LAKE ELLESMERE OPENED

Press, Volume LXXXIIi, Issue 25214, 19 June 1947, Page 3

LAKE ELLESMERE OPENED

CUT MADE QUICKLY BY CATCHMENT PLANT

THREE YEARS’ TRIAL AND SURVEY BEGUN

With three heavy bulldozers working together and a fourth being, brought from Dunsandel in case it should he needed, a new phase in the work of controlling the level of Lake Ellesmere was begun by the North Canterbury Catchment Board at noon yesterday.

It was the first time the periodical letting out of the lake had been undertaken by the board since it took over the functions of the Ellesmere Land Drainage Board. Bulldozers have been used to cut an outlet through the spit before, but not so many; the result is an impressive saving in time and cost, with greater certainty of overcoming the hazards of tide and weather. By 8.30 p.m. the lake waters were running through a channel already 20 feet wide and about 160 yards long into a sea almost as calm as the lake. Previously the work has taken upwards of two days. Asked about the cost. Mr H. W. Harris, the board’s chief engineer, who stayed on the job till the cut was complete, said that it would be about £l5O. In the past it has cost as much as £ 900 to let out the lake. The phase of operations begun by the board is to last three years, after which the Government is to consider again the merits of the permanent outlet' proposal—costing perhaps £soo.ooo—in the light of experience with the periodical cuts. There is more in the work than the cuts themselves. Systematic observations of lake levels and depths in the neighbourhood of the cuts, at Taumutu. the extent of land affected, and the states of wind and tide are to be made over the whole three-year period. Then it will be possible to compare the present methods with the larger project in terms both of cost and effectiveness. Soundings Taken For yesterday’s cut. careful soundings had been taken, so as to make the shortest run for the water from the deepest part of the lake. These soundings, said Mr Harris, were on record and would be repeated, so that as the lake was let out from time to time a regular channel might be developed to the site of the cuts. A fairly calm sea. a northerly wind, and a rising tide are the ideal conditions for beginning the job. The northerly wind, banking up the waters at the Taumutu end of the lake, had dropped yesterday afternoon, but tide and sea were favourable. The engineers. watching the work proceeding from the crest of the beach, had received their weather report from the Meteorological Office, promising a light southerly to-day.

Water almost covered the tracks of the bulldozers as they lurched into the middle of the cut—a bulldozer should not work in more than two feet of water —before ploughing back up the 20ft high slopes they had thrown up at either side. In five hours they hao. dug the channel for 100 yards or more, to the highest part of the beach on the seaward side. The depth of the cut from the level of the beach is about nine feet. How long the present cut will last is a matter of interest to the board. To lessen any filling up caused by the sides sliding in. the bulldozers have pushed the mounds of spoil, further back to either side than on previous occasions. A heavy sea can block the cut and rebuild the bank in a mattei of hours; but in good weather a cut has been known to last as long as three months. For the moment the critical stage is the next high tide, about six o’clock this morning.

The Catchment Board’s responsibility is clearly defined. It is bound to let the lake out, if possible, when* the gauge at the Kaituna end shows 2ft 9in in summer or 3ft in winter. The board may. for experimental purposes and in consultation with the Soil Conservation and Rivers Control Council, let the lake out when it is below those levels.