How to clean grease/lard off a manhole cover squirrels drink from?

[Rocky1]

The squirrels drink from a manhole cover in the park. Recently, I found a blob of grease that looks like lard on the manhole cover. I would like to clean it off because I am worried about it contaminating their drinking water. I cannot think of anything that cuts grease that would be non-toxic to squirrels. Please let me know if you have suggestions?

[Charley Chuckles]

Only thing I can think of is dish liquid like Dawn and a scrub brush and you'll need at least a gallon of water to rinse it all off very well.

[island rehabber]

Yep Dawn is the only thing I would trust.