Open channel to Big Lagoon/Little Lake (Coopers Lagoon).
Southern Lake Ellesmere near Taumutu to Coopers Lagoon (Big Lagoon/Little Lake) 3 miles to the south; Bray (1875) Scheme No. 4 (see designs/drawings figure).
Description of option
Coopers Lagoon (Big Lagoon/Little Lake) is a small lake with a water level that rises and eventually bursts its banks, between the lagoon and the sea, usually 2-3 times per year. It was therefore proposed that a canal from Taumutu to Coopers Lagoon (Big Lagoon/Little Lake) could be used to pass Lake Ellesmere flows to the sea. It is also likely that this proposal will also require a large sluice gate (100+ feet wide resisting 6-8 feet of water) to prevent rising Big Lagoon water levels from flowing back into Lake Ellesmere.
Opening, closing, and lake level control description
Big Lagoon has a similar level to Lake Ellesmere so long travel distance means required hydraulic grade difficult to achieve. Problem also when Big Lagoon outlet closes; Big Lagoon water level will rise & water will tend to flow back into Lake Ellesmere.
below 50 cumecs
High rates of coastal erosion southwest of Taumutu could compromise any coastal canal structure or increase maintenance costs (e.g. may need dredging due to influx of seawater & gravels).
Likely to need large sluice gate (100+ feet wide resisting 6-8 feet of water) to prevent rising Big Lagoon water levels from flowing back into Lake Ellesmere. 1875 cost: 43,260 pounds for a 3 mile long by 12 ft deep cutting (excl sluice gate cost).
Fish passage benefit rating
Potential running impacts or benefits