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One of the society's main goals is to develop and implement plans to restore and improve the water quality and condition of the upper Wainuioru River for future generations. Another is to have scientific evidence to be used when regulations are considered for waters in the eastern Wairarapa.

    With advice and assistance from Ministry for the Environment and Greater Wellington Regional Council scientists, society members are carrying out quarterly water quality tests at six sites.

    Besides locations on the river at Ngatahuna in the north and at Te Wharau Road, testing is being done on four tributary streams – Makahaka (on Glenlean in the north-east), Whakatahine (on Brancepeth), Upokongaruru (on Hakakino) and Kuamahanga – close to where they feed into the Wainuioru.

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In 2011–12 the Greater Wellington Regional Council carried out a pilot investigation of water quality in the Pahaoa catchment, including the Wainuioru. It used two sites in our area, one at the Brancepeth bridge and one at the Te Wharau Road bridge (aka the Bankview bridge).

    Below are extracts from the report. Bear in mind that it was written in 2012.

 

    Water quality data from six sites located on the Wainuioru and Pahaoa rivers indicate low to moderate degradation...

    Application of the GWRC’s WQI [water quality index] to median values from the pilot investigation data-set resulted in the three sites located on the Wainuioru River, and the site Pahaoa River at Ngakonui Bridge, being classed as ‘fair’. The remaining two [Pahaoa River] sites, which were the two most downstream sites sampled in the catchment, were classed as ‘good’...

    All six sites failed to meet the visual clarity guideline and three sites exceeded the E. coli guideline (Wainuioru River at Brancepeth Bridge, Wainuioru River at Summer Hill Road and Pahaoa River Ngakonui Bridge). The DRP [dissolved reactive phosphorus] guideline was also exceeded at all three sites located on the Wainuioru River...

    Dissolved oxygen, nitrite-nitrate nitrogen and ammoniacal nitrogen guidelines were complied with at all six sites...

    Analysis of macroinvertebrate communities... at the eight sites assessed [two more were visited once] generally indicated ‘fair’ to ‘good’ health...

    While measures of periphyton* biomass (chlorophyll a) were typically low, three of the four core sites assessed for streambed cover exceeded the MfE (2000) guideline for filamentous periphyton streambed cover on one occasion during this investigation and the Wainuioru River at Summer Hill Road exceeded on two occasions...  General observations made during the investigation further indicate that, similar to other rivers located in the eastern Wairarapa, proliferation of nuisance periphyton growth is likely to regularly occur in some reaches of the Wainuioru and Pahaoa rivers.

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*periphyton = aquatic plants that live attached to the riverbed and submerged objects.

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For the full report, go to page 24 at: http://www.gw.govt.nz/assets/council-publications/Annual_Freshwater_Quality_Monitoring_Report_for_the_Wellington_Region_2011-12.pdf