River Calder Improvement Project, Ribble Catchment Weir lowering, habitat enhancement, bank stabilisation, fish pass installation Project location: Ribble Catchment, near Rivers: Pendle Water and the River Calder County: Project start date: June 2010 Project end date: October 2010 Length: 600m (500m at Montford) Cost: approximately £750,000 Upstream/Downstream NGR: SD862398-SD800339

Project Background and Objectives Fig 1: Weir – deconstruction nearing completion The River Calder Improvement Project is an ambitious project led by the Ribble Catchment Conservation Trust (RCCT). While there are existing stetches of natural gravels and riverine features along parts of the river, weirs are a major constraint on fish passage. Pendle Water, upstream of the Calder has fantastic potential for spawning grounds and the project aims to:  ease passage for a number of fish species including trout, to encourage upstream migration.  where possible, enhance riverine habitat. Three projects completed in mid/late 2010 are the focus of this case study. RCCT have also been working with a local school to raise awareness of the river’s importance through its ‘Trout in the Town’ project.

Design

1. Padiham Weir (NGR - SD800339) 10 years in the planning, the Padiham weir project has presented a major challenge. Ideas in this time have included a pool-and-traverse scheme, the installation of a fish pass and even a white water canoe course but due to lack of funds, local opposition and concerns over contaminated sediment, each project came and went. Following surveying, it was decided that the weir could and should be partially deconstructed, and this was carried out in a piecemeal approach to err on the side of caution. A number of small check weirs were installed to ensure the required flow velocity, and a new riffle has been installed. While the site awaits its first flood event, a variety of habitats and flow types can be observed. The works have reduced the weir’s backwater effect on the flow by up to a quarter of a mile.

2. Montford Weir (NGR - SD840369) This project offered a greater opportunity for multiple benefit restoration focusing not only on weir works, but also habitat enhancement, bank stabilisation to combat persistent erosion close to the M65, and park-wide woodland planting. Cobbles from the removal of the structure were left in-stream, offering fish refuge. Fly fisherman have now been seen on site for the first time following works. While there has been erosion on the outer bend upstream, this was anticipated and is being monitored. The backwater effect has been significantly reduced, leaving a diversity of flows. A number of exposed large surface drain pipes which have subsequently fallen into the river are to be removed and reused, and large willow on site is to be cut back and reused as additional bank support. While soft-engineering was the River Restoration Centre Case Study Series This site was last visited by RRC staff on 28th September 2010

Tel/fax: 01234 752979 Email: [email protected] http://www.therrc.co.uk considered on the outside of one wide meander bend, a rock wall will be required to prevent further erosive action, due to the river’s close proximity to the M65 and a sewer. The bed upstream is partly concreted along roughly 150 metres, and this will be demolished to return to a more natural channel. The Forestry Commission has secured funding to plant along the river corridor until 2012, and the existing public access footpath is to meander with the river through the wood. RCCT have been facilitators completing and submitting all the paper work for the landowner and tying to it in with the habitat scheme.

Fig 2: The Montford weir works have led to a transformation of the river channel dynamics

3. (NGR - SD862398) While weir removal was not on option due to the historical, archaeological and public interest in the structure, a Denil fish pass has been constructed, and this will open up 23km of Pendle Water, an upstream tributary. A stone wall, which has been carefully deconstructed to allow workers to access the river, will be rebuilt and a viewing platform may be built to encourage visitor interest in the structure.

Subsequent performance – RRC’s views (2010)

An RRC guided visit of the sites raised the following feedback on the project as a whole:

 Public consultation is extremely important and should be planned and managed effectively. Local people’s livelihoods are very important, and by developing strong relationships and clearly demonstrating the intended benefits, it has been shown that initial anxiety can be overcome.

 Surveying, health and safety and required legislative checks accounted for a large share of the project budget, in one case, up to 75% of the total cost. As such, it is an important consideration.

 The importance of timing the works to avoid coincidence with seasonal requirements of species (and the worst of the weather!) should not be underestimated.

 An experienced contractor in the specific nature of river works (e.g. deconstructing weirs), and preferably previous working relations is worth paying for in projects with a higher risk factor.

 Luckily, while sediment was not contaminated behind Padiham weir as once thought, sediment wash was a major concern. While it varies on a site-by-site basis, by gradually deconstructing the weir, sediment was allowed to naturally settle, in turn creating a diverse mosaic of habitats and flows.

 RCCT have developed a catchment-wide monitoring database to help them prioritise/deliberate over future project work. This is widely recommended and has been achieved through partnerships and committed hard work. the River Restoration Centre Case Study Series This site was last visited by RRC staff on 28th September 2010

Tel/fax: 01234 752979 Email: [email protected] http://www.therrc.co.uk