34. Grovelands Park Reedbed
Theme: Water quality
Objective:
- Reduce the frequency and severity of pollution
Project description
Part of the Salmons Brook Healthy River Challenge
The lake in Grovelands Park, Enfield is the centrepiece of a beautiful and grand garden for the 'Southgate Grove' mansion, sesigned in the 18th century and now a well loved popular public park. Sadly the lake is afflicted with pollution from a number off surface water drains, and toxic algal blooms are common in summer. Rainwater running off local streets brings with it oils and heavy metals from the road, as well as detergents and other chemicals such as phosphates and nitrates from misconnected plumbing. This pollution load limits the lake's potential as a wildlife habitat and its appeal for park visitors.
In June 2015 we created a reedbed in the south western end of the lake to naturally break down these pollutants and increase oxygen levels in the water, as well as providing new habitat for birds and insects. Coir rolls and hazel faggots were used to create an area of suitable depth to establish the reedbed. Coir mats pre-planted with reeds, rushes, sedges and colourful purple loosestrife and yellow flag iris were installed across the reedbed area, protected from wildfowl grazing by netting.
The plants use excess nutrients such as phosphates nad nitrates to grow, preventing them building up in the water which causes the toxic algal blooms. The plants also oxygenate the water. Bacteria growing in the sediment and root systems break down oils and some bacteria can even reduce levels of heavy metals in the water.