In a large saucepan combine sugar, cornstarch, and salt. Add the water and lemon juice. Add 2-1/2 cups of the blueberries; toss lightly to coat. Cook and stir over medium heat until bubbly. Cook and stir for 2 minutes more (mixture will be thick). Remove from heat and stir in butter; cool.
Add remaining 3-1/2 cups blueberries to cooled filling, stirring gently. Turn into Lemon Pie Shell. Cover and chill at least 2 hours before serving. If desired, serve with vanilla ice cream.
Lemon Pie Shell
In a medium bowl stir together flour and sugar. Using a pastry blender, cut in butter until pieces are pea-size. In a small bowl combine egg yolk, water, and lemon peel. Gradually stir egg yolk mixture into flour mixture. (Dough will not be completely moistened.) Using your fingers, gently knead the dough just until a ball forms. If necessary, cover dough with plastic wrap and chill for 30 to 60 minutes or until dough is easy to handle. Preheat oven to 450 degrees F. On a lightly floured surface, roll pastry from center to edges into a circle 12 inches in diameter. Line a 9-inch pie plate with pastry circle. Trim pastry to 1/2 inch beyond edge of pie plate. Fold under extra pastry. Crimp edge as desired. Generously prick bottom and side of pastry in pie plate with a fork. Prick all around where bottom and sides meet. Line pastry with a double thickness of foil. Bake for 8 minutes. Remove foil. Bake for 5 to 6 minutes more or until golden. Cool on a wire rack.