More off-line lakes

I have been an advocate of off-line storage for water supplies for many years.

When Te Marua water treatment was built two off-line storage lakes were provided to cope with demand for water during dry spells or when water was not suitable for treatment due to severe wet weather conditions.

Dams were not considered desirable or practicable for a number of reasons, including that the judicious withdrawal of river water to fill storage lakes ensures good quality water is always available for treatment, although algal blooms could occasionally be a problem.

Wellington needs to get on with its next off line storage project at Kaitoke and other authorities should give serious consideration to similar projects where practicable.

Auckland is at present experiencing major wet weather sediment problems with its water supplies in the Hunua Ranges, where water is drawn from dams.

Perhaps ironically, I ran the soils laboratory during the construction of the Hunua Dam project in the early 1950s when offline storage would never have been contemplated and climate changes effects were never heard of. How views can change over time. KEITH DAVIS Elderslea