What zone are you in??? How long has it been getting flood irrigated and how big and how many pumpkins do you have? Sorry for all the questions, i know you are looking for an answer!!! I just ask because it should be ready to be harvested soon, and if it has been fine up till now then it will prolly be fine. Pumpkins do need a lot of water and I know that pumpkins can get powdery mildew when it is wet. My pumpkins/gourds have over head irrigation and they are fine. I hope i helped a little.
Sarah

the pumpkin is about 6 days old and is the size of a softball. (ive had manyyyyyy problems with pollination, now i finaly have a pumpkin) It will be completely submereged for about a day! im sooo worried, cus ive worked so hard to get one to survive

Can you try to prop it up on something?

i could try that, but it will still be full submerged. and the roots on the vine have it tethered tightly to the ground :(