By Mermaid Laura Reineke August 2024
Well, with OFWAT’S announcement last week that they’ll be fining 3 of the worst performing water companies, Thames Water being the worst, we (Henley Mermaids) feel that we’ve had one “little win”. However, the measly £104,000,000 fine is just a drop in the poo-filled ocean to the failing water monopoly, and considering they’ve never put more money into infrastructure investment than they’ve paid dividends then I’m not sure what real improvement we can expect.
The problem we have is there is no future proofing in place, the planned upgrades of Sewage Treatment Works (STWs) one of which is Henley, are not enough to cope with capacity, meaning that they will continue to spill raw sewage into our precious river. That, teamed with the fact that there is no planned instillation of tertiary cleaning in place, (A system that cleans off any pathogens, chemicals, recreational drugs & pharma products.) So, with the government commitment to increase housing, and population growth, there is little to no point in starting the job unless it is done properly.
There is however, one very easy fix the government could implement that would improve our waterways for wildlife, and that’s the removal of unused barriers. A river barrier is a structure or obstacle, either natural or man-made. With only three years to go before the 2027 deadline for achieving good ecological status in English rivers, it is worrying that still nothing has been implemented. The regulations have been promised since 2009, but, here we are in 2024 with still no regulations materialising.
For hundreds of years humans have been manipulating and controlling our waterways for their own benefit, profoundly altering the behaviour of many rivers, and one of these modifications is the use of barriers. We know all about this in Henley, with a series of locks and weirs. But there are 7 types of barrier in this country: Culvert, Weir, Sluice, Dam (the oldest known dam is Bronze Age as early as 3000 BC), Ford, Ramp, and “other”. They can have many purposes including industrial, agricultural, infrastructure, flood defence, land reclamation, environmental management or aesthetic. Today, it is thought globally up to 63% of all rivers over 1000km in length are no longer free flowing. Manmade barriers make up 75.28% of the total, and out of that total weirs take well over half. There are also non-physical barriers, where there is a change in chemical water quality (both naturally when moving fresh water into the sea, and unnaturally, like pollution events) or a thermal barrier, where there is a change in temperature. And natural barriers like waterfalls, which make up 98.2% of the natural barriers found.
There are both positive and negative effects on the environment when it comes to barriers, for instance hydropower reduces carbon emissions. In reality some barriers are needed, and we would need to find another in-river flood protection to protect the one in six properties that are at risk of flooding. But first and foremost our rivers are there for wildlife and need rewiggling (yes, a real word) they need natural flood plains, creating wetlands that absorb floodwaters, natural bends and curves which can slow down water flow, reduce erosion.
The negative effects of barriers are that they can limit the number of fish being able to move between habitat types, particularly diadromous fish (migratory), and in many cases prevent fish migration and movement altogether. Barriers create bottlenecks, even interventions at barriers such as fish passes will limit the number of fish being able to successfully traverse the obstacle – they don’t provide 100% pass ability. There may be a fish pass on one weir and not on the next, creating yet another problem. River barriers have been identified as one of the leading causes of global declines in many migratory fish species. Atlantic Salmon in particular have been affected by habitat fragmentation caused by barriers, and this has seen them moved onto the ICUN’s ‘red list’ of threatened species. Aquatic flora, much like animals need to be able to travel freely along waterways, in order to successfully reproduce and colonise. Studies have shown that river barriers can effect plant colonisation directly.
Fish wait for ideal flow conditions to be able to successfully traverse barriers, they need to find a successful route through barriers, or expend more energy than should be needed because of the barriers. This can affect the timing of their spawning and lead to lower chances of egg survival, this, teamed with warmer climatic and hydrological conditions, they are on the front line of our biodiversity crisis.
While waiting for these ideal conditions at a barrier, fish gather in numbers, I won’t say large numbers as the decline in Atlantic salmon alone saw a decline of 23% since 2006, and is predicted to decline a further 50-80% between 2010 and 2025. Where they gather, they are sitting ducks for predators, being picked-off like a canapé tray of delicacies for the birds of prey and other predators.
· There are at least 62,235 barriers officially recorded in the UK – this is likely to be far more.
· It is estimated that ½ of these aren’t in use, and could be removed.
· 0.4% of UK barriers have a fish or eel pass.
· There are 0.75 barriers per 1km of river in the UK.
In short, river barriers, both natural and man-made, have significant impacts on the environment, wildlife and water quality.
Our rivers need rewilding and with biodiversity declining at a rate faster than the last mass extinction 68m years ago, and all rivers in poor ecological health, we need to change our outlook, and leave a lasting legacy rather than our disconnection with nature, and specifically our blue spaces.
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