If DNR is unwilling to leave some water in the pond for the tadpoles to develop enough I would first verify visually that there are tadpoles there this year and then contact the news media (ABC- NBC- CBS- Discovery Channel) anyone and everyone who will cover your story. That will put public pressure on them to do something, ie, "save the frogs". Bring up the fact that amphibian populations world wide are on a massive decline due to habitat destruction such as this. But please check first that this is not some invasive species of frog or toad that shouldn't be in your state in the first place. Then they would be seen as the heroes.