Mlawula Nature Reserve - Hydrology
The Mbuluzi, Mlawula, and Siphiso rivers flow through the reserve. The Siphiso represents the only river whose catchment area is nearly included in the reserve. The Mbuluzi and Mlawula rivers are perennial. The Mlawula only became so since the irrigation of the cane fields in 1979. The remaining rivers and streams dry up during the winter months, except in some stretches such as rhino pools and croc pool. There are a number of small pans in the reserve at Ndzindza and Mbuluzi. There are three dams on the Mlawula that were originally installed by cattle ranchers as well as a weir on the Mlawula River, adjacent to Mlawula Railway Station. The Mlawula and Mbuluzi rivers are polluted by sugar, fertilisers, molasses, and high sediment loads due to commercial agriculture. These pollutants reduce oxygen levels, increase nutrients levels and turbidity. These conditions result in algal blooms and fish kills. The Mlawula and Mbuluzi are also a permanent source of alien plant seeds.