Place the chicken in a 9" x 13" baking dish that has been coated with nonstick cooking spray. Pour the lemon juice over the chicken and sprinkle with the salt and pepper. Cover tightly and chill for 4 to 6 hours, or overnight. Preheat the oven to 350F. Drizzle the chicken with the melted butter and add the water to the bottom of the baking dish. Sprinkle with the oregano. Cover tightly with aluminum foil and bake for 30 minutes; uncover and bake for 25 to 30 more minutes, or until no pink remains and the juices run clear.