Why is the estuary smelly?

Estuaries can have unpleasant odors due to the accumulation of organic matter, such as decaying plants and animals, which release gases like hydrogen sulfide when decomposed by bacteria. Additionally, nutrient runoff from agriculture or urban areas can lead to algal blooms, which, upon dying and decomposing, further contribute to foul smells. Low oxygen levels in the water can exacerbate these processes, leading to stagnant conditions that intensify odors.