AFTER almost 40 years when no new pump storage hydro (PSH) schemes were developed in Britain, there is now a gold rush by developers seeking new sites.

The switch from fossil fuels to renewables, which tend to produce power more intermittently, means more long-duration energy storage is required. Portrayed by some as a novel solution to generation intermittency, this mature form of energy storage is now finding a new, global, lease of life.

Climate change is the greatest threat to our native biodiversity, including wild salmon, and we are fully supportive of the de-carbonisation of the national grid. However, while we are not against PSH per se, we strongly believe that such projects should be located where the environmental risks are lowest.

What is PSH? Low-demand (inexpensive) electricity is used to pump water uphill into an upper reservoir, often overnight. When demand for energy increases, and the price rises, the valves are opened and the stored water flows back down generating valuable electricity this time.

Daily movements in the spot price for electricity can be extreme, and even though it requires more energy to pump water uphill, substantial economic gains await.

Why are we, a local salmon fishery board, so concerned that we are campaigning against the proliferation of pump storage on Loch Ness?

Loch Ness is in demand for PSH schemes. Foyers PSH was commissioned in 1974; the Red John PSH scheme was granted planning permission in 2021; and, in November 2023, the planning application for the proposed Loch Kemp scheme was submitted.

The proposed Kemp scheme has four times the capacity of Foyers or Red John. Of particular concern is the cumulative impact of these multiple schemes on the ecology of Loch Ness.

Our concerns about PSH relate to its potential impact on wild salmon smolts as they leave their natal rivers, and head seawards, migrating through lochs, including Loch Ness. This potential impact is a huge knowledge gap, as are the potential for impacts on the temperature and hydrology of Loch Ness.

Other concerns include the impact that large and rapid water level changes will have on shoreline ecology and River Ness flows; and wider ecosystem impacts.

Atlantic salmon are in decline, across their range, with Britain’s population recently classed as endangered by the IUCN. This decline affects more than just salmon anglers. Atlantic salmon, that iconic species, are a fundamental part of the ecology of the Highlands.

Chanonry Point, a spectacular natural narrowing of the Moray Firth close to Inverness, is the scene of the greatest wildlife spectacle in the Highlands.

Here bottle-nosed dolphins patrol the point, ambushing and eating salmon as they return to the River Ness. There can be few more obvious examples of an ecosystem in action than this link between river and loch and the sea.

Of course, this is Loch Ness, so there are wider concerns aside from ecology. PSH is just one sector and many other sectors are reliant on water levels in Loch Ness, including commercial cruise boat operators, recreational craft, Caledonian Canal traffic, rescue boats etc.

There is a legally agreed minimum loch level between Foyers PSH and Scottish Canals to ensure safe navigation. But if Loch Kemp is approved Loch Ness will be at minimum levels much more often, almost daily during the summer, affecting all other users of the loch.

Quite what the most famous inhabitant of the great loch will make of the cumulative impact on the natural, seasonally driven hydrology of the loch, or its famed stable temperature regime remains to be seen.

In that regard we are all in the same boat, the research simply hasn’t been done. Perhaps this is understandable given the lack of interest in this technology in recent decades.

We are actively campaigning against any further PSH schemes on Loch Ness until further research is completed and the PSH sector can prove that its activities are as environmentally benign as claimed.

In the meantime, we are asking the Scottish government to produce clear guidance to ensure that the sector only develops in the most appropriate and least damaging locations.

Brian Shaw is director of the Ness District Salmon Fishery Board — a petition can be signed at www.bit.ly/NessHydro.