Lake water pipe survey sparks warnings

Environment Bay of Plenty fears some Lake Rotoiti residents may still be drinking water from the lake in spite of repeated warnings that it is unsafe to do so.

During a recent survey of the lake’s edge, kayakers logged more than 50 inflow pipes originally installed to supply domestic water to households. A similar survey of Lake Tarawera found nearly 30 pipes.

Environmental scientist Matt Bloxham hopes the water pipes are no longer in use – but does not know for sure. ”Obviously, just because they’re there doesn’t automatically mean they’re being used.” But he is concerned some people may still be drawing water from the lake for drinking or bathing. “And that is a very risky thing to do,” he adds.

Some residents may be “unrealistically confident” that their water filters are removing toxins – when they’re not. Others may still use lake water because they have done so for decades without any noticeable ill effects. “They underestimate the risks because they forget health impacts are often insidious. Some cyano-toxins can affect your body over time,” Mr Bloxham explains.

Mr Bloxham is also worried that out-of-town holidaymakers may drink the water or use it for showers without realising the risks. “Though publicity has been extensive, there is always that possibility.”

Mr Bloxham says some of the toxicity concentrations recorded during blooms this year have been very high. A bloom on Lake Rotorua in March posted cyano-toxicity concentrations approaching 1000 times World Health Organisation safety standards for drinking water.

Environment Bay of Plenty asked Mourea-based kayaking firm Sunspots to carry out surveys of Lake Rotoiti and Lake Tarawera over summer. Kayakers investigated parts of the lake edges with housing, took GPS coordinates of any pipes they saw, and marked the spot on a topography map. They also took photographs to help identify the sites later.

The information has been given to Rotorua District Council, which will now track down the landowners.

For queries related to health issues please contact Toi te Ora Public Health on (07) 349 3520.