Which body of water is often protected naturally from storms by barrier islands and also contains a mixture of fresh water and salt water?

The body of water, which is often protected naturally from storm by barrier island and also contain a mixture of fresh and salt water is ESTUARY.
An estuary refers to a partially closed body of water, that have one or more rivers flowing into it and which has a connection to the open sea. Because the fresh and the sea water meet at this point, the water is always a combination of salt and fresh water. A good example of an estuary in America is the Chesapeake Bay.

Answer : romans built laws to manage the pollution which was lead by smoke produced by the factories.

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.