Yorkshire Water, the Environment Agency and British Canoeing are working together to understand the environmental impact of various activities on the River Washburn downstream of Thruscross reservoir, as required by the Water Framework Directive.
The river levels fluctuate between periods of low flow due to the presence of the reservoir and very high flows from releases for canoe events and seasonal overtopping. There are also two weirs that restrict fish movement and these river conditions make it difficult for fish to find suitable habitat to lay eggs and can lead to them being washed downstream or stranded in pools.
In collaboration with the University of Hull International Fisheries Institute, we are using a fish tagging technique to monitor the movement of brown trout along the river.
In 2016 Yorkshire Water will trial a new flow release from the reservoir to guarantee a flow during dry periods, install automated valves to allow a more gradual release of water for canoe events and investigate options to help fish move over the weirs. The new valves will be tested over several canoe events, starting in the spring.
We are working with British Canoeing to understand how the number, timing and duration of events can be optimised to best support the environment whilst ensuring the long term sustainability of canoeing in the River Washburn. To support this we are asking paddlers to pre-register helping us to plan and manage the releases and justify the substantial amount of water used to support the canoeing events.
You can find more detailed information below about these proposals and the background information to them.
Thruscross to Fewston Reservoirs
The source of the Washburn is in the West Nidderdale, Barden and Blubberhouses Moors Site of Special Scientific Interest (SSSI) and the North Pennine Moors Special Area of Conservation (SAC) and Special Protection Area (SPA). The River Washburn starts on Pock Stones Moor and flows with tributary Capelshaw Beck directly into Thruscross Reservoir. Below the dam, the river runs for approximately 3km before entering Fewston and the adjacent Swinsty Reservoir.
Thruscross was constructed in 1966 and is the top of four reservoirs in the Washburn Valley. It is used for storage along with Fewston and to regulate the amount of water in Swinsty reservoir, the only supply reservoir in the chain. The bottom reservoir, Lindley Wood supplies compensation to the river downstream.
The Environment Agency’s Heavily Modified Waterbody investigation confirmed a probable impact (>80% deviation from natural) on flow in the section of river between Thruscross and Fewston reservoir. Further biological investigation confirmed that fish are at ‘poor’ status under the WFD with lower than expected densities of Brown Trout and the absence of species such as Bullhead. It concluded that the flow impact upon fish was complicated by prolonged periods of low flow and the high energy flows released for canoeing events.
The work undertaken during 2015 recognised that at this site introducing just a ‘low flow’ element to the flow regime is unlikely to fully support river ecology and the EA and YW will continue to work alongside the Washburn Management Committee and British Canoeing to improve the management of the canoe releases and investigate whether targeted river restoration work is required to improve fish habitat. Therefore introducing an appropriate baseline flow regime alongside the wider catchment improvements are critical for the River Washburn to move towards the target of meeting Good Ecological Potential.
Targeted ecological monitoring will be used to help determine whether the new compensation flow regime is appropriate.