Lake Eteza is located 8 km south of Mtubatuba, in level terrain and at an altitude of 6 m a.s.l. The major part of the site consists of a shallow lake, rarely more than 1.5 m deep, that forms an integral part of the uMfolozi River system. Before the final rise in sea level at the end of the last Ice Age, Eteza River was a small tributary of the uMfolozi. The recent drowning of the estuary and river valley, by a sea-level rise of 100 m, enabled sediment to fill both. The substrate of Lake Eteza comprises 40 m of organically enriched mud. The modern lake is brackish, indicating periodic connection with the sea. It owes its existence to a low natural berm, deposited by uMfolozi floods, which effectively dams the Eteza River. The river's catchment is very small, and during droughts the lake's level falls. The climate is subtropical; rainfall averages 1 050 mm p.a., falling mostly in summer. Very little coastal grassland remains around the lake. Along the river, just upstream, is a small strip of indigenous forest.
The avifauna is diverse, largely as a result of the undisturbed nature of the marginal vegetation along the water's edge and the fact that several species reach the most southerly limits of their Afro-tropical distribution here. The open water occasionally supports Pink-backed Pelican Pelecanus rufescens and Great White Pelican P. onocrotalus. The marginal swamp and surrounding grassland is suitable for African Marsh Harrier Circus ranivorus, African Grass Owl Tyto capensis and Allen's Gallinule Porphyrio alleni. Eurasian Bittern Botaurus stellaris has been recorded here and the lake may support a small population of this species.
Regionally threatened species are Pink-backed Pelican (1–24, average five) and Great White Pelican (2–1 700, average 339), as well as important populations of the following congregatory species: African Spoonbill Platalea alba, Fulvous Whistling Duck Dendrocygna bicolor (1–507, average 79), Spur-winged Goose Plectropterus gambensis (1–821, average 150) and African (Purple) Swamphen Porphyrio madagascariensis (1–147, average 16). The surrounding forest patches support biome-restricted species such as Kurrichane Thrush Turdus libonyanus and Black-bellied Starling Notopholia corrusca.
Nile crocodile Crocodylus niloticus is present, as is a small population of hippopotamus Hippopotamus amphibius.
Lake Eteza is an EKZNW reserve, proclaimed in 1976. In the south it is bounded by State commonage, but otherwise it is tightly surrounded by timber and sugar cane. Agriculture poses the greatest threat to the reserve. The catchment is small, and the timber plantations reduce inflow of water to the lake. The present inflow is sometimes contaminated by the run-off of agro-chemicals. Neighbouring cane farmers appear to have an entrenched right to abstract water for irrigation purposes, and recently 30 ha of grassland in the northern section of the reserve were ploughed and planted to sugar cane. The farmers have also attempted, without success, to breach the natural berm when lake water has spread over their crops. The hippos raid the cane, without causing major damage. There is some illegal poaching of fish. Alien weed species are present around the lake, of which Lantana camara is the most serious. Cattle also graze illegally in the reserve. No permanent staff reside there, making it difficult to respond to threats.
Lake Eteza is a proclaimed nature reserve and a comprehensive and up-to-date management plan is available. It also forms part of the Kwambo Conservancy.
Ezemvelo KZN Wildlife www.kznwildlife.com