How about doing nothing at all!
Vernal pools are so unique that they often have plants that can only be found there and no where else. They are also unique in offering breeding sites for amphibians during this time of the year.
It is my belief that if you were to modify the area around the pool that you may be endangering both the animals and some of the plants that grow there.
Please reconsider. You may wnat to see if any local university have researchers who are into studying such pools and by giving them an opportunity to check yours out you might be able to learn alot about it and also find out if doing any landscaping around it would be advisable or not.

Here is a link that might be useful: Vernal pools