Thank you for your question. If you are planning on planting your lily in a basket in your pond to get it established, we would not recommend the Floating Plant Protector for your needs, as the tallest one is only 30" tall. You may need something taller to keep the turtles out.
If you are planning on planting the lily in the soil or substrate in the bottom of the pond (and with the growth rate and size of this lily, we would recommend planting it this way), we would not have anything that would work. We would suggest going to your local hardware store and getting a flexible fencing that you could set up around the lily to protect it. You would want to make sure that you would be able to remove the fencing as soon as you could, as with a giant lily, you would not want to hinder its growth by leaving the fencing in too long.