Author: Bruce McGlashan, Secretary – River Otter Fisheries Association

Healthy rivers and groundwater are essential to human life. They provide us with water to drink and produce our food. They provide recreational spaces for our health and wellbeing and support our economy - recreational fishing alone creates £1.7 billion of value per year in the UK. But is not just us, healthy rivers provide a variety of important and diverse ecosystems supporting bio-diversity.

Unfortunately, as you will I’m sure be aware from national and local coverage, all is far from well. The recently published report by the Rivers Trust on the state of our rivers highlighted that no single stretch of river in England was in good overall health and just 15% of river stretches achieved good ecological status under the Water Framework Directive (WFD). This status is assessed by looking at a range of measures including chemical water quality and the health of the aquatic plants, fish and invertebrate populations present, or not present, in the river. The River Otter is unfortunately no exception - much of the river is assessed as being in poor ecological health and the remainder is only moderate.

Why is this?  Many of you I suspect will point the finger at South West Water (SWW) and you would be right to do so as their performance and other water companies is in my and many other peoples opinion scandalous. It’s also depressingly predictable given the weak regulatory regime that they’ve been allowed to operate under. 

In the case of the Otter, the problems from SWW assets arise not just from the all too frequently documented discharges of storm sewage from overloaded treatment works and sewer catchments in the Otter Valley but also discharges of treated effluent from some of the sewage treatment works in the catchment that contain high levels of phosphate, a plant nutrient. The problem of storm overflows is catchment wide, but the most frequent discharges are from sewage treatment works and systems serving Honiton, Gittisham, Payhembury, Talaton, East Budleigh/Otterton and Budleigh. Although diluted, the sewage/storm water discharged still contains high levels of suspended solids, which can smother the river bed and aquatic plants, ammonia, which is very toxic to aquatic life and organic matter which when broken down by aquatic microbes can lead to low dissolved oxygen levels in the river. Other pollutants in storm sewage include nitrates, pathogenic bacteria and viruses, toxic chemicals, pharmaceutical and veterinary product residues. 

Excess algal growth in the lower river Otter due to high phosphate levels

However, unpleasant and unacceptable as the current level of sewage pollution of the Otter is, the most significant cause of water quality problems on the river is not the water industry, but the agricultural sector. A sad fact it has in common with many other rivers that flow through predominately rural areas. 

This can be seen by examining data published by the Environment Agency on the reasons why stretches of rivers are currently failing to meet good ecological status. For the Otter, the most common reasons given are poor livestock, soil or nutrient management by the agricultural sector. This is followed by inputs of nutrients from treated and storm sewage. In several cases both causes contribute to the failure of a particular stretch. 

The specific causes of agricultural pollution are many, but include:

• Poor land management of fields, both livestock and arable.
• The run-off of dirty water contaminated with animal and other wastes from farms yards.
• Poor/inadequate storage of farm wastes such as slurry and silage liquor.
• Over application of fertilizers both artificial and natural. 
• Crop spraying with herbicide and pesticides, particularly if done very near to a ditch or stream. 
• Failure of farm infrastructure and equipment leading to pollution incidents involving, farm wastes, chemicals or fuel oil
• Livestock being allowed to access river banks leading to loss of bankside vegetation which in turn allows rapid erosion of river banks as well as habitat loss.

A particular problem in the Otter catchment due to its sandy soils and steep terrain, is the run-off of silt and nutrients from fields planted with maize particularly after the harvest in the Autumn. Once in the river, the silt settles on the bed smothering aquatic plants, invertebrates and fish eggs, whilst plant nutrients such as nitrate and phosphate from run-off stimulate the rapid growth of algae which out compete other aquatic plants and can also reduce dissolved oxygen levels essential for fish and aquatic invertebrates especially at night when algae are no longer photosynthesising.

If the impacts of sewage and agricultural pollution weren’t enough there are a number of other pressures that are currently impacting the Otter’s water quality and ecosystems. These include:

• Over abstraction of groundwater for drinking water supplies particularly around Otterhead Lakes and in the lower Otter Valley. This leads to lower river flows which in turn reduces the dilution of pollutants, as well as warmer water temperatures in the summer.
• Man-made barriers to fish migration, both up and downstream. There are a number of weirs around Honiton and its tributaries including the River Wolf, the Gissage and the River Tale which are of particular concern. 
• Poor habitat due to historic channel straightening and impoundment above weirs as well as disconnection of the flood plain from the rivers channel. These man-made changes to the river can also lead to faster spate flows which in turn cause rapid erosion of the river bank and the scouring of river gravels where invertebrates and fish eggs are found.
• The impacts of climate change, high water temperatures, low flows and flash flooding.
• Toxic chemicals including mercury and the so called forever chemicals which go under the snappy name of polyfluoroalkyl substances (PFAS).  These have hundreds of uses including within nonstick coatings, fabric protectors, firefighting foams and in plastic. Many of these chemicals, which can take hundreds or thousands of years to breakdown, are now found in rivers throughout the UK, usually discharged through residues in treated sewage effluent.  Concern is increasingly being raised about the impact of some pet and livestock veterinary products, particularly the infamous neonicotinoid imidacloprid used in some pet flea and tick treatments, despite these being banned for agricultural use. Not only is this acutely toxic to bees but it’s also similarly very toxic to aquatic invertebrates. These products can enter the water where animals swim in the river or through residues not removed by the sewage treatment process.  
• Polluted run-off from urbans area and roads. Road run off is a particular concern on many rivers, as it can contain oil, diesel and petrol from small spills and leakages as well as particulates from tyre, brake and road surface wear and high salt and sediment levels when roads are de-iced. 
• Plastics, not just the obvious examples such as discarded plastic bottles, crisp packets, cigarette butts and pieces of agricultural plastic, but also microplastics produced for example when plastics breakdown 
• Increasing levels of predation of freshwater and estuarine fish, particularly from cormorants whose numbers have increased greatly in recent years along with changes to their feeding patterns as they move inland to find food.
• Invasive species, particularly Himalayan Balsam which leads to a loss of plant diversity and river bank instability. When the plant dies back, it leaves bare soil that’s easily eroded.
• Poor survival of migratory fish species at sea. Overfishing is one likely cause but not the only one.

A weir on the River Otter below Honiton. This acts as a partial barrier to fish migration. Historic straightening of the river channel and cattle grazing of the river bank has led to increased erosion and poor habitat 

These pressures should also not be considered in isolation as they have a cumulative impact. For example, climate change is predicted to result in reduced summer flows, interspersed with flash flooding as well as increased water temperatures in both summer and winter. These in turn can exacerbate the impacts of pollutants by reducing dilution, dissolved oxygen levels or lead to river temperatures being too high for species, including trout and salmon to survive.

I hope I have not depressed everyone as despite all the pressures the Otter faces it is still home to some fabulous wildlife that lives by it, on it or in it and the river is enjoyed by both locals and visitors alike whether they are fishing, doing a spot of bird watching, playing in it or simply going for a walk beside it. 

It is clear that the public mood has changed and our two groups (the OVA and the team I represent at the River Otter Fisheries Association) are working together with other local groups to prioritise and address these longstanding issues. We are meeting regularly and have agreed to help support and facilitate activities and, where necessary, be a voice for the river by highlighting issues that we feel are not being properly addressed. We will cover the work being undertaken in the next addition of this newsletter as well as highlighting some areas where we believe more needs to be done to protect and improve the river.    

If you are keen to help restore the river Otter to it’s historical excellence, why not volunteer and help our teams in their work?