The Errochty Water is an important spring salmon tributary which joins the River Garry near the House of Bruar. Its upper reaches were dammed as part of the Tummel–Garry hydro scheme and it receives a compensation flow from Errochty Dam. Because the compensation water is drawn from the bottom of the dam, the water temperature is on average lower than it would naturally be in spring and early summer. Furthermore a dense stand of alders has grown up along both banks which creates dense shade along its entire 10 km length. This shading increases the time taken for the water to warm up in summer and, therefore, reinforces the effect of the dam. Dense shading by trees can also suppresses the growth of algae which feeds the invertebrates which in turn feeds the fish.

Initially, as part of the Conservation of Atlantic Salmon in Scotland (CASS) Project – a project funded by the EU LIFE Programme – trees were thinned out along four kilometres of the Errochty by the Tay District Salmon Fisheries Board. The project aimed to reduce shading by over 50% by removing alternate trees and lopping low level branches where appropriate. The felling work was largely conducted by Board staff. A contractor was employed to tidy up the brushwood by chipping.

After the end of the CASS project, by becoming a partner in this project the Tay Foundation was able to facilitate work on another 2km of the Errochty in 2009 by covering the costs of contractors. This was achieved through a generous grant from the Scottish Government / RAFTS. This work meant that two thirds of the length of the Errochty Water have now been completely transformed and conditions should be more productive for juvenile salmon.

Work avoided a section of the river which was identified as important for resting otters.

The Errochty Water had become densely shaded by alders along most of its 8km length. The lack of sunlight in late spring and early summer reduced the amount by which the artificially cool water from Errochty Dam warmed up.

Over a period of two years overshading branches and some of the trees were removed over a 6km length allowing more life-giving sunlight to reach the stream.

The tree thinning work generated vast amounts of brushwood which had to be disposed of by chipping.