Heat oven to 350 F. Grease 11x7-inch glass baking dish. Combine oats, flour, brown sugar, nuts, baking soda and salt. Add margarine, mixing until crumbly. Reserve 3/4 cup mixture; press remaining mixture onto bottom of prepared dish. Bake 10 minutes. Meanwhile, combine blueberries, granulated sugar and 2 tablespoons water. Bring to a boil, simmer 2 minutes, uncovered, stirring occasionally. Combine remaining 1 tablespoon water, cornstarch, and lemon juice; mix well. Gradually stir into blueberry mixture; cook and stir about 30 seconds or until thickened. Spread over partially baked base to within 1/4 inch of edge; sprinkle with reserved oat mixture. Bake 18 to 20 minutes or until topping is golden brown. Cool on wire rack; cut into bars. Store tightly covered. NUTRITIONAL ANALYSIS per bar: * calories 272 * carbohydrates 37 g * protein 4 g * fat 12 g * calcium 24 mg * sodium 150 mg * cholesterol 0 mg * dietary fiber 2 g