Fresh Water WEP Systems and the National Water Act

What does the law (specifically the National Water Act), say about water evaporation prevention systems on stored waters?

Preventing and reducing rates of water evaporation is a “soft” intervention that conservation minded entities, such as the Southern Cape Landowners Initiative (SCLI), are investigating to protect volumes of stored waters.

In towns and cities, owners of swimming pools are investing in swimming pool covers, to prevent water from evaporating and to cope with strict water restrictions in times of drought.

Although not written into by-laws, urban water users are not forced to implement evaporation prevention measures. However, in terms of restrictions, they are not allowed to refill their swimming pools when the level drops due to evaporation.

Water users who rely on medium to large fresh water dams, especially those in the mining and agricultural sector, are increasingly looking at implementing evaporation prevention systems.

But what legal compliance issues dictate the way water evaporation prevention (WEP) systems are installed, and what are the pitfalls?

Concerns regarding the potential impacts of water evaporation systems, for instance floating covers, on aquatic habitat, are likely to be dam specific.

One worry would be that dam vegetation would be destroyed or damaged during implementation, operation and removal of the covers.

Another concern is that the exclusion of sunlight will suppress algal growth and reduce water temperature. In such circumstances, the characteristics of a water course may be altered, thereby triggering Section 21 (i) of the National Water Act (1989): Altering the bed, banks, course or characteristics of a water course.

However, should this be rated as a low impact activity, one could apply for a General Authorisation number (509 in Government Gazette 40229 of 26 August 2016).

WEP installations and the Water Act all depend on how strictly the Department of Water and Sanitation (DWS) view dam- specific installations.

Fortunately, most small and medium dams that are used for irrigation etc, would not be significantly or negatively impacted by evaporation prevention systems, and are unlikely to trigger provisions in the Water Act.

There are significant positive impacts associated with evaporation prevention systems, if installed in accordance to a maintenance plan.

Weighing up the pros and cons of installing evaporation prevention systems, we use the point of departure that dams are, by nature, impacting negatively on rivers, catchments and wetlands.

Damming up fresh water, and allowing vast amounts to evaporate from stored waters, is detrimental to both water users as well as natural fresh water systems.

With urban populations increasing their demand for fresh water, coupled with the impact of climate change on the increase, WEP systems, along with green energy and sustainable/ best practice, are sure to take their rightful place in the environmental sector.

The Southern Cape Landowners Initiative (SCLI), is a public platform for landowners and land managers who have an interest in the control and eradication of invasive alien plants. As part of its Water Stewardship Initiative, SCLI is piloting WEP systems in the Southern Cape. SCLI is supported by the Table Mountain Fund, an associated trust of WWF SA, visit for more information.

Article & Photograph: Cobus Meiring
Southern Cape Landowners Initiative (SCLI)
083 626 7619



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