Pannett's Culvert

Year proposed

  1908

Status

  Implemented, but failed

Location description

  Taumutu

Description of option

  This timber culvert had a flap at the seaward end to keep shingle out. It was approximately 300+ ft long and 30 ft wide and the top was decked over to keep shingle out and, except for some 60 ft at the 'nose', the culvert was bottomless. The culvert originally incorporated about 100 ft of Dobson's Culvert but this 'nose' was washed away in a heavy storm in 1908. The culvert was used to channel water to promote scouring of gravel during each attempt to open the lake to the sea (for a successful opening total outlet width is scoured to a greater width than culvert). The culvert was gradually destroyed by the action of the sea and by scour during lake openings.

Opening, closing, and lake level control description

  Assists with initiation of mechanical opening. (Requires a greater hydraulic gradient than allowed by current lake operating regime).

Maximum discharge

  above 300 cumecs

Maintenance/Management description

  Failed due to piles being scoured out (Langbein, 1932).

Cost description

  Approx 8,000 pounds to construct at the time (Dalmer, 1970). Mr J. A. Pannett resigned from Ellesmere Lands Drainage Board and (without contract) constructed culvert himself. He was later reimbursed for materials & outwork by Board.

Fish passage benefit rating

  Low

Potential running impacts or benefits

  Designed to channel water and promote scouring of gravel when manual opening of the lake to the sea was attempted. Susceptible to scouring of supporting piles.