The reservoir's usable capacity is . Prior to April 2006, the usable capacity was , before the Deep Water Storage Recovery project was completed. There are fears, however, that population pressures may stretch the reservoir's ability to furnish Sydney residents with needed water well into the 21st century. The city's population is rising by about 50,000 every year. Water restrictions (limited usage purposes and times), were imposed late in 2003 and are reapplied during serious droughts, which are expected to become more frequent.