IMPRACTICABLE

Rotorua Morning Post, Volume 1, Issue 178, 21 March 1932, Page 2

IMPRACTICABLE

. t PEOPOSAL TO CONSTRUCT WBIR TO RAISE LAKE LEVEL MR. COATES'S OPINION Follow'ng the recent representations made by the Rotorua launch-owpers, r; garding the increasing difficulty in r.avigating the Ohau Channel oiying to sand drift, the member for tl]e (ilstriet, Mr. C. II. Clinkard, to whom the representations were made, cpmnuinicated with the Native Ministey, (Sir Apirana Ngata) who duly referred his communication to the Minister for Public Works, (Rh Hon. J. G, Coates) . , In a letter to Sir Apirana on the suhject, Mr Coates states:— The level of Lake Rotorua is regulated largely by the level of Lake Rotoiti, Lake Rotorua maintaining the level of about 1.5 feet above Lake Rotoiti. There are no records in existence of the level of Lake Rotorua, but that of Rotoiti has been obsei'ved over a Iong period of years. The annual va.riation in Rotoiti since 1920 hgs ranged from 0.52 feet in 1922 to 1.60 feet in 1926. From 1921 to 1923 Rotoiti mamtained a low devel, and again during 1930 and 1931 its level dropped to about the same average. These levels are governed by the annual rainfalls, and for the periods

quoted rainfall was decidedly below the average. Under -norma! rainfall, lake "level will come back to normal level. Question of Weir "Coming to the question bf a low weir at the outlet of Lake Rotoiti, it is possible to build such a weir. The estimated cost is between £3,000 and £4,000. It would have to be very carefully built as foundations would not be very good. It would have to be provided with automatic gates tp faciiitate discharge of flood waters. Even then, there would be a certain amount of increased flooding, and a permanently higher lake level on the low margin lands. Due to this cbndition, complications with owners, and legal actions ' by interested people would ccrtainly arise. "A' study of the conditions at Ohau channel connecting Lakes Rotorua and Rotoiti, indicates- that the raising of lake level by a weir would not permanently improve conditipns from the point of yiew of launch traffic. The adverse conditions there, are not so much due to conditions in the channel itself as to'the existance of extensive "sand banks on the Rotorua end of the channel. These sand banks are growing, and if level of Lake Rotorua were raised these banks would at once build up to about the same level 1 in relation to lake level, and conditions- for launching would beeome no better than before. "It will be apparent from the foregoing that the proposal to construct a weir "to regulate the levels of Lakes Rotorua and Rotoiti is unsound and should not be entertained."