Tourist gem’s sparkle even purer

Nelson Mail - - FRONT PAGE - NINA HINDMARSH

The crys­tal clear wa­ters of the Te Waiko­rop­upu¯ Springs in Golden Bay have be­come even clearer, a study says.

Sci­en­tists say the av­er­age vis­ual clar­ity of the wa­ter at the pop­u­lar tourist des­ti­na­tion is 75m, up from 63m when it was first mea­sured in 1993.

Te Waiko­rop­upu¯ Springs are the largest cold­wa­ter springs in the South­ern Hemi­sphere and con­tain some of the clear­est wa­ter mea­sured in the world.

They are the sub­ject of a Wa­ter Con­ser­va­tion Or­der ap­pli­ca­tion that seeks to pre­serve their ex­cep­tional clar­ity, with hear­ings sched­uled to be­gin this week.

NIWA sci­en­tists con­tracted by the Tas­man District Coun­cil de­ployed in­stru­ments for three months between Oc­to­ber 2017 and Jan­uary 2018 at the springs near Takaka to mea­sure the clar­ity of the wa­ter. Pure wa­ter has a vis­ual clar­ity of about 83m, and the springs were now ‘‘broadly com­pa­ra­ble’’ to Blue Lake in Nel­son Lakes Na­tional Park, which has a vis­ual clar­ity of 70-80m, the study says.

Tas­man Kempthorne mea­sure­ments re­as­sur­ing’’.

There was no ev­i­dence to in­di­cate any de­cline in vis­ual clar­ity in Te Waiko­rop­upu¯ in the 25 years since the di­rect mea­sure­ment of 63 m was made, he said.

How­ever, cam­paign­ers say they re­main con­cerned.

Save Our Springs co-or­di­na­tor Kevin Mo­ran said while he was ‘‘de­lighted’’ at the study’s find­ings, he was still very con­cerned about the im­pact of in­ten­sive dairy farm­ing on the aquifer’s health.

Mo­ran asked why ni­trate lev­els mea­sured in the springs were con­tin­u­ing to rise.

‘‘I also won­der why the lev­els of ni­trate mea­sured at Te Waiko­rop­upu¯ are 40 times that of other Takaka water­ways?’’

Mo­ran said hun­dreds of tons of ni­trates were es­ti­mated to leach from neigh­bour­ing dairy farms into the aquifer.

It took about 10 years for most of the wa­ter from the aquifer to make its way to the sur­face of the springs – about the same length of time in­ten­sive farm­ing had been mayor Richard said the new were ‘‘very oc­cur­ring in the Takaka Val­ley.

This meant we ‘‘didn’t know yet’’ what was to come from the past 10 years as a re­sult of in­ten­sive ir­ri­ga­tion and the ex­ten­sive use of urea fer­tiliser, he said.

Nel­son iwi Nga¯ti Tama ki Te Wai­pounamu Trust and An­drew Yuill have ap­plied for a Wa­ter Con­ser­va­tion Or­der for the springs and as­so­ci­ated wa­ter bod­ies. The ap­pli­ca­tion in­cludes a draft or­der, which ap­plies to the springs, the aquifer, hy­drauli­cally con­nected ground­wa­ters, the Takaka River and all its trib­u­taries.

Te Waiko­rop­upu¯ hold ex­tremely high spir­i­tual sig­nif­i­cance for Nga¯ti Tama, which pro­poses to iden­tify and the pro­tect out­stand­ing val­ues as­so­ci­ated with the springs and recog­nises it­self as kaiti­aki (guardian) of it and the aquifer. It seeks to pre- serve the aquifer in its nat­u­ral state.

A Wa­ter Con­ser­va­tion Or­der would pro­vide the high­est pos­si­ble pro­tec­tion for the springs.

The first hear­ing is sched­uled to be held at Takaka, start­ing on Tues­day.

The coun­cil said the springs’ clar­ity was mea­sured us­ing a beam trans­mis­some­ter which cap­tured 60 mea­sure­ments in one­minute bursts ev­ery 10 min­utes, re­sult­ing in al­most one mil­lion data-points.

As the project ran over sev­eral months, it also pro­vided a com­pre­hen­sive data set to as­sess how vis­ual clar­ity varies over dif­fer­ent time scales, from hours to months.

‘‘Given the time taken and num­ber of data-points gath­ered we can have a high level of con­fi­dence in the re­sult,’’ Kempthorne said.

He sug­gested the mea­sure­ments were likely to be re­peated at reg­u­lar in­ter­vals, per­haps ev­ery five years, to give the com­mu­nity re­as­sur­ance that noth­ing was chang­ing with the pu­rity of the Springs wa­ter.

The re­cent mon­i­tor­ing also mea­sured tem­per­a­ture, dis­solved oxy­gen and tur­bid­ity at the Springs.

NIWA would com­pare the re­sults to the coun­cil’s reg­u­lar wa­ter qual­ity sam­pling and that of the Friends of Golden Bay.

The clar­ity mea­sure­ments found small daily vari­a­tions cor­re­spond­ing to about 1-2m, with the high­est vis­i­bil­ity at mid­night, and low­est around mid­day.

This was likely to be due to plants in the spring basin re­leas­ing light-scat­ter­ing oxy­gen bub­bles as they pho­to­syn­the­sise dur­ing the day.

Un­der­wa­ter video demon­strated that ‘‘danc­ing"’ white mar­ble sands on the floor of the springs co­in­cided with some short-term episodes of re­duced vis­ual clar­ity, last­ing between a few hours and sev­eral days.

Vis­ual clar­ity was as low as 4m for a short time in mid-Jan­uary fol­low­ing al­most 240mm of rain­fall that re­sulted in sur­face wa­ters en­ter­ing the springs’ basin from the sur­round­ing bush re­serve.

Te Waiko­rop­upu’s clar­ity ap­peared to re­sult from ex­tremely ef­fi­cient nat­u­ral fil­ter­ing re­mov­ing par­ti­cles within the Springs aquifer be­fore re-emer­gence of the wa­ter.

CHRIS CONROY

Te Waiko­rop­upu Springs is one of Golden Bay’s most pop­u­lar tourist at­trac­tions.

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