Freshwater Treasures of the Thames

Thames Water LogoHLF useWhat remains of the Thames Water region heritage that we should value?

Scattered up and down the rivers, and across the rest of the landscape are the freshwater treasures which remind us of the glory of clean and natural freshwater habitats. These are the places through Thames Water for Wildlife that we are trying to project – and if we can expand the ranges of by making new habitats or cleaning up the polluted ones.

Here are ten examples of places that we need to look after specially:

1. Otmoor rifle range ponds and pools

This a one of our flagship sites, containing some of the best ponds for wildlife. The ponds and ancient river channels of Otmoor show us something of what grazed wet meadows and their freshwaters would once have been like up and down the Thames Valley. Separated from the surrounding intensive farmland by a kilometre of low intensity grassland, at the heart of this area are the Fowl’s Pill (pool) and the New Pill, constructed as one of Freshwater Habitats Trust’s earliest experiments in pond creation. These sites are now showcases of ‘what ponds should be like’ when they are properly protected from pollution. With a rich variety of smaller animals and endangered water plants including Water-violet and Lesser Water-plantain. On the surrounding grasslands Snipe, redshank and Curlew may be seen, benefiting from the restoration work done to create the RSPB Otmoor reserve, now the supporting the largest inland concentration of breeding waders in the Thames.

Please note the site is an active military site. Access is not permitted when the red flags are flying. A public footpath crosses the site.


Otmoor with Water Violet in full bloom.

2. The Thames at Goring

Despite the boats, the locks and high levels of nutrients, the upper Thames is still home to several special animals, amongst which is the Club-tailed Dragonfly which is found only in a handful of large southern rivers. In later April the larvae emerge from the water on vertical rivers banks, water plants and moorings to take wing and head to the nearby woods for mating. Females then return to the river to lay their eggs in the shallow gravelly margins of the river where the larvae then spend 2 to 3 years growing to maturity. Club-tailed dragonflies are amongst the first to emerge in the year.

3. The River Loddon near Stratfield Saye

The River Loddon is a medium sized river with a catchment of 680 km square in Surrey, Hampshire and Berkshire. Although affected by pollution, the River Loddon is still able to support the Red Data Book Loddon Pondweed and has an excellent variety of invertebrates, including two species of pea mussels which are found in few other rivers. However, because of the pollution it is classed as being at ‘Moderate’ status under the five point Water Framework Directive classification (High, Good, Moderate, Poor, Bad).

4. Little Wittenham

This a one of our flagship sites, containing some of the best ponds for wildlife. The ponds at Little Wittenham are protected because they and the surrounding woodlands provide habitat for a large population of Great Crested Newts. Although Great Crested Newts are found all across the Thames, outside of the built up urban and suburban areas, the population at Little Wittenham was at one time one of the largest in the Thames. Management work is currently in progress to help populations return to their previous levels.

GCN eft

5. Cock Marsh

This a one of our flagship sites, containing some of the best ponds for wildlife. Cock Marsh is a small area of river floodplain meadow near Maidenhead looked after by the National Trust. It is special because the ponds are still in good enough condition to support some of our most endangered water plants including the Brown Sedge, Water-violet and Tubular Water-dropwort. The ponds depend on gentle grazing by cattle, and the light shade provided by overhanging willows.

6. Bramshill Forest

This a one of our flagship sites, containing some of the best ponds for wildlife. Bramshill Forest is a large area of acid woodland that was planted on heathland and is now managed for forestry. In the open spaces, which were formerly heathland, a wide variety of ponds and pools of various sizes provide a clean water habitat for several endangered water plants, particularly the aquatic fern Pillwort. This plant requires very clean, slightly acid, shallow water – protected from industrial agriculture and in Bramshill one of the largest remaining populations in the south of England occurs, outside of the New Forest. The ponds and pools are, because of their high quality, rich in a wide range of commoner plants and animals.

7. Rainham Marshes

Managed by the RSPB the ditches of Rainham Marshes give the lie to the old saying ‘as dull as ditch water’. Ditches in coastal grazing marsh may be straight and managed but they are far from dull. Simulating the networks of river channels that once wandered across the flatlands beside the estuary, ditches, so long as they are filled by clean water, have some of the most diverse freshwater plant and animal communities. Amongst the plants you may see Frogbit – with its miniature lily-pad like leaves and the yellow flowers of the carnivorous Common Bladderwort, the traps on its underwater leaves capturing passing water fleas.

8. The ponds and bogs of Chobham Common

The heaths west of London in Surrey and Hamsphire are a surprising and important part of the freshwater environment of the Thames catchment. Managed at low intensity with only the light grazing typical of old-fashioned chemical fertiliser-era farming, the bogs, streams and ponds of the Thames basin heaths are some of the best protected of our freshwater habitats. They support many species long gone from the ‘ordinary’ countryside including a wide variety of dragonflies – whose larvae like the acid water – and a rich water beetle fauna, including many species which never live in rivers or streams

Southern Hawker

9. The River Lambourne

The River Lambourne is a small chalk stream that flows through the Oxfordshire and Berkshire countryside to the River Kennet. Because of its high biological quality it is specially protected. The river supports a near natural invertebrate community and, formerly in lower reaches, the declining River Water-dropwort. There are populations of wild brown trout, and Brook Lamprey also occur.

10. Ponds of the Surrey Heaths

Heaths were once an even commoner feature of the Thames landscape from Hounslow in the east to Newbury in the west, and fringing the northern suburbs too, from Hampstead north. Some of these heaths, like those of the National Trust managed Headley Heath near Dorking still have high quality ponds where protection from pollution, combined with gentle grazing, provides the conditions needed by plants which are now rare in the Thames Valley, such as the delicate white flowered Starfruit and the submerged water plant Floating Club-rush, a plant of mildly acid water which does not survive in modern farmland.


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