Avon is the third and the largest of the four upper Nepean Dams. It was completed in 1927 to serve the Sydney area. The 72 metre high Avon Dam holds water from a 140 square kilometre catchment, forming a lake of 1,055 hectares, with a capacity of 214,360 megalitres. The dams of the Upper Nepean collect water from the catchments of the Cataract, Cordeaux, Avon and Nepean rivers, which are tributaries of the Upper Hawkesbury-Nepean River. These systems supply water to the Macarthur and Illawarra regions, the Wollondilly Shire, and metropolitan Sydney. Facilities include picnic shelters, electric barbecues, drinking water, toilets, disabled toilets, playground and viewing areas.