Last week a lot of effort and head scratching went into making a siphon to take down the level of the lake so that we we will be able to get on with the ‘derivation’ work. Although a relatively simple idea (how to make water go up hill), there were various practical challenges to overcome when trying to establish a siphon that will pass around 22m3/minute of water.
Anyway, Sunday morning saw the third attempt succeed without fracturing the pvc pipe and in 12 hours the lake has steadily lowered down about 30cm which is already about 20,000 tons of water. We had heavy rain all day which didn’t help, but it’s working and should be down enough to get on with the work sometime before the end of the week. We are looking at lowering it by about 1.5m.
The neighbour was interested to see how much it would affect his lake just downstream and when we saw that it was raising his level we opened up his gate in order to let a bit more through.
Water is still pouring through at the 1 major and 2 minor inflows, although you can see in the photos that the top end only has water in the channel now. We are hoping to let this area ‘cure’ and then dig a lot of the mud out and eventually plant some phragmites to help the water quality.