Pomahaka River

The Pomahaka Catchment has a long history of agricultural land use, in recent years (since the late 1990s) there as been a shift from sheep and beef farming to intensive dairy farming. The Pomahaka River is a wet, flashy, catchment and floods are common. Climate and soil type mean that farming in the Pomahaka catchment relies on artificial drainage predominantly in the form of tile and mole drains. 

The Pomahaka catchment is agricultural. The upper catchment is dominated by sheep and beef farming or forestry. The mid and lower reaches of the catchment are dominated by high intensity farming, mainly dairy. In recent years dairy farm conversions have become increasingly common in the middle and lower areas of the catchment, in particular the areas around Tapanui, Heriot
and Clydevale.

Between 1999 and 2008 the number of dairy farms increased from 38 to 105; average dairy farm size also increased from 179 to 197 hectares in the same period. Conversions are on-going.

The Pomahaka River is recognised as a regionally significant trout fishery and its largest tributary, the Waipahi, is also recognised as a fishery in its own right with the longest running fly fishing competition – the Waipahi Gold Medal, which attracts many anglers every year. Brown trout, rainbow trout, chinook salmon and perch are all found within the Pomahaka Catchment.

The Pomahaka is also recognized as being regionally significant for game bird hunting. It has relatively high bag limits and densities of mallard ducks.

The Pomahaka River is a high value river for many other recreational pursuits such as pig and fallow deer hunting, kayaking, rafting, swimming, walking, tramping, photography and art, camping, mountain biking, BBQ’s and picnicking.

Deteriorating water quality is a primary environmental concern in the Pomahaka River. This is reflected by increasing turbidity, nutrient concentrations and decreasing invertebrate community health with distance travelled from the headwaters. 

The upper Pomahaka and some tributaries such as the Leithen Burn and the upper Black Gully Stream generally have very good water quality. They are dominated by sheep and beef farming and have at least 10% forest cover. In contrast, streams with poor water quality (such as the Washpool Stream and Wairuna Stream) have the highest proportions of dairy farming (up to 79% landcover) with no forest cover.

The poor water quality can be attributed to the intensive agriculture and farm management practices that are inappropriate on the extensive tile drain network present in the Pomahaka Catchment.