02 Aug 2007
High levels of naturally occurring arsenic, manganese and boron have been found in the Wairau Valley west of Blenheim.
The rural area, including the Wairau Valley township is home to about 500 people and has been the subject of a Marlborough District Council ground water study over the past year.
Council hydrologist Peter Davidson said there were particular concerns about the high levels of the three chemicals, some of which were 15 times higher than the Health Ministry's drinking water standards.
He said it was too early to say how widespread the problem was but it could have implications for future residential developments taking water from the deep Wairau Valley aquifer.
The chemicals were thought to leach from the alpine fault line running the length of the Wairau Valley.
Boron and manganese were a low health risk but arsenic could cause cancerous lumps if consumed over a long period. Arsenic was measured at almost 2½ times the health standard at a new council well on Mill Road near the Wairau Valley township.
The Wairau Valley was developing rapidly with new lifestyle subdivisions.
Davidson said there was no problem with the town water supply.
He said developers were required to test drinking water in new subdivisions.