A lot of it used to be natural: there'd be a creek, and the beavers would dam it for them, and the farmers would use the water underneath, the flooded water, for watering their crops.
(A lot of it; to be; natural) (the beavers; would dam; it; for them) (the farmers; would use underneath; the water)
A lot of it the beavers the farmers
to be would dam would use underneath
natural
it for them
the water