they will contribute toward the first cost of the work the sum of THOMAS M. ROBINS, Senior Member. SURVEY OF KERN RIVER, CALIF. SYLLABUS The district engineer finds that floods on Kern River during 1937 and 1938 caused damage in excess of three and one-quarter million dollars, and estimates that an average annual future flood damage of approximately $879,000 will result under present conditions. He recommends an improvement consisting of a flood-detention reservoir at Isabella on Kern River with necessary appurtenant works at a total estimated first cost of $6,055,000, subject to the condition that local cooperation be required to the extent of contributing $1,055,000 to the cost of the project. He estimates annual maintenance and operation costs to be $30,000, and that direct benefits arising from this improvement will exceed the cost thereof in the ratio of about 2.8 to 1. The district engineer finds that no improvements are warranted on Poso or WAR DEPARTMENT, I. AUTHORITY 1. This report is submitted in compliance with the provisions of section 6 of the act of June 22, 1936 (Public, No. 738), as modified by the act of July 19, 1937 (Public, No. 208) and the act of June 29, 1938 (Public, No. 761). Section 6 of the act of June 22, 1936, reads in part as follows: SEC. 6. The Secretary of War is hereby authorized and directed to cause preliminary examinations and surveys for flood control at the following-named localities Sacramento and San Joaquin River Valleys, California. 2. A preliminary examination report dated April 19, 1938, was made by the district engineer as prescribed by law, was reviewed by the Board of Engineers for Rivers and Harbors and a survey was authorized by the Chief of Engineers on July 13, 1938. This authority provides for the submission of separate reports for each of the 12 stream groups covered by the appendixes of the preliminary examination report. The Kern River Group was reported upon in appendix A. Only II. GENERAL STATEMENT 3. Existing projects.-There are no existing War Department projects on the streams of the Kern River Group, and there are no requirements for local cooperation. Matters pertaining to navigation or beach erosion are not pertinent in this area, and are not considered in this report. 4. Prior War Department reports. With the exception of the preliminary examination report referred to in paragraph 2, there has been only one prior report by this Department covering streams in the subject area. This report was made under the provisions of House Document 308, and is printed in House Document 191, Seventythird Congress, second session. This report made no specific recommendations with respect to flood control, Kern River. 5. Reports by other agencies and acknowledgments.-The Kern River area, constituting an important unit in the agricultural development of California, has been reported upon for various purposes by Federal, State, and local agencies. Reports pertinent to the Kern River area are listed in appendix XII. Data obtained from these reports have been of material assistance in this study. Valuable assistance and data have also been obtained from the United States Department of Agriculture, United States Bureau of Reclamation, various agencies of the State of California and Kern County, and local interests. 6. Maps. Published maps of the area are the United States Geological Survey quadrangles, at scales of 1:31,680, 1:62,500 and 1:125,000, and United States Geological Survey maps of Kern River in the vicinity of Isabella Reservoir site at scales of 1:4,800 and 1:31,680. Maps and drawings included with this report are listed below: Enclosure number and title: 1. Locality map. 2. Isabella Reservoir and index.1 3. Isabella Dam-general layout.1 4. Isabella Dam plan, elevation and sections.1 5. Pumping and power lay-out.1 7. Inundation map and flood data.1 III. DESCRIPTION 7. General description. The area covered by this report includes the watersheds of Kern River and Poso and Caliente Creeks, their valley alluvial fans, the reclaimed Kern and Buena Vista Lake areas, and that portion of the San Joaquin Valley lying southerly of Tulare Lake Basin. (See map, enclosures 1 and 7.)2 The watersheds of this group of streams occupy adjoining areas in the mountain and foothill regions of the Sierra Nevada. The valley area which is dependent for water supply upon the run-off of these streams, commonly termed the "service area," is located principally in Kern County and includes about 1,000,000 acres, of which approximately 500,000 acres are irrigated or farmed at present. The remainder is used for grazing or is permitted to lie idle. The fertile reclaimed bed of Tulare Lake and adjacent lands in the valley trough to the south, 1 Not printed. 2 Only enclosure 1 is printed. receive excess of flood waters from Kern River, as well as from Kings, Kaweah, and Tule Rivers. These rivers are covered by separate survey reports. 8. Kern River is the most southerly of the major streams flowing into the San Joaquin Valley. It drains an area of approximately 2,400 square miles in the Sierra Nevada. The headwaters of the river consist of two main forks. The North Fork, the larger of the two, rises at an elevation of about 13,500 feet and flows almost due south for 83 miles to the town of Isabella. The South Fork rises at an elevation of about 11,500 feet and flows in a southerly direction along the eastern edge of the watershed for 67 miles, and thence westerly 15 miles to join the North Fork near Isabella at elevation 2,500 feet. The river then continues about 72 miles in a southwesterly direction past the city of Bakersfield to a point in the valley trough slightly north of Buena Vista Lake. River flows reaching this point are either diverted through a weir into the Buena Vista Lake basin for temporary storage, or are carried by improved flood and irrigation channels along the trough of the valley, toward Tulare Lake Basin, northwesterly about 50 miles. During periods of exceptionally large run-off a considerable portion of the flow is carried northerly by Goose Lake Slough, a natural distributary of Kern River. The head of this slough is about midway between Bakersfield and Buena Vista Lake. Under normal conditions of run-off the flow of Kern River below Bakersfield is gradually dissipated by diversions, seepage, and evapora tion so that Kern River water reaches Tulare Lake Basin only as a result of flood flows in late spring months. 9. Poso Creek drains 290 square miles westerly of Isabella and northerly of lower Kern River. The waters of Poso Creek are usually dissipated by seepage or evaporation before reaching the valley trough. Infrequently they reach Tulare Lake Basin but not in sufficient quantity to cause damage. 10. Caliente Creek and its main tributaries, Walker Basin Creek and Tehachapi Creek, lie southerly of and roughly parallel to Kern River below Isabella. They drain 470 square miles of semiarid land in the Sierra Nevada and the Tehachapi Mountains. Water from Caliente Creek is absorbed in the valley floor southeasterly of Bakersfield before reaching the trough of the valley. 11. Poso and Caliente Creeks are included in the Kern River Group for the purposes of this survey because of their geographical location. They are not tributary to the Kern River nor do they contribute to the flood damage caused by that stream. Table 1 gives channel lengths, elevations, and average fall per mile for streams of the Kern River Group. Channel profiles are shown in appendix III-L.1 1 Not printed. 12. Climate. The climate of the upper watershed of Kern River is characterized by cold winters with heavy snow, and warm dry summers. Temperatures range from 20° F. below zero or colder in winter, to 90° F. in summer. Poso and Caliente Creeks have their sources below 7,500 feet elevation where climatic conditions are temperate. Throughout the service area of these streams, the summers are hot and dry and the winters are mild with little frost. The average maximum and minimum daily temperatures on the valley floor approximate 80° and 50° F., respectively. 13. Physiographic characteristics.-The upper portion of the Kern River watershed is divided into two parallel basins by a high central ridge that runs almost due south from the Sierra divide to the junction of the two main forks of the river near Isabella. The North Fork, in the western basin, drains a high, extremely rugged region characterized by sharp, barren peaks and ridges, and deep canyons. Numerous small glacial lakes form the headwaters of tributary streams. The upper or northerly portion of the South Fork Basin drains a high but less rugged area. Mountain slopes are less abrupt, stream gradients are flatter, and the canyons are relatively shallow. The area is characterized by numerous long meadows separated by short reaches of steep canyon. Easterly and southerly of the main South Fork Valley the drainage area is desert-like in character, and the mountains are lower and well rounded by erosion. Below the junction of the North and South Forks, Kern River flows southwesterly through 30 miles of steep and rugged canyon to the San Joaquin Valley floor. After emerging from the mountain canyon, Kern River flows on an alluvial fan to the main valley trough. The river channel in this section has aggraded to such an extent that the stream bed is in some places several feet above the adjacent land. The trough of the main valley formerly consisted of swamp and intermittent lakes connected by meandering sloughs. This swamp area and the beds of Kern, Buena Vista, and Tulare Lakes have been reclaimed and are generally highly developed for agricultural use. Table 2 indicates a general physiographic division of the Kern River watershed by elevation. TABLE 2.-Distribution of area in zones of elevation—Kern River watershed Above 10,000.. 5,000 to 10,000. 2,500 to 5.000.. Below 2,500.. Total.. Elevation Classification:] (1). (2) (3). (4) (5).. 14. Poso Creek drains a low mountain area and flows several miles through foothills to the valley floor across a somewhat indefinitely defined alluvial fan toward the trough of the valley. Caliente Creek spreads upon an alluvial fan immediately after emerging from its foothill drainage. 15. Geology. The Sierra Nevada is of comparatively recent origin, being composed of ancient rocks which have been tilted and uplifted into a lofty block range. Granite intrusions later occurred and have been exposed by erosion. Metamorphosed sedimentaries and vol canics, which are the remnants of two older mountain ranges, are found in isolated areas. The rocks of the Kern River basin in the vicinity of the proposed reservoir are principally of those granites with occasional remnants of older metamorphics. The North Fork of the Kern River parallels, but does not occupy the trace of a prehistoric but now inactive, rift known as the Kern Canyon fault, which probably influenced present topography of the region. 16. Soils and vegetative cover.-Bare granite slopes predominate above the 10,000-foot elevation, and there is practically no vegetation. The soil cover becomes thicker as the elevation decreases and the middle elevations of the North Fork basin are heavily timbered. The southern and eastern portions of the watershed are relatively dry and vegetative growth is generally confined to juniper and sagebrush. The foothills are covered with a deep mantle of residual granitic soils broken by occasional rock outcrops. Vegetation consists principally of native grasses. The soils in the valley are alluvial sands and silts which are in general excellent for agricultural purposes. Table 3 shows the classification of the soils in the area. TABLE 3.-Classification of soils Total area, square miles 77 160 47 484 110 57.8 17.5 13.7 (1) These are the best alluvial soils of the valley, being the more level irrigable lands of medium texture and are adaptable to general crops. (2) Hardpan and associated soils of the upper valley plains fall in this classi fication. They are suitable for grazing and for growing grain and alkali-tolerant 100,0 crops. (3) Soils of this classification are poorly drained and are alkaline. They are not adapted to crop raising but produce wild grasses for pasture. (4) Steep lands of low grazing value. These soils are shallow and subject to erosion. (5) Soils of this classification are of no agricultural or grazing value. They are shallow, badly eroded, highly alkaline, and too rough for tillage. |