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 Coy Pond
Coy
Pond, Poole was created in 1888 at the time the railway
embankment was constructed behind it; its name is a reminder of a
previous life as a decoy pond.
 The
pond is now fronted on three sides by residential property and by
Coy Pond Gardens
to the south. It features a wooded island, and supports a number of
waterfowl species including Coots, Moorhens, Mallards and Canada Geese.
Water enters the pond
via a brickwork inlet structure which creates a turbulent flow, and
exits through a grilled piped outfall system which takes flow below Coy
Pond Gardens where it converges with the second tributary of the Bourne
Stream about 50m away. The combined flow then continues downstream to
Bournemouth and the Pier.
The
pond and gardens cover 9 acres (3.65 hectares), of which the pond covers
an area of 0.84 acres (0.34 hectares). Unlike other ponds along the course of the Bourne
Stream it does not
lie within a SSSI designation area. The gardens associated with
Coy Pond are Grade
II* listed by English Heritage (as are Bournemouth's Upper, Middle and Lower
Gardens).
Following
public consultation in August 2000, Borough of Poole's Leisure Services
produced the Coy Pond & Gardens Management Plan (2001-2006). |
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Clearing
the island & dredging the pond
The
number of trees and shrubs surrounding the pond contribute a huge amount
of organic material (twigs and leaves) to the pond, and the stream
brings quite large amounts of sandy soil from Talbot Heath. Over
time the pond becomes silted up.
Responses
from the public consultation in 2000
revealed that respondents felt the dredging of Coy Pond was of the
highest priority.
The build up of
rotting vegetation and other organic matter reduces oxygen levels in
water that can make it unsafe for fish and other aquatic creatures, and
unattractive for visitors, so it's important the the pond is dredged on
occasion. It
would appear that the pond was last dredged (or actually drained) more
than ten years ago ...
"The
Coy pond was drained in April 1994 during our visit to the sample site.
Sediment from the bottom of the pond was entrained and flowed
downstream." (Armitage et al, 1994).
Nowadays
environmental considerations would not allow us to release sediment
downstream. Apart from the fact that it's likely to be
contaminated with
years of waste from the large number of fish and wildfowl in and on the
pond, the release of any sort of sediment into the stream is
unsustainable (and illegal). Particles will
settle downstream wherever the velocity of water flow is reduced, with
the potential of smothering any organism living on the stream bed; the
turbid conditions produced will also affect photosynthesis, respiration,
and reproduction of aquatic life.
Due
in part to these environmental considerations, it
is not nowadays economically viable to dredge the entire pond. It's likely that the pond would need to be
drained which is costly, and disposing of the
huge amount of material removed from site is an
extremely expensive operation.
Borough
of Poole Leisure Services worked out (and agreed with the
Environment Agency) a comparatively inexpensive method of carrying out
some much-needed maintenance dredging which will focus on
areas of particular concern, and use sediment on site, to rebuild the
eroding island.
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 A
partial dredging of the pond in December 2004 was such a success that Poole's Leisure Services
Unit agreed to tackle a larger area of settled sediment in 2005.
 Before
we could do that
we had to clear the island of dense rhododendron cover (photo left,
more below), brambles and other undergrowth to allow access to
excavators. Unfortunately that happened later than we'd
hoped and by the time we were ready to dredge we had at least two
moorhens nesting at the northern tip of the island that we couldn't disturb.
In
February 2006 we returned to finish the job by laying timber supports around much of the island, using the
trunks of trees recently felled in the Borough. We then excavated sediment
from around the island and used that material (mainly sand and organic matter)
to infill between the island and timber supports, increasing its
size, improving the soil condition and preventing further erosion of it.
Further
Dredging
Poole's Leisure Services will be working on a plan to
economically clear the section of sediment closer to the pond
outlet, and find the funding for it.
This may or may not be achievable. Other measures are
being investigated to reduce the sediment load to the pond that is
washed downstream from Talbot Woods.
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Planting
the Island
By April the island had dried out sufficiently to undertake some
planting. With the help of £300 very generously donated
by the Friends of Coy Pond,
we purchased a range of species from Stewarts Nurseries.
Angela Mann Garden Design was commissioned to advise on the
selection and carry out the planting, assisted by her colleagues
Nick & Dave, and residents Ken Smithurst, Phil Jones &
Derek Jewel - 242 container shrubs & plants and 4 trees
planted in 7 hours.
One
of the trees - an Acer - has been dedicated to the lovely Dorothy, a very
good Friend of Coy Pond who walked the area daily, and who sadly
passed away shortly before the island works were completed.
A second round of planting took place in early December 2006,
when Angela & Nick returned to add 124 'whips' and small plants
to complete the full range of our target species - mainly native, non-invasive and
attractive to a wide range of birds, butterflies and insects.
We also took the opportunity to plant 500 native bluebell bulbs
to provide Spring colour beneath the pine trees. |
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Rhododendron
Clearance
We
cleared large sections of rhododendron to allow the excavators to access the island borders for dredging, but that's not altogether a bad
thing. Rhododendron can look
attractive in flower, but much of it at Coy Pond had become old, straggly and out
of control.
Rhododendron also does little to enhance its environment in terms of
wildlife benefit.
It supports very few species, shades out other plants and the
dense cover prevents the successful germination and establishment of
tree seedlings so there’s no natural replacement for canopy trees that
die.
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Before
the clearance |
With
the rhododendron cleared |
Reference:
Patrick
D. Armitage, John H. Blackburn & Kay L. Symes:
The environmental quality of a small urban water course, the Bourne
Stream (Dorset), assessed with macroinvertebrate data. 1994,
Institute of Freshwater Ecology. Full
text available here. |
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Coy Pond is an ornamental pond and home to a number of ducks and geese, all
of which are regularly fed large quantities of bread and other food scraps by residents and
visitors. It is widely recognised that the high level of organic
matter produced as a result of overfeeding waterfowl has a detrimental
effect on water quality (read Feeding
the ducks).
There is evidence of
this in results from the Environment Agency's analysis of water quality
sampling during 2003.
Water tested at the inlet and outlet of
the pond show significant increases in levels of both ammonium and
faecal coliform cells (charts below illustrate mean data, summer 2003)
and the
level of ammonia at the pond outlet is more than 3x average levels for
the rest of the stream.
If
the pond were not refreshed by a constant supply of stream water, this
pollution would eventually cause problems for all life in and on
it.
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