Wollondilly River Subcatchment
At 2699 square kilometres, the Wollondilly River subcatchment is the largest in the Hawkesbury Nepean catchment.
The Tarlo River National Park protects a section of the Tarlo tributary and the river flows into the reserved lands associated with Lake Burragorang.
The subcatchment contains significant agricultural lands and associated industries, which were developed early in European settlement and carry through to the current time. As with many such areas, since European settlement the Wollondilly subcatchment has been significantly altered. Significant riparian and floodplain vegetation has been cleared for grazing, native riparian trees were replaced with exotic and invasive Willows (Salix sp.) and intact valley fills have been gullied due to changes in runoff.
The subcatchment contains a rare river channel type, the "Meandering lateral" type, which is of high environmental significance due to its rarity. Significant community based environment activity exists in the subcatchment.