Fish Passage on the River Don

South Yorkshire, and in particular Sheffield owes much to the rivers that run through the area. Yet, at one time these rivers were polluted and lifeless. Thankfully, today’s rivers are being revived and transformed, and once again they are full of life; Heron and Otter can be spotted along river corridors, and the rivers provide valuable access to green areas to be enjoyed and celebrated by all.

Throughout the catchment, one of the legacies from our industrial past is the presence of weirs, which were constructed on our rivers to help provide a head of water to factories and mills. Partners from across the catchment have been working together to try and make improvements to ensure that fish are able to move freely along our rivers and make weirs passable by installing fish passes.

Part of the success has been down to a series of fish passes that have allowed a variety of species to ascend otherwise impassable weirs – relics of our industrial past. Fish passes within the Don catchment are in a somewhat unique situation where by there are multiple stakeholders (nine in total) that own weirs – including the fish passes that occupy them. It is also the responsibility of the fish pass owner to maintain these structures to ensure they are operating at maximal capacity all year round, particularly during our busy spring and autumn migration seasons.

The map below shows the overall distribution of barriers along the River Don, and where fish passes have been constructed and are planned. There are also many more weirs on the tributaries of the Don, including the Rivers Dearne and Rother, and further details about these can be found in the Fish passage in the wider Don catchment section below.

A fish pass is any form of conduit, channel, lift, other device or structure which facilitates the free passage of migrating fish over, through or around any dam or other obstruction. Helping fish migrate up and down the river means they can find the best habitat to feed, shelter, spawn and grow.

Larinier - This pass works by slowing the flow and increasing the depth of water through the pass; the angle of the slope for the fish to tackle is also lowered. Larger fish are then able to swim up the pass and make their way up, with smaller fish being able to rest behind the baffles before they jump over the next one. The passes at Brightside and Steelbank have two flights of baffles (see schematic right) with a resting pool in between them that allows fish to recover strength.

Baulk easement - An easement consisting of a baulk or beam usually made of wood or concrete being fixed across the face of the weir sloping downwards to the apron. Where the baulk meets the weir crest a notch is cut. In combination the notch and baulk create a channel of water across and over the weir through which fish can swim. (See schematic right).

Some of the weirs on the River Don have listed status and easements are a less invasive way of helping fish to ascend the weirs and a lower cost option.

Rock ramp – A rock ramp style fish pass consists of a rocky ramp built up to a weir. The ramp is covered in rocks and boulders of differing sizes. It creates a gently sloping ramp up to the weir that fish can simply traverse up.

The map below shows some of the weirs and associated fish passes that are located along the River Don.

Sheffield was founded on five rivers, and the power of these rivers was harnessed during the industrial revolution, helping to create Sheffield’s world-famous steel industry. Water was essential to the economy of the city, and many industries benefited from the River Don. The river was used to transport goods, and water from the river was abstracted to turn waterwheels, supply steam engines, and for use in manufacturing processes such as cooling. All too often, the river was used for dumping trade wastes, and for a long time, a deadly cocktail of chemicals and sewage was pumped into the cities rivers as the industry and population grew.

In the Victorian era part of the River Sheaf was culverted, and channelled into a stone-built subterranean storm drain to divert floodwaters away from key areas in the city. This legendary drain known as  Megatron , runs from Granville Square, following a path under the train station and it emerges to meet with the River Don near to Blonk Street Bridge. More information about the River Sheaf can be found on The Sheaf & Porter Rivers Trust website on the button below:

More recently, major changes were made to Sheffield’s sewers in the late 1970s. At this point, the city’s sewers were struggling to cope with the volume of effluent and the sewers often overflowed into the River Don during rainfall. The solution was to build a tunnel through the rock beneath the existing sewers, and the construction of the Don Valley Intercepting Sewer (DVIS) commenced in 1979. The DVIS is a spine of trunk sewers and branches, which reduce the volumes of combined sewer overflow (CSO) spillage into the Rivers Don, Sheaf and Porter Brook, decrease surcharging (this is when the supply of water to be carried in a sewer is greater than the capacity of the pipes to carry the flow) and also help to lower the risk of flooding from surface water.

The DVIS is so big you could literally have a tea party in it.... as seen below at its opening ceremony in 1982!

Want to find out some more about what happens to sewage and wastewater? Please see the videos below from Yorkshire Water:

There are many issues that contribute to poor fish populations and passage in rivers, and below we will explore some of these issues.

Water quality in the wider Don Catchment is affected by a number of issues including run-off from agricultural and urban areas, septic tanks, sewage and industrial discharges and pollution incidents.

The Water Framework Directive (WFD) provides a comprehensive river basin management planning system to help protect and improve the ecological health of our rivers, lakes, estuaries and coastal and groundwaters.

Waterbodies are sampled by the Environment Agency for a number of different elements to determine ecological and chemical quality. The status classes range from High to Bad for overall and ecological status and Pass to Fail for chemical status.

The three maps below show the overall WFD status, the ecological status and the chemical status:

Weirs are small dams (although some of them are quite big!) that are built across rivers to control the upstream water level. There are many weir structures on the River Don, and these are mainly remnants of our industrial past. Some of these structures are also protected for their historical importance. An example of this is at Sanderson's Weir in Sheffield, which was built in 1825 for Messrs Sanderson (steel manufacturers) on the site of an earlier weir. The weir is Grade ll listed, and the heritage of this structure is important to the local area. When planning a fish passage project, listed building status must be taken into consideration, and any works to alter a listed building in a way that affects its character usually requires listed building consent.

There are multiple stakeholders that own weirs, and the fish passes that occupy them. It is the responsibility of the fish pass owner to maintain these structures to ensure they are operating at maximal capacity all year round, particularly during busy spring and autumn migration seasons.

Rivers are dynamic ecosystems and high flood waters can often cause organic (trees and branches) and non-organic (litter, large debris, sediment and rocky debris) material to partially or fully block the fish pass channels. If properly maintained, in theory, anadromous (sea to river) and potadromous (within river) migrating fish species should be able to reach their appropriate spawning habitats. Maintenance is also important to help with downstream migrants such as smolts (young salmon) and catadromous (river to sea) eels.

Given the diverse organisations that own fish passes, a pilot project on the River Don was set up to ensure involved parties have or are able to access the skills and knowledge needed to properly inspect and maintain their assets. Quarterly meetings are held to discuss maintenance best practise, updates from inspections and future ideas of how fish passes can be adequately maintained going forwards. Also, a collaborative approach to monthly inspections has been organised, whereby the River Stewardship Company, Yorkshire Water and Don Catchment Rivers Trust share the responsibility, meaning individuals are making fewer trips per year and blockages are being recorded.

Sometimes it is not easy to establish the ownership of a weir, and because they can be seen as a liability they have often been excluded from the sales of mill sites. As a result ownership and maintenance responsibilities have frequently been overlooked following organisational change. We often refer to these types of assets has “orphaned weirs”, and this situation can cause delays in the development of a fish passage.

Fish passes are not a perfect solution, so it is always best to remove a barrier where possible! However, it is not always possible to remove barriers, as some perform important functions such as the maintenance of water levels in canals. Where fish passes are required, the type installed can depend upon a number of factors (fish species present, location, heritage status, funding availability, land ownership, access etc). Unfortunately, not all fish species can get up fish passes, and some fish pass types can be ineffective for certain fish species at particular life stages (especially when fish are small and are less powerful swimmers).

Fish passes, also have to potential to cause damage to fish, such as the presence of metal baffles. To help avoid any prospect of injury should fish bump into the baffles, the edges should always be fully rounded. Metal baffles can also have the potential to cause vibrations, which can dissuade fish from entering a pass. To help reduce the risk of this happening, the baffles should be at an appropriate thickness and inspected for wear.

Finally, whilst fish pass designs and technical knowledge for upstream adult migratory salmonids is well advanced, the requirements of other fish species, and for downstream migration of all species is not as advanced and is still being studied to fully understand fish passage needs.

The video below shows the creation of the fish pass at Hadfield Weir in Sheffield.

Here are some before and after fish pass construction photos at Masborough Weir in Rotherham.

Building a new fish pass requires funding and investment, and this is often from a number of different sources, including public, private, and grant funding.

Environment Agency - Rod licence fee income helps to fund important projects, such as fish pass construction where there is a clear demonstrable benefit for the fishery and fishing community. The "Water Environment Investment Fund" (WEIF) can also be used to fund fish passage projects within the Environment Programme.

Many fish passage projects have been awarded funding from bodies such as the National Lottery Heritage Fund, Garfield Weston Foundation, Yorkshire Water, Canal & Rivers Trust and Liz and Terry Bramall Foundation.

Match funding is often required too, and this is when funding is paid in proportion to funding being paid from other sources.

Private businesses have also fully or partly funded fish pass projects on weirs that they own.

Their large appearance – they can be on average around 70cm long but anywhere up to 1.5m in length! Although you can get large brown/sea trout, this sign can at least help you get it down to a salmonid fish.

Fungal spots – salmon that have been in the river for longer may have a number of pale fungal patches on them.

Salmon carcasses – 95% of salmon die after spawning so don’t be worried if you see a dead salmon on the river bank. This is the best thing to find as we can collect a sample for the University of Sheffield to conduct eDNA research on to confirm identification. If you think you’ve seen one of these please contact us immediately.

We don't just carry out fish passage improvements on the River Don, but also in other parts of the River Don catchment, including the River Rother and River Dearne as shown on the maps below:

We'd love to hear from you if you've spotted a Salmon. Details on how to report your sightings can be found on the button below:

Do you have any suggestions to help improve fish passage on the wider River Don catchment? Please feel free to contact us at  hello@dondearnerother.org