Home About the Stream The Partnership The Projects Research & Data News Archive Maps Links Contact Us

The Projects 2000-2007

 The Projects

 Bourne Valley Park

 The Greenway

 Coy Pond

 Valley Ponds

 Coy Pond Gardens

 Lagoons & Wetland

 Yellow Fish

 Use Water Wisely

 Op Streamclean

Click to view map showing locations of projects

 Bird's eye view of Coy Pond (click to enlarge)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.

Coy PondThe 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).

Coy Pond Project 2004-2006

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.


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.

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.

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.

22 February 2005

11 March 2005

Before the clearance

With the rhododendron cleared


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.

Coy Pond Water Quality

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. 

About the Stream • The Partnership • The Projects • Research & Data • News Archive • Maps • Links • Contact Us

Borough of Poole | Bournemouth Borough Council | Environment Agency | Sembcorp Bournemouth Water | Wessex Water Natural England | Bournemouth University | Greenlink | Bournemouth Oceanarium | Dorset Wildlife Trust | Dorset Coast Forum

Copyright © 2000-2012 Bourne Stream Partnership.  All rights reserved.


Disclaimer and copyright