I had to quit doing that when we switched to scooping litter. That stuff
turns into a heavy, slick clay. Not a good idea at all!

There's always one of the organic scooping litters. I know of two:

Sweat Scoop (made from wheat, I suppose the chaff or straw), and
The World's Best Cat Litter (made from corncobs)

These are flushable (which is what we do with them), but they'd
probably also compost well.