Preheat the oven to 350℉. Spray an 8x4-inch METAL loaf pan with nonstick spray.
In a large bowl, use an electric mixer to combine the sugar, butter, eggs and lemon juice. In a separate bowl, whisk together the flour, baking powder and salt. Mix in half of the dry mixture to the wet ingredients. Mix in the milk. Then beat in the remaining flour mixture just until incorporated.
Add the blueberries to a small bowl. Sprinkle the flour over the blueberries and gently toss. Gently STIR in the flour-coated blueberries and lemon zest. Scrape the batter into the prepared pan, and bake for 60 to 70 minutes. Check for doneness at 60 minutes to see if a toothpick inserted into the center comes out with only a few crumbs attached. If needed, bake for 5 to 10 more minutes. Let cool in the pan on the counter for 20 minutes, then flip onto a rack to cool completely. Place a piece of waxed paper or parchment paper under the rack.
ADD THE GLAZE:
When the loaf has cooled, add the glaze. In a medium bowl, whisk together the powdered sugar, melted butter and lemon juice. Whisk in 1 teaspoon of water at a time until you have reached a nice, thick glaze consistency. Drizzle the glaze on top of the loaf. Let set before slicing.