The river Afan

Green Park Weir

Working together to benefit fish migration and port Talbot

Dave Charlesworth Sustainable Fisheries Project Manager at Natural Resources Wales has showed me the rivers behind Swansea Bay. One sight was the green park weir.

Just a short drive out of the Swansea Bay you will find the new and improved Green Park Weir in the Afan river. Dave was one of the initiative-takers to construct a better weir to optimise fish migration routes  in the river Afan. The first step was to bring all the stakeholders together and start a collaboration to work with the stakeholder towards a weir that is optimised for two waterfunctions: fish migration and water extraction.  Part of this project where: the River Afan Water Management Group, Associated British Ports (ABP), Natural Resources Wales (NRW), Tata Steel (UK), Neath Port Talbot County Borough Council, and the Afan Valley Angling Club.

Dave told me that by finding creative perspectives for every stakeholder; everyone was leaning in the same direction. This is why the discussion and negotiations between the different stakeholders where relaxed and informal. An extraordinary achievement because normally big corporations, like this, are working behind a wall of lawyers. This relaxed and informal atmosphere is the true reason of the success that is the Green Park Weir.  

The first step of the new Green Park  Weir was to update the sluices at port Talbot. The sluices where leaking water. This leak was compensated by extracting more water from the Afan river. This meant that during dry times (yes, you do have dry weather in the UK) the tidal part downstream of the river Afan was dried up. You can imagine that stops fish migration. This leak is no repaired. To future bulletproof the continuous flow of water they implemented a new water extraction plan. Using big doors to close of the river in case of extremely dry period but also managing the need to keeping the water levels of port Talbot exact and minimise water loss.

Water management door
Extraction channel


At the edge of the weir is the new fish passage. It is a prime example of what fishpass technologie has to offer. The width of the fish passage is divided in three gentle slopes, each one a bit lower than the previous . This means that between a high and low flow of water a fish always have a path to climb up the fishpass. The flow of water is managed by so called baffles. Upright metal strips in a V shape to slow down the water flowlicity.  

Furthermore, the fish passage is much longer than the weir it self. It even exceeds 20m. This is made so, to compensate the relative steep angle of the weir. Now two 10m strip of baffles at a gentle slope, of no more than 10 degrees, with a resting pool in between ensures that most fish can pass with relative ease. Not only the resting pool is that fish can replenish their strength for the next 10m stretch but is also the prime location to monitor fish. Equipped with a camera we now see an increase of fish swimming up the river Afan.