New York Times article.....US State Dept warning

Where the crocodiles live there are mangroves. Mangroves are very important, read about them. They are responsible for a lot of the smell.

The opening of that area is open to the ocean many many months of the year, I don't remember how many, but most. During the dry season, winter, when the tides are often lower, the entrance gets blocked and the water isn't free flowing. Periodically either the little sand bar opens naturally or someone opens it. Then the water that has been trapped flows out into the ocean. A natural cycle. It's not sewage or anything manmade. Mother nature doing her thing.