The catchment for Yeramba Lagoon comprises an established residential area and part of the Georges River National Park. Yeramba Lagoon is located within the national park and was an estuarine system prior to the 1960s. The lagoon has been closed to tidal flows from the Georges River since construction of the weir and culverts in the 1960s. Lack of tidal flushing and ongoing sewage overflows and stormwater inputs from the upper catchment have resulted in the lagoon becoming highly eutrophied.
Noxious and environmental weeds are a major problem in the lagoon and its drainage lines. Weeds are encouraged by high nutrient conditions and lack of tidal flushing. They out-compete native species, cause loss of habitat, and their die-off contributes to eutrophication, odour problems and loss of amenity.