Pollution and The River Dart

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River Dart from the Air

The following  is an extract from information found on the South Devon AONB website.

Pollution in the Dart

The Dart estuary has a large catchment area with a 'flashy' substrate which means that almost as soon as rain falls on the land its effects are seen in the estuary. Unlike rivers with large flood plains there is no time for pollutants or excess nutrients to be absorbed before they turn up in the river. Pollutants can make their way quickly into the water and be highly toxic killing wildlife within the Dart. They can also reduce the oxygen content and water quality of the estuary potentially leading to ‘anoxic dead zones’. It is important that we understand how our actions can affect the estuary and what we can do to prevent them.

• Dispose of all your waste carefully, recycling as much as possible
• Try using low phosphate environmentally degradable cleaning products
• When changing oil and refuelling cars be careful not to spill any as it will end up in the estuary downstream

Pollution or Natural?

It can be difficult to distinguish between pollution (pictured above) and events which occur naturally in the estuarine system. On an incoming tide you will often be able to see a golden brown froth occurring on the waters surface, which can easily be mistaken for pollution....these are in fact diatoms.

Diatoms are phytoplankton which live in the water column and on the surface of the mud in estuaries. These tiny plants use sunlight and nutrients in the water and mud to grow and reproduce. On an incoming tide many of the diatoms are lifted from the surface of the mud and form the golden brown frothy 'scum' on the surface of the water, a nutritious meal for grey mullet as they follow the water in.  

One good tip for identifying a pollution incident is to keep an eye out for any household waste such as tissues or cotton buds within the scum. If you do suspect you have seen pollution please contact the Environment Agency's 24hr Incident Hotline on 0800 807060

For further information please view the Environment Agency's Algae or Sewage leaflet.

Algal Blooms

The Dart estuary teems with life, much of it microscopic and most of it harmless. However given the right conditions the usually harmless phytoplankton can grow in such large numbers that they block sunlight from the water and can become toxic to humans and animals in the estuary.

These algal blooms have been occurring more frequently worldwide due to human input of nutrients into the water. In the estuary these excess nutrients can come from runoff from farming but more recently it has been through what we as householders pour down the drain.

To help reduce these algal blooms we need to reduce the amount of cleaning products we use. In addition, try using cleaning products that are phosphate free and environmentally biodegradable.

Marine Litter

Marine litter is an ongoing problem. It can be poor aesthetically, and hazardous to wildlife. The litter found on the South Devon beaches comes from a variety of sources including being discarded at sea and litter left by people utilising the beaches and surrounding areas. The Marine Conservation Society is a lead organisation in tackling this problem and beach clean up events are regularly conducted as part of the Marine Conservation Society's adopt-a-beach campaign.