Periodically the city of Bakersfield has the Carrier (Kern Island) Canal dredged out and the bottom dregs (muck) dumped haphazardly nearby.
Contrary to common belief, this dirt or is not rich with nutrients; as the silt builds up in the canal, the lower layers become oxygen-deprived and lifeless.
So, instead of fertilizing the land on which they are dumped, they smother it. Eventually, enough bacteria may infiltrate the dirt and bring it alive, but only over the passage of time. The thinner the spread, the less time that will take.
Care needs to be taken that the city dredging contractors know this. They also need to know they should not dump the muck into historic river channels. Such care has been lacking.