Preheat oven to 375? Mix the sugar and butter until fluffy. Add the eggs, one at a time and mix well. In another bowl, combine 2 CUPS of flour, baking powder, and salt. Add to the creamed mixture, alternately with the milk and water. Fold in the sour cream and cream cheese chunks. In another bowl, toss the blueberries in the remaining 1/4 cups of flour, and gently fold into the batter. Pour into a 9" x 13" pan sprayed with nonstick spray. Combine the topping ingredients until it resembles coarse crumbs. Sprinkle over the batter. Bake at 375? for 50-60 minutes.