The Delta is one of the three most important wetlands in Catalonia. Lagoons are typical in the delta landscape and they are scientifically very interesting because of their ornithological richness. They are also important as a place of reproduction of littoral fishes and other rarer fishes like the Aphanius Iberus. The biggest lagoons, like Ricarda and Remolar, placed in the littoral line, present a natural condition; the smaller ones have diferent origins. They all are of sweet salty waters with a gradient depending on the distance to the coast.

The plain lands, without relief, depressed and often flooded are called marshes. The depth of the flooded areas hardly ever reaches half a meter high. The vegetation includes herbaceous plants, reeds and salty plants, depending on the salinity. Marshes are indissolubly linked to lagoons. They are, in fact, the richest environment for fauna in the Delta. They are a breeding, resting and nourishment place for many migratory birds, among them ducks and waders stand out. Their richness is shown in toponyms like the "Filipinas" marsh, also called "Coto Africa ", evocative names of paradisiacal places full of birds.

In the Delta we find some of the stone pine groves on dunes better preserved in the whole Catalan littoral. They constitute a scanty habitat that has been declared as priority conservation area by the European Union.

El Prat and Viladecans' beaches have important natural values, since they keep the flora and fauna communities which are typical of coastal sandbanks. Additionally they make their public use compatible with the conservation of their habitats.

The river is the essential structure of the territory and it is the responsible for the Delta's formation. It plays a very important role as a biological connector between the littoral and the interior, and it is also an axis of natural communication between the municipalities of the region, with a very important recreative potential.

A very rich intensive agriculture is carried out in the Delta, associated with waters from the channel Derecha del Llobregat and from the deep aquifer. Culture fields are protected, mostly as an agrarian park, and they act as a cushion area between urbanized areas and natural spaces.

The protected areas of the Llobregat delta have almost six kilometres of littoral land. The delta platform is very rich in invertebrates that live in sandy soils as well as in fishes. It holds a very important marine bird fauna, with big concentrations of Balearic Shearwater. It even has cetaceans like mule dolphins and striped dolphins. The organic remains that reach the coast serve as food to a community of invertebrates that are later consumed by migratory waders.