The Palo Verde Irrigation District occupies about 189 square miles of territory in Riverside and Imperial Counties, California. The District contains approximately 131,298 acres, 26,798 acres of which are on the Palo Verde Mesa. This Mesa lies just west of, and from 80 to 130 feet higher than, the valley. A portion of the Mesa area lies within boundaries of the Palo Verde Irrigation District. Colorado River water, supplied through Palo Verde Irrigation District canals, is lifted onto the Mesa by private pumps to irrigate a portion of the acreage in the District. The remaining mesa irrigated acreage is irrigated from deep wells developed by the landowners. The predominant crop on the Mesa is citrus. The Colorado River, which is the boundary between Arizona and California, forms the eastern and southern boundaries of the District. The valley is relatively level; approximately 9 miles wide, 30 miles long and ranging in elevation above sea level from about 290 feet at the northern end to about 220 feet at the southern end. The soils are alluvial in nature, laid down in past years by Colorado River floods; and range in texture from fine grain clays to silty loams to light sandy soils, with the predominant soil being a sandy loam. The entire valley is underlain with permeable sand at shallow depths. The Palo Verde Valley with its long, hot growing season is ideal for agriculture; crops are grown and harvested year round. Mild winters, with a minimum of frost, permit growing of many crops not suitable for production in other areas.