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Small streams incise the hill slopes forming tributaries to the main Kate Valley stream, which flows east to the coast. The upper reach and tributaries descend through a mixture of regenerating nature forest, gorse and pasture to the middle reach, which is in a wide flat pastoral area. Prior to agricultural development this is likely to have supported an extensive wetland. The stream is now restricted to a small incised straight channel, most probably artificially created. A small waterbody (Kate Pond) has been created here to restore Wetland values to this area.
Below Kate Pond and the rock outcrops associated with the Ella Ponds, the stream descends down a waterfall and then, relatively steeply, through areas of shrubland and low forest. For the last 300 m, the stream meanders through pasture with steep eroding coastal cliffs to a sandy beach and the sea.
A freshwater fish fauna typical of soft sedimentary catchments in Canterbury is present in the area. All the species found (by electric fishing) are native and are mainly marine migratory species (ie., have part of their life cycle at sea). Only shortfin eel and upland bully (the only species that is not marine migratory) were occasional to common in the middle reaches and rare to occasional in the upper reaches of the stream.
In the lower reaches inanga, longfin eel, shortfin eel, common bully, upland bully and black flounder (rare) were also found. While not recorded from this stream, the habitat is typical for, and may support, lamprey, common smelt and giant bully.
The waterways are subject to high turbidity during times of high rainfall and runoff from the catchment. The pasture dominated vegetation intercepts less rainfall than shrubland or forest. This increases the amount of direct runoff and therefore silt load at times of high rainfall, although water quality will improve as the Tiromoana Bush restoration project proceeds.
The Ella Pond complex consists of a permanent and an ephemeral pond and a connecting area of wetland vegetation. It was formed as a result of slumping of the adjacent side slope, which blocked the drainage of streams flowing to the coast. The ponds and wetlands formed behind the slumped material, which separates them from the Kate Valley stream. The slump landslide also reversed the flow so Ella Pond is now “up-valley”, that is the ponds drain down towards the Kate Valley stream, rather than the stream flowing into the ponds and wetland area.
While the wetland has been affected by grazing in the past there is still a strong native vegetation component including patches of purei, Juncus gregiflorus, and other rushes and sedges, and one patch of raupo. Ella Pond flows down towards the middle reaches of the Kate Valley stream, where the wetland/wet pasture is dominated by pasture grasses with occasional rushes. Ella Pond is likely to have only limited fish species present given its location above the waterfall and limited connectivity with the Kate Valley stream. Eel may be present and it is possible habitat for banded kokopu although there is limited debris that would provide the appropriate habitat diversity. Mallard ducks, paradise shelducks, little shag, kingfisher, welcome swallow, and white-faced heron have been seen associated with Ella Ponds.