Absolute miminum depth of the water should be slightly more than the length of the shell. How long is your turtle's shell? If she's a few inches, she could easily handle even deeper water. You can increase the depth slowly over time if you're worried. If the water is deep, having something like a plastic plant for her to rest on would be good. Don't forget to adjust the basking area as well--it should be easy for her to get on and should allow her to fully dry off when she basks.
Having your turtle in such shallow water is potentially dangerous. If she tips over on her back, there's a chance she could drown trying to right herself.
Next time, it would be good to start a new question in a separate post. Your question will be easier for others to see, and you'll often get more and quicker responses.
"You become responsible, forever, for what you have tamed." -Antoine de Saint Exupery-