Combine water, maple syrup, salt, brown sugar, lovage, sage, thyme, and celery salt in a large stockpot and bring to a boil; cook until sugar and salt are dissolved, 5 to 10 minutes. Remove pot from heat and cool brine completely.
Place turkey in a clean cooler. Pour brine over turkey. Add enough ice water to cover turkey completely. Refrigerate turkey in the brine up to 24 hours. Use weight if necessary to push turkey below surface of brine.
If you want to keep the turkey and brine in the refrigerator, do not use ice. Place turkey and brine in a kettle large enough to immerse the bird and place in the refrigerator while brining and keep cold throughout the process!
The nutrition data for this recipe includes the full amount of the brine ingredients. The actual amount of the brine consumed will vary.