|
Chew Valley Lake |
|
|
| Governing body |
Bristol Water |
| SSSI Ref |
1001346 |
| SPA Code |
UK9010041 |
Chew Valley Lake ( ) is a
large reservoir in the Chew Valley
, Somerset
, England,
and the fifth-largest artificial lake in the
United Kingdom (the largest in south-west England), with an area of
1,200 acres (4.9 km²).
The lake,
created in the early 1950s and opened by Queen Elizabeth II in
1956, provides much of the drinking
water for the city of Bristol
and
surrounding area, taking its supply from the Mendip Hills
. Some of the water from the lake is used to
maintain the flow in the
River
Chew.
Before the lake was created, archaeological investigations were
carried out that showed evidence of occupation since
Neolithic times and included
Roman artefacts. The lake is an important site
for wildlife and has been dedicated as a
Site of Special Scientific
Interest (SSSI) and a
Special Protection Area (SPA). It is
a national centre for
birdwatching,
with over 260 species recorded, including some unusual sightings.
The lake has indigenous and migrant water birds throughout the
year, and two nature trails have been created. The
flora and
fauna provide
habitats for some less common plants and
insects.
Some restricted use for recreational activities is permitted by the
owner,
Bristol Water, including
dinghy sailing and
fishing, primarily for
trout.
Location
Chew
Valley Lake in the Chew
Valley at the northern edge of the Mendip Hills, surrounded by meadows and woods and close to the
villages of Chew
Stoke
, Chew
Magna
and Bishop
Sutton
. When it was built in the 1950s, its
1,200 acres (4.9 km²) were flooded with
4,500 million imperial gallons (20,000,000 m³) of
water from the Mendip hills, with a catchment area of
14,000 acres (57 km²). It is relatively shallow, with an
average depth of only 14 ft (4 m) at top level and a
maximum depth of just 37 ft (11 m). It is fed by small
rivers, and it flows into the
River Chew
for 17 miles (27 km) before it joins the
Avon to head out to sea. The deepest
part is near the dam and the outlet tower, where the steeply
sloping shores of Walley Bank and the north shore result in depths
of up to 20 ft (6 m). "Denny Island", above the surface
throughout the year, is wooded and provides a habitat for
wildlife.
The lake
is owned and operated by Bristol Water, which created it in 1956
when the demand became too large for nearby Blagdon Lake
. Working with the
Avon Wildlife Trust,
Somerset Wildlife Trust and other
environmental groups, Bristol Water has encouraged various species
of birds and plants, and created a venue for visitors.
It has two large landscaped picnic areas. Facilities include a
tea shop, with indoor and outdoor seating
areas with a view of the lake, and information centre. There are
also a souvenir shop and small art gallery and two nature trails.
The Grebe Trail is a hard-surfaced, all-weather path suitable for
pedestrians, pushchairs and wheelchairs and covers a circuit
0.75 miles (1.2 km) long, starting and finishing at the
wooded picnic area. The Bittern Trail is reached from the Grebe
Trail by the footbridge over Hollow Brook. The grassy path is often
waterlogged in winter, but there is a boardwalk over a short
section. This trail runs along the east shore, visits an open bird
hide and returns to the footbridge, making a 1 mile
(1.5 km) circuit. Bristol Water impose conditions on visitors,
particularly related to the areas where dogs are allowed.
Access and transportation
Access to the waterside is restricted in places to reduce the
disruption to wildlife. Paths around the lake are generally flat
and, where paths are surfaced, wheelchair access is possible.
Visitors are officially invited to use public transport, but
overwhelmingly arrive by private car, encouraged by the provision
of parking spaces. The "Chew Valley Explorer" bus route 672/674
provides access.
In 2002 a 1.9 mile (3 km) safe cycle route, the Chew Lake
West Green Route, was opened along the B3114 along the western part
of the lake.
It forms part of the Padstow
to Bristol West Country
Way, National Cycle Network
Route 3. It has all-weather surfacing,
providing a smooth off-road facility for ramblers,
mobility-challenged visitors and cyclists of all abilities. It was
funded by
Bath and North
East Somerset Council with the support of
Sustrans and the Chew Valley Recreational Trail
Association. Minor roads around the lake are also frequently used
by cyclists.
Bristol
International Airport
is approximately 10 miles (15 km) away,
and the nearest major road is the A368,
which runs along the southern edge of the lake and provides access
from Bath and Weston super Mare. The A37 and A38 are slightly
further away, providing access from Bristol. Car
parking is available at the visitor centre and Woodford Lodge, for
which a charge is made, and a small amount of parking is available
at various points around the lake; some of these are restricted to
those with fishing permits.
History
Plaque unveiled by Queen Elizabeth II
in 1956
area the lake covers was once rich farmland. Farms and houses had
to be removed before the land was flooded, and old roads, hedgerows
and tree stumps can reappear when dry summers cause the level of
the lake to drop. Prior to the flooding of the
reservoir,
archaeological excavations were carried out by
Philip Rahtz and
Ernest Greenfield employed by the
Ministry of Works, from
1953 to 1955. The excavations found evidence of people belonging to
the consecutive periods known as
Upper Palaeolithic,
Mesolithic and
Neolithic
(Old, Middle and New
Stone Age),
Bronze Age and
Iron Age,
including implements such as stone knives,
flint blades and the head of a
mace, along with buildings and graves.
The
artefacts from this period
are held at Bristol City Museum and Art
Gallery
. Further evidence of Neolithic and Bronze Age
occupation is provided by the archaeological survey of the Mendip Hills Area of Outstanding Natural
Beauty.Excavations have also uncovered Roman remains,
indicating agricultural and industrial activity from the second
half of the first century to third century AD. These finds included
a moderately large
villa, at Chew Park
where wooden writing tablets (the first in the UK) with
ink writing were found.
The tablets were sent to the British
Museum
, but other Roman material is on display at the
Bristol City Museum and Art Gallery with the lake's other
historical artefacts.
Further excavations around the village of Moreton, which has now
been totally submerged, found evidence of a thriving community in
medieval times and possibly the remains of
the
Nunnery of Santa Cruz. During the
Middle Ages farming was the most
important activity supported in the area covered by the lake,
supported by four
flour mills powered by
the River Chew.
Stratford Mill was demolished and re-erected
in the grounds of Blaise
Castle
Museum, in north-west Bristol. The largest
settlement was Moreton, which is listed in the Domesday Book and survived until the flooding
of the lake, when the remains of the Moreton Cross were moved to
Chew
Stoke Parish Church. There is also evidence of
lime kilns, which were used in the
production of mortar for the construction of local churches.
Farming, both
arable and
dairy, continued until the flooding of the
lake, with most households also keeping
pigs.
There were
orchards for fruit production,
including
apples,
pears
and
plums. In recent years there have been
sightings of a ghostly young girl who has been seen by local people
crossing the B3114 walking towards the lake.
Reservoir
Pumping Station
Plans for the building of the reservoir were under discussion
before the
Second World War, and an
Act of Parliament submitted by the
Bristol Waterworks Company was passed in 1939. Following this,
farms were bought by the company and farmed by the previous owners
as tenancies. Farms and buildings still remaining in private hands
were acquired by
compulsory
purchase. The sanction for construction was given in 1949 and
the contract awarded to A.E. Farr & Co., who employed
approximately 300 people on the site. The main
dam was initially stabilised by injecting
concrete into the cracks in the
bedrock. The core of the dam was made of
puddled clay
mixed with
sand. This was the first time the
gain in strength brought about by the use of sand drains had been
quantified. The lake was inaugurated by
Queen Elizabeth II,
accompanied by
Prince
Philip, with the unveiling of a commemorative stone and plaque,
which can be seen from the dam, on 17 April 1956, although it was
not full until 25 February 1958. Flowers were presented to the
Queen at the opening of Chew Vally Lake by Judith Blair Brown,
daughter of Kennedy Brown, who worked at Bristol Water Works at the
time of construction of the lake.
During the storm of 10 July 1968, the lake gained an extra
471 million imperial gallons (2,140,000 m³) and rose
19 inches (480 mm) in under 12 hours.
At one point worried
Bristol police issued a warning
that the dam might not hold, prompting localised evacuation of
populated valley areas downstream including Pensford
and Keynsham
.
Ecology
View of Chew Valley Lake showing
Herriot's Bridge
The lake is designated a
Site of Special Scientific
Interest (SSSI) (Site Ref: 1001346) and a
Special Protection Area (SPA) (Site
Code: UK9010041) largely because of the diversity of species and
habitats.
Providing further protection, much of the
area around the lake also falls within the Mendip Hills Area
of Outstanding Natural Beauty (AONB).
The lake appears to have a higher sedimentation rate than would be
expected in other similar reservoirs, being in the region of
100–150 t.km
-2.yr
-1.
Geology
The main geological outcrops around the lake are
mudstone, largely consisting of red
siltstone resulting in the underlying
characteristic of the gently rolling valley landscape. There are
also bands of
sandstone of the
Triassic period that contribute to the undulating
character of the area. There are also more recent
alluvial deposits beside the course of the River
Chew.
Birds
Drake in flight on Chew Valley
Lake
Over 280 species of birds have been recorded at Chew, an
internationally important site for wintering and migrating
wildfowl. From late July to February, up to 4000
ducks (Anatidae) of twelve different species may be
present, including internationally important numbers of
Northern Shoveler (
Anas clypeata)
and
Gadwall (
Anas strepera). Up to
600
Great Crested Grebes
(
Podiceps cristatus) gather to moult on the lake in
autumn. A wide range of data on bird species and their numbers on
the lake, dating back to the first "
ringing" in 1964, is available from the Chew
Valley Ringing Station.
Numerous other birds can be seen, especially during the spring and
autumn
migration.
Sand Martins (
Riparia riparia) arrive
early and can usually be seen hawking over the water for insects in
the second or third week of March. Flocks of
tits (Paridae),
swallows (Hirundinidae) and
terns (Sternidae) can regularly be seen. Waders, such
as
Lapwings (
Vanellus
vanellus),
Dunlin (
Calidris
alpina) and
Common Snipe
(
Gallinago gallinago), are attracted to the muddy shores
if the water level drops in autumn. By midwinter up to 55,000
gulls, mostly
Black-headed Gull (
Chroicocephalus
ridibundus) and
Common Gull
(
Larus canus), may be roosting. Good numbers of
Reed Warbler (
Acrocephalus scirpaceus)
and
Sedge Warblers (
A.
schoenobaenus) nest in the fringing reeds, along with
grebes (Podicipedidae) and
Eurasian Coot (
Fulica atra).
Much of the management work carried out in the nature reserve is
aimed at encouraging ducks to breed, and small numbers of
Tufted Duck (
Aythya fuligula),
Common Pochard (
Aythya ferina),
Common Shelduck (
Tadorna
tadorna) and
Gadwall raise broods most
years. Recent breeding successes also include
Water Rail (
Rallus aquaticus) and
Cetti's Warbler (
Cettia
cetti).
A new wetland reserve has been created at Heron's Green Pool on the
opposite side of the causeway to the lake. A large shallow pool
fringed with
sedges (Cyperaceae),
rushes (Juncaceae) and
reedgrasses (
Calamagrostis) and
surrounded by lightly grazed, rough
grassland may also prove attractive to Snipe and
Lapwings.
Fish
In late summer large shoals of
Common
Roach (
Rutilus rutilus) and
perch
(
Osteichthyes) fry can congregate around the margins and
weed beds, which are predated by the
brown
trout (
Salmo trutta morpha
fario) and
rainbow trout (
Oncorhynchus
mykiss).
Insects
Aquatic midges (
Chironomidae)
provide the highest proportion of the fly life of the Lake. The
trout (
Salmonidae) will feed at the
surface on these and
water boatmen
(
Corixidae), and below the surface on the
caddisfly (
Trichoptera)
larvae and
pupae; they will also
take the adult Caddisflies when they emerge. Other aquatic fauna
including
daphnia and
snails are also found in the lake. Large populations
of
dragonflies, including
Migrant Hawker (
Aeshna mixta) and
significant numbers of
Ruddy Darter
(
Sympetrum sanguineum) occur. Eleven species of
wainscot moth make their home in the reed beds,
including the nationally local Brown-veined Wainscot (
Archanara
dissoluta) Twin-spotted Wainscot (
Archanara
geminipuncta) and Silky Wainscot (
Chilodes
maritimus).
Vegetation
The lake is surrounded with fringing
reedbeds,
carr woodland
and
grassland, which are managed by
Bristol Water. The water conditions
are
eutrophic with run off from local
fields and streams. Open-water plant communities are rather sparse,
largely comprising
fennel pondweed
(
Potamogeton pectinatus),
lesser
pondweed (
Potamogeton pusillus),
opposite-leaved pondweed (
Groenlandia
densa) and
water-crowfoot
(
Ranunculus spp.). On neutral soils around the reservoir,
pepper-saxifrage (
Silaum silaus),
burnet-saxifrage (
Pimpinella
saxifraga) and
devil's-bit scabious
(
Succisa pratensis) occur, and on calcareous soils
fairy flax (
Linum catharticum),
dwarf thistle (
Cirsium acaule) and
salad burnet (
Sanguisorba
minor subspecies
minor) are found.
The small and medium-sized fields around the lake are generally
bounded by hedges and occasionally by tree belts and woodland, some
of which date back to the most evident period of enclosure of
earlier open fields which took place in the late medieval period.
Mature
oak (
Quercus) and
ash (
Fraxinus excelsior) trees are
characteristic of the area with occasional groups of
scots pine (
Pinus sylvestris) and
Chestnuts (
Castanea sativa). Many
elm (
Ulmus) trees have been lost in
this area, and dead/dying elms are also evident in the surrounding
landscape.
Four areas of woodland containing 157 trees has been planted by The
Life for a Life Charity around the lake on the Restaurant side, for
the cremated remains of loved ones to be placed beneath them. These
forests contain
Scots Pine (
Pinus
sylvestris),
English Oak
(
Quercus robur),
Rowan (
Sorbus
aucuparia) and the
Silver Birch
(
Betula pendula).
Leisure use
The lake is used for a wide variety of leisure pursuits.
Birdwatching
Birds on Chew Valley Lake taken from Herriott's Bridge
During 2005–2006 Bristol Water started restoring two artificial
islands. These are intended to provide safe nesting and roosting
sites for a range of wildfowl. Permits to enter the reservoir
enclosure and to use the access roads, paths and bird hides are
available (for a fee) only to members of ornithological and
naturalist societies recognised by Bristol Water. They can be
obtained from Woodford Lodge and include conditions of use imposed
by the owners.
Sailing
Chew Valley Lake Sailing Club
Chew Valley Lake Sailing Club has a large sailing area,
approximately 1.9 miles (3 km) long, for
dinghy sailing. The lake is divided into two
areas: a restricted summer area which is available during the
fishing season (mid-March to mid-October), and the full area which
can be used throughout the winter and on Sunday afternoons. The
sailing area is marked out by lines of small white buoys. Racing
marks are red buoys with flags, although large inflatable marks are
used of open events.
The club can cater for fleets of over one hundred boats and it
hosts large national events. Normal club racing has fleet starts
for the following dinghy classes:
Flying Fifteen ,
Laser ,
Solo and
Topper as well as a handicap fleet
run under the
Portsmouth
yardstick scheme. Five separate slipways enable easy launching.
Off the water, the clubhouse facilities include large changing
rooms, hot showers, hot food at the weekends, a bar and terrace
overlooking the lake. The club also caters for disabled people with
facilities on both floors and a lift. Various
Royal Yachting Association
sailing courses are held at the club for members including race
training, youth training, powerboat training, race officer training
as well as more informal training run within each fleet.
Fishing
Seasonal day and afternoon bank fishing permits are available at
Woodford Lodge. The restrictions imposed by Bristol Water mean that
no fishing is allowed from the
dams or stone
embankments, the sailing club,
in front of Stratford bird hide, in front of the
picnic areas and in the
nature reserve, and various other regulations
are in force. There is a fleet of 32 motor boats for hire to
fish.
References
Bibliography
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