Grease an 11x7 pan and pour blueberries over the bottom.
Combine the water, sugar, starch, and lemon juice in a small pot. Stirring constantly over medium-high heat, bring the mixture to a thickened, nearly-clear state. Remove from heat and stir in the vanilla. Pour over your blueberries and mix gently with a rubber spatula just until combined.
In a large separate bowl, combine all of the crisp topping ingredients (except the butter) using a wire whisk. Pour the melted butter over the top and incorporate with a fork until crumbly. Using your hands, sprinkle the crisp topping evenly over the blueberry filling. Bake at 350 degrees for 45 minutes or until the crisp is golden brown and the filling is bubbly.
Recipe by Yellow Birch Hobby Farm at https://www.yellowbirchhobbyfarm.com/favorite-blueberry-crisp/