This study examines the question of income adequacy as it relates to the broader issue of an economically viable farm size in the Columbia Basin of Washington State. The issue is especially relevant because of possible limitations on farm size resulting from enforcement of the 1902 Reclamation Act. Income estimates derived under two alternative accounting frameworks - the standard economic accounting method and the after-tax cash flow accounting method - were examined. Findings were that the after tax cash flow accounting framework was more appropriate for examining the income adequacy aspect of the viability issue as it incorporated the effect of federal income taxes and farmer's equity, both of which are important determinates of income levels. Using the after-tax cash flow accounting framework, the after-tax cash flow for a representative 320 acre farm was found to range between $16,858 and $42,670 depending upon the profitability of the selected crop rotation.