In Dutch oven with tight fitting lid, bring blueberries, 1/2 cup sugar, 1 cup water and dash of salt to boiling. Cover and simmer 5 minutes; add lemon juice. Stir together flour, 1/4 cup sugar and 1/4 teaspoon salt. Cut in butter until like coarse meal. Add milk; stir only until moistened. Drop from tablespoon into bubbling sauce, making 6 dumplings. Cover tightly; simmer 15 minutes without uncovering. Serve hot. Sprinkle with sugar, if desired. Serves 6.