Nebraska’s Water Supply.

Nebraska’s Water Supply.

HE great water shed of Nebraska, sloping from west to east, has been compared to a veritable roof, its geological strata rising course on course as you climb from the eave trough, the Missouri river, to the ridgepole at the western border. This comparison, so far as geological strata is concerned, is a true one, but a comparison of surface altitudes will show’ that there is a ridgepole extendtending east and west, with decided sloping roofs to both the north and south as well as to the east. Along this second ridgepole, flowing across the entire state, is the Platte river, a very important factor in the water supply of Nebraska, being higher than the country either north or south of it. Across section running through Sterling, Col., Sidney, a point on the North Platte river, Alliance and Chadron, Neb., five places on a direct line north and south, shows Sterling on the South Platte river, altitude 3,795 feet, Sidney, on the Union Pacific railroad, 4,090 feet. Point on the North Platte altitude (estimated by multiplying distance from North Platte, Neb., by 10¾ feet per mile), 4,246 feet, Alliance 3.968 feet and Chadron 3,360 feet. Thus it will be seen that the North Platte is 451 feet higher than Sterling on the south and 886 higher than Chadron on the north, Chadron being north of the headwaters of the Niobrara river. A cross section on the longitude of North Platte running through McCook, on the Republican river, on the south, and Valentine on the Niobrara river, on the north, shows McCook and the valley of the Republican to be 290 feet below the Platte and Valentine 217 feet below the Platte. About thirty miles north of North Platte are the headwaters of the South I.oup river, which flow’s almost due east and at this point is more than 100 feet below the valley of the Platte, and is below the entire extent of its course to a junction with the I.oup.

Another cross section running through Kearney at an altitude of 2,146 feet shows Ravenna, on the South Loup, only twenty-five miles distant, to be 148 feet lower, Loup City, on the Middle Loup, fifty-six feet below, anil Ord, upon the North Loup river, to be ninety-five feet below the Platte at Kearney, and Bloomington, on the Republican river, almost upon the south line of the state, to be 263 feet below the Platte a Kearney. Now a very casual examination of the map of Nebraska will show that no streams of importance flow into the l’lattc until the Loup is reached at Columbus. It will also be noticed that the many small streams which flow into the Republican river, which crosses the west half of the state near the south border, flow almost directly south from points but a few miles south of the Platte river, and that the entire valley of the Republican river lies about 250 feet below the level of the Platte and almost parallel with it. On the north it will be noticed that there are no small streams flowing north, but that there are various streams which flow an easterly course, uniting to form the Loup river. All these streams lie at a lower level than the Platte, varying from ninety to 200 feet. Prof. L. E. Hicks, state geologist, in his report for 1892 says: “The drainage of the Loup region is incomplete in the sense that drainage lines have not yet been established in extensive areas, amounting by careful estimate to 35 per cent, of the whole region. If however, we regard the total overflow from the basin as the index of completeness of that drainage we shall find that it compares favorably with neighboring regions. It lacks a forest cover and might therefore be expected to suffer heavy losses by evaporation. Still the percentage of that rainfall which flows out through the river is surprisingly large. Humphry and Abbott in their exhaustive report upon the Mississippi River and its tributaries estimated the drainage of the Missouri valley at 15 per cent, of the rainfall. Since the Loup region falls w ithin the latter basin, and has much the same physical aspect as its neighbor in the same treeless region, we might theoretically be justified in accepting the estimate made by Humphry and Abbott as applying to it as well as to the larger region of which it is a part. An outtlowing of 15 per cent, would give 3,523 cubic feet per second for the mean annual volume of the Loup. On the 24th of June, 1S91, I found by measurement 7,065 cubic feet per second flowing in the Loup near its mouth. It never runs dry, never even runs low’. The Platte, which on the same day was dischaiging at Columbus he enormous volume of 18,240 cubic feet per second, often goes dry above the mouth of the Loup, but never below’. The Loup probably discharges 25 per cent, or more of the rain fall on its basin. For the explanation of this anomaly we must recur to its topography and geology. These means are the porous and uneven surface of the count)y, and the great mass of absorptive and permeable tertiary rocks lying upon a sloping floor of impervious cretaceous shales, into which the main Loup has cut its channel. Of these two sets of conditions the geological structure is the more important. It furnishes a deep, spongy mass for the occlusion of the storm waters, whence they escape so slowly that the outflow of one rainy season extends over to the next one.” Has not Mr. Hicks overlooked one important element in accounting for the phenomenal discharge of w’ater by the Loup, viz., the seepage from the Platte river between North Platte and Columbus, into the basin of the South Lcup, which lies below the Platte in its whole extent. It is a well-known fact that the North Platte never runs dry, but between North Platte and Columbus the amount of water in the Platte river is a very’ uncertain quantity, while that of the Loup and Republican rivers is much more stable. If the theory is correct that these two rivers are to a certain extent vicarious channels for a portion of the waters of the Platte river, there is a practical point in which the people of the Platte valley proper between North Platte and Columbus are vitally interested, viz., that the possibility of diverting the waters of the North Platte into the Middle Loup by artificial means, owing to its lower level be not allowed to the detriment of the Platte valley. Another, more directly interesting Lincoln is that if the project which has bean considered of taking a canal from the Platte in the region of Kearney to supply Lincoln should ever materialize there might be danger of this supply being seriously affected by the local use of the water along the Platte and its divertance to the valleys of the Loup and Republican.

But I can see no reason why Lincoln cannot go directly north with a canal not over forty-five miles in length, barring necessary sinuosities for maintaining proper levels, and tap the Platte river at an altitude of about 1,350 feet, giving a fall of about 200 feet, or at least four feet per nr.le, and having the entire body of the combined waters of the Platte and Loup rivers to draw from, where at all seasons and under all conditions there is plenty of water. There can be no serious engineering difficulties in the way of such a project. While l have not been able to find any exact or even approximate map of the geological strata of this section of the State, it is highly probable that in the case of the Platte, as in that of the Arkansas river between Hutchinson and Wichita, Kas., there is a floor of impervious cretaceous formation, which rises sufficiently to form a dam across the State and prevent outflow of the sheet waters, which are much more constant in all the country west of Lincoln than in its immediate vicinity. This supposition would seem reasonable in view of the fact that the Platte east of its junction with the Loup is a constant stream with a large flow of water. The Loup, which before its junction with the Platte lies at a.lower level, does flow over such a formation, and it is highly probable that the same ledge tends to concentrate the sheet water of the Platte valley above the ledge into the river below. It seems to me that this is a question of great moment to Lincoln, and one well worth following out. Whatever practical difficulties might appear I do not know, but 1 do know that Lincoln lies nearly 200 feet below an unlimited supply of pure mountain water at a distance of less than fifty miles, with an easy down grade all the way, barring a possible ridge of a few feet in altitude near the river. The development of such a canal with Lincoln’s location and present advantages as a railroad centre would mean a city of a quarter of a million in another decade.

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