SOUTH PLATTE RIVER VALLEY. South Platte River (see Pl. XIX) rises in the high mountains of South Park, in central Colorado, several tributaries converging from different directions in South Platte Canyon, which the river has cut in penetrating the Front Range. Emerging from this canyon, about 20 miles southwest of Denver, the stream enters the plains and becomes, instead of a turbulent mountain stream, a river of the plains type, flowing through a flat sandy valley and carrying at high stages considerable sediment. After leaving the mountains it flows in a nearly northerly direction for about 60 miles, receiving a number of tributaries from the mountains, the principal of which are Bear, Clear, St. Vrain, Big Thompson, and Cache la Poudre creeks, the last named being the largest. All of these tributaries, like the main stream, flow for considerable distances through agricultural regions, so that practically all of their normal flow is diverted for irrigation and domestic supply, and there is little in any of them except during abnormally high stages, due to rapid melting of snow or to cloud-bursts. Gagings furnishing valuable information concerning the flow from the mountains and the amount of water used for beneficial purposes have been made for a number of years on all the tributaries named. Large tracts of land remain uncultivated, owing to the fact that the supply of water does not equal the demand. During recent years consumers of water throughout this section have turned their attention to the storage of flood waters in reservoirs, it being possible in this way to mature later and more valuable crops than by using only the normal flow. Near Greeley, in northern Colorado, South Platte River makes a bend and flows in an easterly and northeasterly direction to the northeast corner of the State of Colorado, where it enters Nebraska. This portion of the stream is fed only by tributaries of the plains type, the principal of which are Crow, Wild Cat, Pawnee, and Horsetail creeks. from the north, and Boxelder, Kiowa, Bijou, Badger, and Beaver creeks from the south. Ordinarily none of these streams carry water except for a short time in the spring and after heavy rains. For a number of years measurements have been made along this section of the river at Kersey, Orchard, and Julesburg. NATURE OF LANDS. The lands of northeastern Colorado are, in general, of the plains type, and are utilized for the most part for grazing purposes. South Platte River traverses plains of this character for about 200 miles in Colorado, and wherever enough water has been available tracts susceptible of a high grade of intensive farming have been reclaimed. Grasses and grains of nearly all kinds, and all of the varieties of small SECOND ANNUAL REPORT OF RECLAMATION SERVICE. 164 fruits, vegetables, and leguminous plants indigenous to temperate zones can be profitably raised. The cultivation of sugar beets has of late been attracting attention throughout all of eastern Colorado, and the locality under investigation seems to be admirably adapted to this purpose wherever the water supply is sufficient. The lands are generally similar to those in the vicinity of the town of Greeley, which have become famous for their great yield of potatoes, sugar beets, and other crops suited to the climate. The soil of the river bottom is of a clayey nature, and when worked proves to be capable of producing excellent crops. Probably, however, if the plains above were to be extensively irrigated, much of the river bottom would be ruined by seepage. The soil of the plains above the valley for many miles both north and south is of a somewhat different character, being considerably more sandy and friable, but capable, with a good water supply, of raising equally good crops. It is more easily worked than the land of the river bottoms, and is especially adapted to sugar beets, potatoes, and alfalfa. As the fall of South Platte River through the plains is from 7 to 8 feet to the mile it is generally comparatively easy to construct canals for the irrigation of the bottom lands and adjacent plains. The river bottom varies in width from one to several miles, the stream meandering from one side to the other. The quantity of land which could be irrigated if there was an unlimited water supply is very considerable. There are probably 600,000 acres lying along the north side of South Platte River which could be covered by a canal taking water at or near the mouth of the Cache la Poudre and keeping as high up as the necessary grade would permit and extending as far as the line between Colorado and Nebraska. Most of this land is of excellent quality and, with sufficient water, would be capable of raising good crops. VALUE OF LANDS. Lands with satisfactory water rights and without other improvements are worth $30 an acre and upward; probably $40 an acre would be a fair average valuation at the present time for unimproved lands with good water rights, while the value of improved lands may easily run to $100, and even higher, depending upon the nature and amount of improvement. PRECIPITATION. As may be seen from the tables below, from the reports of the Weather Bureau, the rainfall varies extensively in different years. The average precipitation for the Great Plains in Colorado, as shown by the reports of the Weather Bureau, is approximately 15 inches per annum, the amount increasing in the higher regions and diminishing in the valleys. The precipitation is usually greater in the summer, often coming in the form of violent storms, resulting at times in a considerable run-off. In some seasons, however, the rainfall comes generally in gentle showers, so that the run-off is practically zero. The average of the three stations is approximately the average for the region investigated. The fact should not be lost sight of, however, that the variation of different years is very great and that in some years the precipitation during the summer season is exceedingly small, the greater part of it disappearing as the result of evaporation. Precipitation, by months, at stations in drainage basin of South Platte River, in Colorado, from 1896 to 1902. BOXELDER. Year. Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. | Annual. 1896. 1897. 1898. 1899. 1.27 1900. .18 .86 .62 6.70 ..18 0.53 0.06 3.24 1.10 2.53 2.16 1.93 3.05 2.86 0.02 0.27 0.08 17.83 21.42 16.34 1 14.42 1901. 1902. 19 63 1.62 .55 1.55 .00 .00 .21 2.96 4.18 1.89 .57 1.66 .49 .46 .13 2.47 Normal.. 65 69 1.48 1.79 3.50 1.66 2.19 1.98 1.24 17.93 17.25 50 1.51 21.56 75 .41 .68 17.02 Year. GREELEY. Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. Annual. 0.18 0.93 1.18 1.42 0.46 4.82 2.15 0.99 0.63 0.02 0.07 13.52 16.09 16.43 2.34 1.04 .30 1.85 T. .40 10.79 T. 1.07 .11 .04 .16 11.61 47 1.70 98 .88 Year. DENVER. Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. Annual. NOTE.—The mean for the stations at Kimball and Lodgepole, in Nebraska, near this region, is 16.40, the altitude being somewhat greater and the precipitation consequently being somewhat greater also. |