Preheat the oven to 350°F and spray a 2-quart baking dish with nonstick cooking spray. Pour the water and salt into a medium pot and heat until boiling. Whisk in the grits, stirring briskly to keep them from clumping. Reduce the heat to a simmer and cook, stirring frequently, for about 10 minutes or until the grits are tender and thick. Stir in the butter and garlic powder.