Water engineers scale down noise for salmon

Noise reduction measures are being implemented in a bid make sure the King of Fish hardly hear a murmur when a 6 million drinking water supply scheme is switched on to bring fresh water to more than 700 homes in Wester Ross.

The scheme will involve taking water from the River Ewe where it leaves Loch Maree where one local landowner recently invested heavily to increase salmon stock levels on the three-kilometre long river. The main pipe, which will draw water from the river, will be on one of the prime fishing pools.

Scottish Water has sought the advice of Richard Horsfield, an international expert in fish behaviour, to ensure the salmon are virtually undisturbed once the scheme gets under way.

The measures being put in place include placing a series of rubber couplings on sections of the pipe to dampen any noise or vibration caused by the water extraction pump system. And the water intake on the Ewe is being designed to ensure that the velocity of the water extraction is low enough to ensure that juvenile fish won't be sucked into the system. A mesh across the front of the intake will also be small enough to prevent fish eggs from being sucked in.

Horsfield, a director of Turnpenny Horsfield Associates, based in Southampton, said: "Salmon are sensitive to noise but they pick up vibration rather than sound pressure. And high volumes can be potentially damaging to fish. But at the River Ewe scheme rubber couplings will be fitted between sections of the pipe to ensure the sound decays as it passes down the system and to reduce the sound that is emitted into the environment. The noise will be very low. It is very unlikely that the fish are going to respond to the level of sound."

Jason Rose, a spokesman for Scottish Water, said: "We've worked hard at Loch Maree to ensure we can supply the communities with the drinking water they need while keeping the other local residents - the sea trout and salmon - happy."