When we built an 8 ac pond on our other place in the 80s the MO DoC paid for almost the whole thing and paid for the stocking as part of a soil conservation program. There were places with 8' ravines so maybe that's what opened their pocketbooks.
We receive a small subsidy from the state for not tilling the area adjacent to the creek that runs across our property, too. We can still graze it, though.