2 BULLETIN 1235, U. S. DEPARTMENT OE AGRICULTURE. 



THE YAKIMA VALLEY. 



The Yakima Valley of Washington, in a broad sense, includes 

 several valleys along the Yakima River on the east slope of the Cas- 

 cade Mountains. These are situated in Kittitas, Yakima, and Benton 

 Counties. The Kittitas Valley, about Ellensburg, has an elevation 

 of about 1,500 feet, and little of it is devoted to fruit raising. Follow- 

 ing down the river the next valley is the Selah Valley, only a few 

 nines square, and below this is the upper Yakima Valley, with its 

 tributary districts, the Naches Valley and the Tieton section. These 

 are all intensively planted to fruit orchards, consisting mostly of 

 apples, and the elevation varies from approximately 1,000 feet above 

 sea level at Yakima to 2,000 feet at Tieton. Passing through a 

 narrow gap in a range of hills below the city of Yakima, the river 

 enters the lower Yakima Valley, which is much larger than the others. 

 It is approximately 55 miles long, and varies in width from 2 to 25 

 miles. The high ground east of the Yakima River is devoted 

 largely to orchards, while the area west of the river, which is almost 

 wholly included in the Yakima Indian Reservation, is mostly given 

 over to the raising of hay, grain, and other field crops, though there 

 are some orchards. 



Practically all of the cropped land in this naturally arid region is 

 irrigated by means of water taken from the Yakima, Tieton, and 

 Naches Rivers. According to the Yakima Commercial Club, there 

 is a total of 240,000 acres of irrigated land in crops in the Yakima 

 Valley, exclusive of the Kittitas Valley. Of this, approximately 

 50,000 acres are in fruit. The tree census of Washington State 

 department of agriculture shows that in 1918 there were about 2,000,- 

 000 apple trees, 500,000 pear trees, and 500,000 other fruit trees in 

 Yakima County. 



The climate of the Yakima Valley is dry, with a normal annual 

 rainfall of from 7 to 9 inches, the distribution of which is shown in 

 Table 1 . During the summer the daily range of temperature is rela- 

 tively great, often being 30°, and sometimes more than 40° F. A 

 considerable amount of wind is experienced during the spring and 

 early summer, which is doubtless a factor in distributing the codling 

 moth from one orchard to another. Table 1, taken from published 

 data of the United States Weather Bureau, gives further details as 

 to the weather during the years this investigation was in progress. 



