Wimbledon Park Lake is really the jewel within the landscape created by Capability Brown. Although much of the surrounding area has changed since Brown's day, the lake and its configuration have remained essentially unchanged.
So, for over two hundred years now this body of water, which is officially designated a reservoir, has accumulated dirt and grim which when mixed with water has created a prodigious level of silt. In addition we have a considerable population of waterfowl who are well supported by the many park visitors who take such delight in feeding the ducks, geese and swans. However, this large waterfowl population has increased the PH levels found in the lake which effects water quality.
Because of the state of the water quality, the only fish who can survive in the lake are now large carp, which the Angling Club regularly fish.
The lake does benefit from underground aquifers and streams which gain fresh water from the gravel beds found on Wimbledon Common, but at times this isn't sufficient to maintain a standard of healthy water quality.
Further, during the summer the lake is subject to extensive blooms of green algae which can really be most difficult to control. Barley straw has been used in the past but more recently its application has actually made the situation worse due to the bales of straw breaking up and creating flotsam around the lake, which eventually sinks to the bottom and rots thus throwing off CO2 and generally not being helpful at all.
Recently a product has been found that may have a solution for the lake's water quality problems. The composition of silt is basically 80% water and 20% substrate. A product developed in France and called Aquaplancton separates the water from the substrate with the projected result of achieving a 70% to 80% reduction in the silt base found in a lake with the released water being clean and clear. The remaining substrate is mineralized and falls to the bottom of the lake. As green algae and blanketweed feed on silt, the reduction of the silt has an equal effect on both of these problem microbes.
The Max-Planck-Institute of Ornithology maintain a 19 acre lake called Goose Lake near Munich, Germany. Goose Lake's profile of problems were a very close fit to those found in Wimbledon Park Lake. Twenty years ago, Aquaplancton was used to reduce silt, halt algae bloom and improve water quality. All of these goals appear to have been achieved, but that was twenty years ago and although the product is certainly of interest, it is necessary to validate more recent results gained by current UK users. The Heritage Group will be visiting UK sites that use the product.
For some years now, there has been a discussion regarding the reduction of silt by dredging the lake. The reason this approach hasn't gained support is the cost which is estimated to exceed one million pounds. Add to that the disruption caused by traditional dredging methods to everything involved in the lake from the wildlife to the general use of the lake by both the Watersports Centre and the Angling Club which resulted in traditional dredging methods being deemed not realistic. However, new technology may well mean that dredging is the way to go. For a short video showing how Goose Lake was dredged in 2010 at a cost of 1,200,000 Euros by the German company Wurzer, go to this site: