Status of Water Resources

STATUS OF WATER RESOURCES IN THE MGENI SYSTEM AS AT
11th MAY 2018

The level of Albert Falls Dam has been steadily increasing over the past three months (February – April 2018) following good rains and releases from Midmar Dam. Estimates by the Planning Department of Umgeni Water show that improvement amounts to approximately 1% per week. On Friday, 11th May 2018, the level of Albert Falls Dam was at 55, 16%. Albert Falls, the largest dam in the Mgeni System, has been worst affected by water shortages in the Mgeni System and at the height of the crisis two years ago it reached a low of 20%. The Mgeni System is an interconnected network of dams, a weir, water treatment plants, pipelines and reservoirs.

Albert Falls is one of four dams in this system; the others are Spring Grove, Midmar, Nagle and Inanda. There is also a weir in the Mgeni System, known as Mearns. Levels of the other dams and the weir in the Mgeni System on 11th May 2018 were:

  • Spring Grove: 98, 34%
  • Midmar: 100, 15%
  • Nagle: 87, 58%
  • Inanda: 76, 42%
  • Mearns: 103, 12%

The Mgeni System collectively supplies an estimated 80% of the water needs of the eThekwini region, all of Msunduzi and uMgungundlovu and parts of Ugu. Albert Falls Dam supplies the water needs of a significant part of Durban and it is dependent on rainfall and water transfers from Midmar Dam in order to reach a state of adequacy. Downstream, Nagle Dam is dependent on rainfall, or releases or overflows from Albert Falls Dam to augment its resources.

Water restrictions of 15% for commercial, industrial and residential and 50% for irrigation were first gazetted in 2016 and extended for a year in 2017. These restrictions are legally binding, still remain and apply to eThekwini, Msunduzi, uMgungundlovu and parts of Ugu. The decision to motivate for the Ministry of Water and Sanitation to implement mandatory water restrictions was taken by the Department of Water and Sanitation and supported by the Mgeni System Joint Operations Committee, a multi-stakeholder forum established to monitor water savings and propose strategies to achieve these savings.

At the beginning of the dry season in May, Umgeni Water and the Department of Water and Sanitation run hydrological models to establish risk of non-supply from the system in the event of a drought occurring. Models that were run in early 2018 show that, based on current consumption levels, the Mgeni System has to be at a minimum combined storage level of 70% at the beginning of May in order to ensure that there is no risk of prolonged supply failure over the next two years.

On 24th March 2018 the system improved to combined storage in excess of 70%. The Mgeni System Joint Operations Committee agreed that if the system exceeded 70% storage capacity, there would probably be no need for restrictions as the system would likely remain at this level or exceed it between then and May. As a consequence, curtailments (restriction of the flow from water treatment plants) were released and full supply to the municipalities of eThekwini, Msunduzi and uMgungundlovu resumed.

It is likely that a decision will be taken at the 18th May 2018 meeting of the Mgeni System Joint Operations Committee that the Department of Water and Sanitation prepares and sends a motivation to the Ministry of Water and Sanitation supporting the lifting of restrictions. The Ministry will make the final decision on whether restrictions should be removed or kept.

Stakeholders will be informed, via Umgeni Water’s website and the media, of the outcomes of the Mgeni System Joint Operations Committee’s 18th May 2018 meeting.