In 2-quart casserole, mix blueberries, water, and 1/2 cup sugar.
Cook, covered, at HIGH for 5 to 7 minutes or till boiling.
Meanwhile in bowl, combine flour, 1/4 cup sugar, soda, and salt.
Cut butter into flour mixture till mixture resembles coarse crumbs.
Stir in buttermilk just till flour is moistened.
Drop batter atop hot blueberry mixture, making 6 dumplings.
Cook, covered, at HIGH for 4 minutes or till dumplings are done.