Auckland Men Want To Harvest Lakeweed

Press, Volume CIX, Issue 31881, 8 January 1969, Page 20

Auckland Men Want To Harvest Lakeweed

(New Zealand Press Association) AUCKLAND, January 7. Lakeweed in the Rotorua district could be removed witha mechanical harvester at an economic cost, in the opinion of two young Auckland engineers.

The engineers, Messrs H. J. Arthur and L. S. Williams, designed and built the amphibious weed-cut-ing machine that has proved so successful on Western Springs Lake in Auckland. They have now designed a larger machine that would cut and harvest lakeweed at the rate of 10 acres a day. Dr D. Spiller, a scientist formerly with the D.5.1.R., and now secretary of the National Research Advisory Council, who has been controlling the spraying of lakeweed on Lake Rotoiti, has reported to the Lakeweed Control Society that mechanical harvesting is uneconomic.

He estimated it would cost at least 835,000 to buy an imported harvester. Messrs Arthur and Williams disagree.

“It would be ridiculous to import a mechanical harvester when we have the ability to build one here at a fraction

of the cost,” said Mr Williams.

.“There is no problem. If they give us a go we’ll clear the weed—and put it to use as a stock feed. As it is now they are spraying the weed and wasting it.”

Mr Arthur said the Western Springs machine was “only a prototype knocked up to do the job.” It had cost about $BOO. The new machine would cut a swathe 12ft wide to a depth of 10 feet, and would cost about $lO,OOO. An American who yesterday said Lake Rotorua was nothing but an unflushed lavatory was told today by the Mayor of Rotorua that he could “do well to go home and flush his own toilet” before commenting on Lake Rotorua. Commenting on remarks made by Mr T. P. Moellendorff, a sanitation engineer and biologist with the public health department in Seattle, the Mayor of Rotorua (Mr A. M. Linton) said today: “These people that travel round the world and make comments on things that are obvious to local

people, don’t make any contribution to the sum of knowlege at all . . . particularly when their own area Is no better than ours.” Mr Linton said that the problems of Lake Rotorua were being studied by a panel of experts. U.S. MEASURES Mr Moellendorff, in New Zealand on holiday, said it was disgusting to travel 7000 miles to find the same problems he had left behind. In Seattle, the authorities had recently spent sl4m for a sewage treatment plant to protect a lake 22 miles in diameter and about 200 feet deep which had access to the sell and two good-sized rivers flushing it. The plant collected sewage from the entire area, which had a population of about 50,000, and discharged it 35 miles away from the lake. In America if sewage was discharged into water people would not swim in it or even boat or fish in it. “I came to Rotorua for a little fishing because a travel agent in Auckland told me how good the lake was. When I got here I found this lake is nothing but a sewer lagoon,” said Mr Moellendorff. 100,000 GALLONS

About 100,000 gallons of raw sewage was apparently being poured into Lake Rotorua daily. Diseases such as infective hepatitis remained viable for as long as six weeks in water reservoirs.

“You are not only putting sewage into a shallow lake. You are boating, swimming and fishing in it Sewage treatment and recreation such as this can go on, but not in the same environment,” said Mr Moellendorf. He had been horrified to see the way diquat was being used to kill off weed, and even more perturbed when he found that no reseach was being done to investigate the side-effects of its use.

There were many unanswered questions about diquat

“The indiscriminate use of any weedicide or herbicide is premature and endangering to the community,” said Mr Moellendorf. DIFFERING VIEWS Parts of Lake Rotorua well removed from where sewage entered were reasonably safe for swimming, the medical officer of health for Rotorua (Dr E. R. T. Overton) said today. He said the coliform counts taken by the Health Department in Rotorua in 1967 showed that most parts of the lake were within the safety limits recognised by the Pollution Advisory Council.

Dr R. B. Pike, reader in invertebrate biology at Victoria University, Wellington, also visiting Rotorua, was reported as agreeing entirely with Mr Moellendorf. He said he had been appalled at the suggestion of widespread use of the weedkiller diquat to control lakeweed without preliminary biological observations on small enclosed areas, or without full reports from experiments made in America.

Dr D. Spiller, scientific adviser to the Lands Department on the lakeweed problem, said today that it was apparent that neither Mr Moellendorff nor Dr Pike had given their attention to the weed problem for a sufficient time for them to be adequately Informed.