Projects on land may still need to consider floating silt curtains for their site. Water will run downhill even at the slightest angle. This means rain or flooding could easily carry any exposed or unstable dirt in your site downwards towards the nearest waterway. This can make a mess of your site, as well as be incredibly destructive for the local water and the life inside.
Some states or local jurisdictions will have specific amounts of turbidity (the amount of sunlight blocked by floating sediment), allowed in public or local waterways. Violating these restrictions may result in a major delay of your site or project. It may be worth it to consult whichever department “owns” the local river or shoreline in order to see if your site is close enough to be a concern.