The Upper Gorge sub-catchment:
- is 53,000ha in area,
- land use is 41% forest (native and exotic), 37% sheep and beef, 21% dairy,
- has a number of popular swimming spots,
- is fed by significant sections of headwaters and streams that are recognised as having spiritual significance to Rangitāne O Manawatū tupuna and Rangitāne o Tamaki Nui a Rua and Rangitāne o Wairarapa hapū as well as customary fisheries,
- has seven sites or rare/threatened native fish,
- is an important trout fishery and spawning area,
- includes the Manawatū Gorge, and contains 3 high priority bush and 2 high priority wetland sites,
- includes parts of the south Eastern Ruahine scheme and Upper Manawatū-Lower Mangahao scheme and the Mangahao power 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 Upper Gorge sub-catchment is characterised by low suspended sediment loads, but high phosphate and nitrate levels. Pathogen levels are generally safe for swimming, except downstream of the Woodville sewage discharge. Non-point source run-off is a major contributor of nutrients and pathogens at all flows. The Woodville sewage discharge contributes the greatest loading during low flow conditions, when run-off from land is significantly reduced.
THE WATER QUALITY STATE IS EXPLAINED BY:
- the sub-catchment contains approximately 1200ha of unprotected erosion prone land (3% of the unprotected erosion prone in the entire Manawatū Catchment) and is contributing 5% of the total suspended sediment load to the Manawatū Catchment,
- there are 14 consented discharges to water in the sub-catchment, only one of which is considered significant - Woodville sewage. An application for the reconsenting of the discharge from Woodville sewage has been lodged with Horizons Regional Council. The compliance rate of the discharges monitored is 100%,
- there are 74 consented dairy shed effluent discharge 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 this season is 83%, 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 stock crossings bridges and culverts). Farmer surveys in the Manawatū-Whanganui region indicate the majority of Dairying and Clean Stream Accord targets are achieved.
- 13 man-made barriers are having a moderate to high impact on native fish migration,
- public access to the Manawatū and Mangahao rivers is good,
- only 33% of high priority bush remnants and 50% of high priority wetlands are protected, and
- the water quantity resource of the Upper Gorge sub-catchment is 77% allocated, with large volumes stored and removed from the sub-catchment as part of the Mangahao power scheme. All major takes for irrigation, town water supply and industrial use are metered
and automatically monitored.