Stour

Stour | Essex Rivers Hub

The Stour Operational Catchment

There are 21 water bodies in this operational catchment, multiple small rivers and brooks lead into the Stour Estuary. The four main water bodies are named after the four main bodies of water, although do contain other named bodies of water: Stutton Brook, Holbrook, Wrabness Brook and Ramsey River.

The River Stour is 47 miles long, it rises to the west of Great Bradley in Cambridgeshire and for the most part forms the county boundary between Suffolk and Essex. From its source it flows east to Haverhill, Clare, Sudbury, Nayland, Stratford St Mary and Dedham, becoming tidal just before Manningtree and joining the North Sea at Harwich. The Dedham Vale Area of Outstanding Natural Beauty (AONB) stretches upstream from Manningtree to within 1 mile of Bures. The Stour is navigable from Cattawade to Brundon Mill. The Stour valley retains a rural landscape with rich diversity of wildlife and habitat as painted by the artists Constable and Gainsborough.

This catchment consists of the Upper River Stour, which is split into 2 parts (Upper Stour and Upper Stour upstream of Lamarsh), Chad Brook, Lower Glem, Upper Glem, Chilton Brook, Belchamp Brook, Stour Brook and Bumpstead Brook. Upper Stour and Upper Stour upstream of Lamarsh are the main water bodies within the catchment and the others are tributaries that flow into the Upper Stour apart from the upper Glem which flows into the Lower Glem.

This catchment also includes the Lower River Stour (split into 2 sections; Lower River Stour downstream of Lamarsh and Lower River Stour), River Box, Lavenham Brook, River Brett, Old River Brett and Bildeston Brook. Lavenham Brook flows into River Brett and the River Brett flows into Lower River Stour. Both Old River Brett and Bildeston Brook flow into the Lavenham Brook/River Brett area and the River Box is another tributary of the River Stour.

The Stour Estuary is a designated Ramsar Wetland of International Importance, Special Protection Area (SPA) and Site of Special Scientific Interest (SSSI). The estuary consists of extensive mudflats, low cliffs, saltmarsh, and areas of vegetated shingle on the lower river reaches. The site supports internationally and nationally important numbers of numerous species of wintering wildfowl and waders. Several nationally scarce plants and invertebrates occur.

Stour Gallery

Pressures

The pressures for this waterbody are divided into categories: Diffuse Pollution, Fish Passage, Flow, Invasive Species, Physical Modification, and Point Source . Please click here to view these pressure descriptions in more detail.

Upper River Crouch

Diffuse Pollution

Runoff from agricultural land and urban areas have contributed to this waterbody having problems with phosphate, dissolved oxygen and ammonia.

Point Source

There are multiple point sources of pollution along this waterbody which contribute to it having problems with phosphate, dissolved oxygen and ammonia. These issues come from trade discharges and misconnections. There are also known consented overflows on the sewerage network.

River Crouch – Cray's Hill to Wickford

Diffuse Pollution

Runoff from agricultural land and urban areas have contributed to this waterbody having problems with phosphate.

Invasive Species

Japanese Knotweed has been most recently recorded on this water body in 2010. This plant not only shades out native plants, but also causes serious damage to buildings.

American Mink have been most recently recorded on this water body in 2008 . American Mink cause a wide range of problems on a river, including playing a large part in the local extinction of many natural species such as water voles and kingfishers.

Point Source

Phosphate levels within this waterbody are considered to be too high and therefore have a ‘bad’ classification. The point source inputs need to be identified although there is a sewage treatment works that discharges into this waterbody.

River Crouch Downstream of Wickford

Diffuse Pollution

The diffuse agricultural pollution entering the river within this waterbody is described as ‘chronic’, there has also been diffuse pollution identified from urban sources

Invasive Species

Signal Crayfish have been most recently recorded on this water body in 2009. Signal Crayfish cause changes to the natural bankside habitat and also out-compete our native crayfish. They are fierce predators and can completely change fish and invertebrate communities so that they are no longer in their natural state.

Point Source

Phosphate levels within this waterbody are considered to be too high and therefore have a ‘poor’ classification. The point source inputs need to be identified although there is a sewage treatment works that discharges into this waterbody.

Rettendon Brook

Diffuse Pollution

There is no data due to a lack of water testing and investigation within this waterbody. This lack of data may be due to the small size of the waterbody and the influence of the tide, meaning that it may be better assessed with transitional waterbodies.
Fish passage
There is no data due to a lack of biological monitoring within this waterbody. This lack of data may be due to the small size of the waterbody and the influence of the tide, meaning that it may be better assessed with transitional waterbodies.

Invasive Species

There is no data due to a lack of biological monitoring within this waterbody. This lack of data may be due to the small size of the waterbody and the influence of the tide, meaning that it may be better assessed with transitional waterbodies.

Physical Modification

There is no data due to a lack of monitoring within this waterbody. This lack of data may be due to the small size of the waterbody and the influence of the tide, meaning that it may be better assessed with transitional waterbodies.

Point Source

There is no data due to a lack of water testing and investigation within this waterbody. This lack of data may be due to the small size of the waterbody and the influence of the tide, meaning that it may be better assessed with transitional waterbodies.

Prittle Brook

Diffuse Pollution

The diffuse agricultural pollution entering the river within this waterbody is contributing to the higher levels of phosphate detected here. Urbanisation in the land surrounding the river has also increased the amount of urban run-off.

Invasive Species

Japanese Knotweed has been most recently recorded on this water body in 2011 . This plant not only shades out native plants, but also causes serious damage to buildings.

Physical Modification

This river has been historically modified, measures were put in place, but these were not taken forward.
Point source
Phosphate levels within this waterbody are considered to be too high and therefore have a ‘poor’ classification and ammonia levels which are ‘moderate. The point source inputs need to be identified although there is a sewage treatment works that discharges into this waterbody.

Eastwood Brook

Physical Modification

There is no data due to a lack of monitoring within this waterbody.

Point Source

Phosphate levels within this waterbody are considered to be too high and therefore have a ‘bad’ classification. The point source inputs need to be identified although there is a sewage treatment works that discharges into this waterbody. Other sources have also been identified such as local industrial estates and business. Invertebrates are also classed as ‘moderate’ which may be because of these point source pollutants.

Nobles Green Ditch

Physical Modification

There is no data due to a lack of monitoring within this waterbody.

Point Source

Phosphate levels within this waterbody are considered to be too high and therefore have a ‘bad’ classification. The point source inputs need to be identified although there is a sewage treatment works that discharges into this waterbody. Other sources have also been identified such as local industrial estates and business. Invertebrates are also classed as ‘moderate’ which may be because of these point source pollutants.

River Roach

Physical Modification

There is no data due to a lack of monitoring within this waterbody.

Point Source

Phosphate levels within this waterbody are considered to be too high and therefore have a ‘bad’ classification. The point source inputs need to be identified although there is a sewage treatment works that discharges into this waterbody. Other sources have also been identified such as local industrial estates and business. Invertebrates are also classed as ‘moderate’ which may be because of these point source pollutants.

Catchments

Completed Projects

River Brett Restoration

View Project

Bures Mill Eel Pass

View Project

Pressures

The topics below represent the pressures that many waterbodies in the Combined Essex catchment face. They have been divided into six main categories, but it is quite often that these categories can overlap as pressures relate to each other.

Diffuse Pollution

Diffuse pollution occurs as water moves across the land or through the ground and picks pollutants. These pollutants can come from a variety of places, including urban and field run off. The pollutants that enter the river can range from sediment to toxins to excess nutrients, meaning that diffuse pollution can cause a whole range of different issues. The variety in these pressure groups means that it is something that can be quite difficult to tackle. It requires groups of people, business and stakeholders to work together in order to solve this problem.

Fish Passage

Fish should be able to travel up and down a river freely, allowing them to move and breed in the most suitable habitats for them. It is important that fish populations do not become isolated, as this makes them more susceptible to disease and puts pressure on their survival. Unfortunately, there are often many barriers along rivers that prevent fish from being able to migrate up and down stream. Where barriers have been identified, they will be seen as a ‘pressure’ on a waterbody. Thankfully, there are many solutions now that can be put in place to aid fish passage, even over large barriers.

Flow

The flow in a river can vary greatly throughout the year as rainfall and run off can have an effect. This is a natural process. It is when flow is impacted by non-natural processes that it can cause problems. Sometimes, water can be intercepted or removed from a system; this will reduce the flow, therefore changing the habitat conditions. Some species are happy in high energy rivers. This means that when flow is reduced, these species will no longer survive. The opposite of this can occur when excess water is entering a river, for example through increased runoff. Low energy systems then become high energy and displace the species that live there.

Invasive Species

A species that is not meant to be found in a particular area is known as an invasive species. Invasive species can be from a different habitat or a different country altogether. Most of the invasive species that we find on our rivers have come from other countries – plants that people have imported for their gardens or animals that have been released for food or by animal rights activists. Control of invasive species requires a lot of time and effort. We are fortunate that we do have a range of methods to manage most of the invasive species that cause havoc on our rivers, but there are still some which we are still struggling to control.

Physical Modification

Many of our rivers have been heavily modified over the years as rivers have been used for a wide range of purposes. Physical modification is one of the biggest factors that causes our rivers to be unhealthy. The issues that it can cause range from reducing habitat, preventing migration of mobile species, and even have an effect on the water quality. Where structures and modifications are no longer in use or necessary, they should be removed to allow the river to regain its natural state. Unfortunately, this action is not always taken which means that many of our rivers are over straightened and contain redundant structures. It is possible to return a lot of our rivers to their natural state, through one off projects, but in other cases it is not possible as the river has been changed to protect assets or manage flooding. It is recognised that some modifications cannot be removed without having severe negative impacts both socially and economically.

Point Source

This is pollution that comes from a single identifiable source. The pollution entering the river could include a whole range of pollutants. Some point source pollution is known about and licences, for example sewage treatment works. Other sources are not licensed, and therefore work needs to be done with landowners to fix the problems that are allowing the pollution to enter the river. Point source pollution is more easily controlled than diffuse pollution as it often only takes one management approach to solve the issue.