The completion of the Nepean Dam in 1935 concluded the development of the Upper Nepean catchment. The 81 metre high dam holds water from a 320 square kilometre catchment, forming a lake of 325 hectares with a capacity of 70,170 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.