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., \,l ,. BUREAU OF RECLAMATION REPORT capacity. Land class boundaries were plotted on topographic maps at a scale of 400 feet to the inch and from these maps acreages were computed. Soil borings were made or pits dug wherever necessary, with a minimum of 1 hole for each 40 acres. The holes were put down to a depth of 5 feet except in areas where rock or gravel was encountered. Deeper holes, to a depth of 10 or 12 feet, were dug with a power auger on representative areas throughout the project. These deep profiles were examined to deter- mine the character of the substrata, depth to impervious material, and probable subsurface drainage. Subsurface data were also obtained from the river cuts, exposed terrace banks, and from deep test holes drilled by geophysical parties prospecting for oil. Specifications used in establishing land classes were formulated by the Bureau of Reclamation on the basis of chemical and physical proper- ties of the soils and topographic and drainage features. Six land classes were established as follows: Class l--Land highly suitable for irrigation farming; capable of producing any crop climatically adapted to area. Class 2--Land moderately suitable for irrigation farming but less desirable than Class 1 land because of soil, topo- graphic, or drainage deficiencies; capable of producing any crop climatical~ adapted to area. Class 3--Land of restricted suitability for irrigation farming because of pronounced deficiencies in soil, topographic, or drainage factors; suitable for hay and grain crops but with costly farm practices; particularly adaptable to pasture. Class 4--Land with one or more excessive deficiencies that prevent production of rotational crops; suitable for pasture or meadow land. Class 5--Land considered nonproductive because of excessive salt content, lack of natural drainage facilities, or both; not reclaimable under present conditions. Cla.ss 6--Land considered permanently nonarable. The survey showed a total of 75,310 acres of arable land, as delineated on the map on the following page. Of this land 60,720 acres were conSidered irrigable and were chosen for project development. Arable lands excluded from the project include 3,300 acres above poten- tial canals, 1,010 acres of Class 5 land which would have been too costly to develop, 1,880 acres re~uired for public rights-of-way, 700 acres in isolated locations} and 7,700 acres of Class 4 land, suitable for pasture but for which no water would be available. Land USe Lands in the project area would be utilized for the support of livestock enterprises} particularly dairying. Land classes in the area are so intermingled that land in each class would be included in most of the farm units. In general Class 3 and 4 lands in farm units would 9