Despite the decline in dam levels due to the heatwave in Gauteng, the Department of Water and Sanitation has appealed to the public not to panic.The department's spokesperson, Sputnik Ratau, told News24 that the current heatwave which the country has been grappling with in the past week has resulted in high rates of evaporation leading to dwindling dam levels."The current national average has declined to below the 75% level," he said.Despite being concerned about the heatwave, the department said that there needn’t be any panic and that water users should rather work with their municipalities and government in reducing consumption.Read: Christmas heatwave predicted for Gauteng, as Vaal Dam water levels drop"As the heat wave is predicted to continue, we would like to encourage all water users to be considerate whilst using water to rehydrate as well as other uses," said Ratau."Let us all be conscious of the delayed rains thus it will take time to recharge the water courses, including groundwater," he added.News24 reported earlier this week that the South African Weather Services (SAWS) warned of a heatwave in Gauteng and several other provinces over the Christmas holiday period."A heatwave with persistently high temperatures is expected in Gauteng, western Highveld of Mpumalanga, SW Bushveld of Limpopo, North West, Free State, northern and north-eastern parts of the Northern Cape until at least Wednesday," SAWS said on Sunday.Heatwave conditions continue today in Gauteng, parts of Mpumalanga, Limpopo, the North West, Free State and the Northern Cape. The high tempertatures have resulted in some dam levels dropping. #eNCANow Courtesy #DStv403 pic.twitter.com/AE1jO43q1y— eNCA (@eNCA) December 26, 2018In July, SAWS forecaster Edward Engelbrecht said that South Africa was likely to experience a delay in rainfall patterns this summer. He said temperatures were also expected to be higher than normal.In addition to the heatwave, residents can expect a 70% chance of an El Nino occurrence, which began mid-spring and will continue into summer."It causes below normal rainfall in summer rainfall areas and higher than normal temperatures from December to February," explained Engelbrecht."It occurs mostly in the north-eastern parts of the country. There will definitely be above normal [high] temperatures in the northern parts of South Africa."El Nino is the warming of sea-surface temperatures in the equatorial Pacific Ocean, which influences atmospheric circulation, and consequently rainfall and temperature in specific areas around the world, according to SAWS.