The Mangatainoka sub-catchment:
- is 43,000ha in area,
- land use is 47% sheep and beef, 30% dairy, 22% forest (native and exotic),
- has a number of popular swimming spots,
- has ten sites of rare/threatened native fish,
- is a regionally important trout fishery and spawning area,
- contains 1 high priority bush and 2 high priority wetland sites,
- includes the Mangatainoka scheme, and
- Te Kāuru (Manawatū River Eastern Hapū Collective) Ngāti Mutuahi, Ngāti Hāmua, Ngāi Te Kapuarangi, Ngāti Te Koro are the hapū of this sub-catchment.
The water quality of the Mangatainoka subcatchment is characterised by low suspended sediment loads, but high phosphate and nitrate levels. Pathogen levels are generally safe for swimming, except in the Mākākahi at the Hāmua site. Non-point source run-off contributes 98% of the nitrate and approximately 80% of the phosphate load. Point source discharges contribute the greatest loading during low flow conditions, when run-off from land is significantly reduced.
THE WATER QUALITY STATE IS EXPLAINED BY:
- this sub-catchment contains approximately 700ha of unprotected erosion prone land (about 2% of the unprotected erosion prone land in the entire Manawatū Catchment) and is contributing 6% of the total suspended sediment load to the Manawatū Catchment,
- there are 22 consented discharges to water in the sub-catchment. The largest four are: Pāhiatua sewage, Eketahuna sewage, Fonterra milk powder plant, and the Tui Brewery. Applications for the reconsenting of these four discharges are currently being considered
through the consenting process. The compliance rate of the discharges monitored is 100%,
- there are 94 consented dairy shed effluent discharges to land consents. Over the last 10 years all but one dairy shed effluent discharge has been diverted from water to land. The compliance rate of these consents so far this season is 84%, and
- the exact level of progress towards the Dairying and Clean Stream Accord targets (around stock exclusion from waterways, stock crossing, and nutrient management) by dairy farmers in this sub-catchment is unknown, but there is extensive riparian fencing and planting, and stock crossings (bridges and culverts). Farmer surveys in the Manawatū-Whanganui region ndicate the majority of Dairying and Clean Stream Accord targets are achieved.
- 9 man-made barriers are having a moderate to high impact on native fish migration,
- public access to the Mangatainoka River is good, although access to the Mākākahi River (a major tributary) is more limited,
- no high priority bush remnants and only 50% of high priority wetlands are protected,
- the quality of the Mangatainoka River trout fishery has declined markedly in the last 20 years, and
- the water quantity resource of the Mangatainoka sub-catchment is fully allocated. All major takes are metered and automatically monitored.