Upper Hodder catchment
The River Hodder rises on White Hill and flows for approximately 23 miles to the River Ribble. The upper reaches of the river feed the large Stocks Reservoir and include Hasgill Beck and Bottoms Beck. This area of the Hodder catchment is characterised by its upland habitats, with extensive areas of upland heath and blanket bog. However, the way this area has been drained historically, has damaged some areas of this rare habitat and surrounding moorlands. Grips or drainage ditches, have increased run-off and increased the amount of sediment being washed into the rivers. Carbonic acid can also be released during periods of heavy rainfall, causing peaks and trough in the pH of the water and affecting fisheries.
Stocks Reservoir impounds the upper reaches of the River Hodder. The abstraction from the reservoir forms an important part of United Utilities' supply of drinking water to many parts of Lancashire. Reservoirs, although providing a vital source of drinking water, can have a negative impact on the biodiversity of an area. For example, the creation of Stocks Reservoir in 1930 has affected the natural flow of the river and created a barrier for migratory river animals such as salmon and trout. The reservoir also causes a blockage in the conveyor belt of sediments or gravel along the riverbed. Further ecosystem disruption occurs along the banks of the river and downstream, reducing wildlife diversity that lives within and alongside the river.
Below Stocks Reservoir, the River Hodder is joined by several tributaries including Barn Gill and Croasdale Brook. Barn Gill is an upland stream, which suffers from many typical upland stream issues. Croasdale Brook starts out on Croasdale Fell, flowing downstream through upland moorland and agricultural land, mainly used for cattle farming. The brook is one of the most important tributaries of the River Hodder, providing consistently good flows of high quality water and habitat. Proactive farming and landowner practices in this area of the catchment contribute to the abundance and diversity of species found in this stretch of the river. However, Croasdale Brook, does represent the upper most limit of invasives species like Himalayan Balsam found within the Hodder catchment, and the site of the old weir in Slaidburn, also causes similar issues to those caused by Stocks Reservoir in terms of causing an obstruction and a barrier to migratory fish passage.
Easington Brook is also a notable tributary of the Hodder. Easington Brook flows from the moor tops separating the Ribble and Hodder catchments. There are several issues facing this stretch of river; upland drainage of the moors, diffuse pollution from agriculture and poor riparian habitat. There are also in-river structures such as bridges and flood gates affecting the natural flow of river and sediments, and also the movement of fish.
The Hodder continues to flow downstream towards Dunsop Bridge and is joined by a quick succession of streams including Foulscale Brook and Birkett Beck. The section of main River Hodder is home to many species, including otters, dippers, kingfishers and Atlantic Salmon which have all been reportedly sighted in this area. Outflows from sewage works, construction of flood banks and the walling of river banks to protect against flooding are probably the main challenges in this area.