Saturday, October 19, interested parties, including members of the Bovenkerk sustainability committee, had the opportunity to learn more about the ecology and water management of the Amstelveen Poel. During a boat tour, organized by the Rijnland Water Board in cooperation with the Amsterdam Forest, the recently launched pilot project to improve water quality was explained. This project focuses on the so-called Modderpoel, the extension of the small Poel at Bovenkerk , and represents an important step in addressing water pollution in this unique nature and recreation area.
Poor water quality
The Amstelveen Poel, created by peat extraction in the 18th century, has been struggling with poor water quality for some time. Blue-green algae, caused by high phosphate and nitrogen levels, is a recurring problem. This makes the water unsuitable for swimming and poses a risk to both humans and animals. Contamination by toxic substances, such as PFAS that comes from anti-ice pesticides from airplanes at Schiphol Airport, among others, also plays a role. On the Kleine Poel, incidentally, the water quality is worse than on the Grote Poel.
Paul Hollander, project manager of the Water Board, explained that a lot has been accomplished since the 1980s by disconnecting the sewers from the stormwater runoff and treating the water better. The dog policy, where poop is cleaned up in special bins, also helps keep the water cleaner (dog poop is a major source of e-coli bacteria in the water).
The pilot project
In this pilot they are removing dredge, which includes heavy metals and toxic substances, from the bottom. After dredging, a one-and-a-half-meter layer of sand is applied to the bottom so that phosphate and PFAS from underlying layers no longer enter the water. This should help reduce algae growth, which harms water quality. Work is underway and is expected to last until early 2025.
For the duration of the project, the passage between the Amstelveen and Kleine Poel will be closed with a sheet pile wall. This will ensure that the water of the Mud Poel remains isolated so that the effects of the dredging can be closely monitored. After completion, the water quality will be monitored for five years to determine whether the measures are actually having an effect.
Ecological value
During the tour, forester Pieter Rust explained the special ecology of the reeds and peatlands of the Poeloevers. The banks, which are older than the Amsterdamse Bos itself, form a nature reserve of great ecological value. Rare plants, including carnivorous species, grow here, and the natural dynamics of the floating peat ensure that the vegetation constantly adapts. The preservation of this valuable nature is essential and requires ongoing efforts, such as annual mowing of reeds to prevent desiccation and land degradation.
Outlook
There is still a long way to go. The current pilot project is an important step in reducing pollution and restoring the natural balance in the Kleine Poel. Should the pilot prove successful, this project could provide a blueprint for further improvements throughout the Amstelveen Poel. The Water Board remains committed to cleaner water, not only to increase the recreational value of the Poel, but also to protect the area's rich wildlife for future generations.