Inverleith Park Pond
In 2006 Edinburgh City Council asked Nick Benge to come up with a solution to the problems being caused at Inverleith Park Pond by algae. The pond was getting blue green algal blooms that were a health hazard. These were principally caused by high nutrient levels in the pond. The solution we came up with was to desilt the pond and use the silt to create planting beds for masses of aquatic plants. In addition a curving boardwalk provided access over the water and through the plants. The idea was presented to a Friends of Inverleith Park meeting and accepted.
Solutions to the problem
Initially we drained the pond and allowed the silt to dry. The old tarmac causeway was ripped up and retaining timber walls built for the planting beds. The silt was then removed from the base of the pond and put into the beds and the boardwalk built. A gravel filter bed was also put in to help improve water quality. The incoming water was rerouted so that all the water coming into the pond had to pass through the wetland. The beds were planted up with big blocks of flag iris, Glyceria, greater and lesser pond sedge, Galingale and purple loosestrife. Bog myrtle and marsh marigold were planted round the edges. We had lots of fun to begin with trying to dissuade the 80 or so swans from eating the plants but this was solved when a dominant pair emerged, nested in the wetland and drove all the other swans away.
Since the wetland was constructed there have not been any blue green algal blooms. The plants absorb lots of the dissolved nutrients and the wetland traps sediment coming in with the incoming water. The biodiversity gains have been huge – heron and kingfisher are regular visitors; frogs spawn, and coot, moorhen and mallard regularly nest. Dragonflies and damselflies bask on the handrail of the boardwalk and sticklebacks swim through the starwort in the water. People love walking on the boardwalk and more generally the project has been a great success. It is wonderful to see that Inverleith Park Pond is now a popular visitor attraction. Water Gems were back recently to clean up the pond and ensure the water quality remains good.