LAKE PUPUKE.

Auckland Star, Volume LXXI, Issue 309, 30 December 1940, Page 5

LAKE PUPUKE.

CONNECTION WITH SEA

FLOW OF SALT WATER. ———— "Aquarius" writes:— | In reply to E E Adam*, regarding jthe subterranean channel between Lain | Pupuke and the sea: The fresh water | that could be dipped up half a mile from I Rangitoto came up through a fissure | from that inland. The other fresh water flow that he mentions. va» connected j with the overflow from Lake Pupuke. i This flow escapes from a fissure at | about half-tide in Thorne's Bay. In ! 1912 the flow from this fissure was 150,000 gallons per day, jrood fresh water. | To-day there is a fair flow from this | figure, but it is now pure salt sea I water. This flow is continuous irrespee- | tive of the tides. This cancels the theory ■of a subterranean channel between the jsea and Lake Pupuke. This flow of j water was fresh so long as. the level of jthe lake was above mean high water, ! a nd the lake had an overflow, but iha 1 level of Lake Pupuke is now about seven j feet below mean high water. I As regards salt water finding its way I into the lake, at present there is a seep- | age. though not enough to cause alarm, but it would be dangerous to pump tha surface of the lake to a lower level. Re Mr. Adams' tunnel scheme: The lake is an old crater surrounded mostly by basalt and scoria. The contact j bet ween the ba>alt and the sedimentary ! rocks contorms to the shape of the lake with a dip on al] sides towards the lake. At the point of contact there is the jib-ual com ract ion. caused bv co.ilinjr, 1 which lias cau-ed the two rocks to >hrirk from each other, result ins in the i format ion of cavitic- alonjr the point of contact. All water falling within the lake water-lied now finding its wav into the lake. So what {rood would it do to drive a tunnel from the lake edga to the contact? i There is only one way to remedy the j present unsatisfactory water supply, (and that is city water, and delay will te-daoserom.