valley, but it is much used as a winter herding ground for stock owned by the settlers in other portions of Utah. Lying near the branches of the San Rafael that cross it, and in such position that the water can be easily conducted over it, are 200 square miles of arable land, generally of good quality. East of the San Rafael Swell, and lying on both sides of the river, at an altitude of 4,000 feet, are 20 square miles of arable land, which could be easily irrigated. The river was carefully measured in July, 1876, and the volume of flow found to be 1,676 cubic feet per second. The three branches in Castle Valley were also measured, with results closely approximating the measurement of the united streams. These measurements were made at high water, though not when the streams were at their flood. As most of this volume is derived from the melting snow, which rarely disappears from the high plateau before the middle of July, the flow would be maintained with considerable steadiness during a large part of what would be the critical period in the irrigation of this valley. After the middle of July the decrease would be very rapid until September, and the lowest stage of water reached about the first of October, when the river would not flow probably more than 400 cubic feet.

THE PRICE RIVER.

This river rises in the angle formed by the intersection of the Wasatch and Western Tavaputs Plateaus, receiving tributaries from both these table lands, and has a general easterly course for 100 miles. It crosses the northern end of Castle Valley, and then flows through a broken country near the foot of the escarpment called the Book Cliffs, forming the southern boundary of the Tavaputs Plateau, till within 20 miles of the Green River, when it cuts through this escarpment into the plateau and joins the Green a few miles above the foot of Gray Cañon. The arable lands along its course are mostly found in Castle Valley, where there are at least 50 square miles—a quantity considerably in excess of the irrigating capacity of the stream. The volume of water was measured in July, 1877, a few miles below where it debouches into Castle Valley, and found to be 189 cubic feet per second. It must suffer great loss from absorption, as the volume when leaving the cliffs is much greater, and the aggregated flow of the branches on the plateaus is at least twice as great.

MINNIE MAUD CREEK.

This stream rises in the broken country, where the Western Tavaputs and Wasatch Plateaus break into the Uinta Mountains. It has a general easterly course, and joins the Green midway in the Cañon of Desolation. For the greater part of its course it flows in a cañon that widens enough occasionally to give a small area of arable land. One such area, containing 6 square miles, occurs at an altitude of 5,500 feet. Here the volume of water was measured in July, 1877, and found to be 16 cubic feet per second.

THE UINTA RIVER.

This is the largest tributary emptying into the main drainage channel from the west. It rises in the Uinta Mountains, and has a southerly course for 65 miles. The Duchesne River, its western branch, rises in the same mountains, and the two streams unite only a few miles before the Uinta joins the Green. The drainage basin of the Uinta has an area of 1,300 square miles, lying between the altitudes of 4,500 and 7,000 feet above the sea. It has, generally speaking, a regular slope from the foot of the Uinta Mountains to the mouth of the streams, or in a direction toward the southeast. The surface of the basin is greatly diversified, consisting of broad reaches of bottom lands along the rivers; elevated, level, or gently sloping benches, sometimes partially arable, but oftener gravelly barrens; broken, rock-faced terraces; and low cliffs and ridges. It is difficult to estimate the amount of arable land. All the bottom lands are such, and can be easily irrigated. The streams have a rapid fall, but flow near the surface, and no deep cañons are found anywhere in the basin. This renders it possible to conduct the water over considerable areas of bench land, and wherever the soil of these is sufficiently fertile, selections of good farming land can be made. Above the limit in altitude for successful cultivation, large tracts of meadow lands can be irrigated. Those best acquainted with the extent of these classes of land place the arable, including irrigable natural meadow lands, at 40 per cent. of the whole basin. This would give an area of 520 square miles, and I do not think it is an overestimate. The volume of water flowing in the Duchesne River above its junction with Lake Fork was measured in August, 1877, and found to be 1,011 cubic feet per second. The Uinta was measured above its junction with the Duchesne in October, 1877, and then flowed 214 cubic feet per second. These streams all rise in high mountains, from whose summits the snow is never completely melted. The line of highest water is usually in June, but the flow is well sustained through July. After that the volume rapidly decreases, and lowest water occurs in October. The critical period in the irrigation of this basin would occur in August. I think it may safely be assumed that the measurements of the Duchesne and the Uinta represent the flow at the critical period, but that Lake Fork should be doubled. This would give 1,825 cubic feet per second, or enough to irrigate, at the assumed standard, 285 square miles, or 22 per cent. of the whole area of the basin, and indicates the Uinta drainage as one of the best, if not the best, agricultural valley in Utah.

ASHLEY FORK.

This stream is the most northern tributary of the Green River south of the Uinta Mountains. It rises in that range, but at a lower altitude than the branches of the Uinta, and has a southeasterly course 48 miles in length. On its lower course, at an altitude of 5,500 feet, are 75 square miles of arable land of excellent quality, a few acres of which are now cultivated. There is sufficient water in the stream during the critical season to irrigate 25 square miles.

HENRYS FORK.

But a small portion of the valley of Henrys Fork lies within the Territory of Utah, but this portion includes its best lands. A beautiful natural meadow is here found, affording a large quantity of hay to the ranchmen of that country. The altitude is great, the valley being 6,000 feet above the level of the sea, and hence liable to late and early frosts.

About 10 square miles can be redeemed by irrigation. The volume of the stream is sufficient to irrigate a much larger tract, but a part is needed for other lands which lie farther up the river, within the Territory of Wyoming.

THE WHITE RIVER.

The White River enters the Green from the east, about two miles below the mouth of the Uinta. This stream rises in Colorado, and has only a small portion of its course in Utah, but lying within the boundaries of the Territory are 75 square miles of arable land which may be irrigated with its water. The river was measured in October, 1877, near its mouth, and flowed 734 cubic feet per second. High water usually occurs in June, and the critical period in the irrigation of the land is probably in August, when the stream should flow at least double the volume of October, or, 1,468 cubic feet per second. This would be greatly in excess of the amount needed to irrigate the available land in Utah, and, from the best information attainable, it seems doubtful if it could be used higher up on the course of the stream.

THE GREEN RIVER.

Brown’s Park.—Brown’s Park is a valley through which the Green River meanders. Three or four small streams head in the mountains to the north and a like number in the mountains to the south and find their way into the river in the midst of the park. But a small portion of the park lies within Utah and the small streams will be used for irrigation in the portion which falls in Colorado. The flood plain lands of the Green are extensive, and here many natural meadow lands are found, interspersed with fine groves of cottonwood. Some of the bench lands are well adapted to irrigation, but a portion of them and the foot hills back of them are naked, valueless bad-lands.

When the general industries of the country shall warrant the great expenditure necessary, the Green will be taken out to irrigate the bench lands on either side. About 10 square miles of these bench lands will fall within Utah.

Below Split Mountain Cañon.—Lying along the Green, and between the foot of Split Mountain Cañon and the mouth of the Uinta, are 50 square miles of arable land. Some portions of this may be subject to inundations at times of extraordinary floods, but the greater part is above high water mark. Green River here carries sufficient water to irrigate many times this amount of land, and while the cost for the construction of suitable dams and canals would be greater than on smaller streams, neither this nor the engineering skill required would be beyond the resources of any ordinary settlement.

Gunnison Valley.—In Gunnison Valley, below the foot of Gray Cañon, are 25 square miles of arable land. The cost of constructing the necessary irrigation works at this point would be greater than above the mouth of the Uinta, but still not beyond the ability of a colony. Green River flowed in Gunnison Valley in September, 1877, 4,400 cubic feet of water per second, enough to irrigate at the standard adopted 860 square miles. There seems to be no arable land to which it is possible to take this great surplus, and probably for many years to come it will be suffered to flow “unvexed to the sea”.

The area colored on the map is much greater than above indicated. The selections of irrigable lands will be made on either side of the river, in patches, within the colored district.

THE GRAND RIVER.

The Grand River has but a small amount of arable land along its course in Utah, and flows for most of the distance in a close cañon. The volume of the stream, about 40 miles above its junction with the Green, was measured in September, 1877, and found to be 4,860 feet per second. It is probable that selections can be made to the extent of 40 square miles from the areas colored on the map.

THE SAN JUAN RIVER.

But little is known concerning the arable lands or volume of water in the valley of the San Juan. It flows for the most of its course through Utah in a cañon, and all the arable land is thought to be so much subject to overflow that cultivation is impracticable.

OTHER STREAMS.

A few smaller streams are also tributary to the Colorado and Green within the Territory of Utah, but they mostly flow in deep cañons, are often dry in some portion of their course during every year, have at best only a few acres of arable land anywhere along their courses, and have been omitted in this report.

The following table gives a summary of the facts relating to the flow of the several streams and the amount of arable and irrigable lands in the districts described above: