OPAL Illuminate The Silt Problem At The Pond

Each year Fleet Pond Society (FPS) organises a very popular evening social event (that includes a dinner) that is open to members and their guests.

As part of this there is a presentation on a topic of interest. This year, Jim Storey, who is a Committee Member of FPS, gave a talk on how University College London, as part of the Open Air Laboratories (OPAL) network, is helping illuminate the condition and health of Fleet Pond.

Jim is very excited that Fleet Pond plays a part in the nationwide OPAL initiative and he was the driving force in organising the very successful event held at the Pond in May this year to celebrate International Biodiversity Day (see here and here).

Extracted from his talk, Jim highlights some interesting and important snippets:

“All the nine lakes that University College London (UCL) are studying have enhanced levels of brominated flame retardants. It’s not good for them and it is probably washed into the lakes from the air.

Simon Turner of UCL notes : “for all the lakes we have been able to quickly filter a litre of water. At Fleet Pond today we are only able to filter 300 ml before the filter clogs and stops working. Measuring depth and collecting samples never takes long here as the Pond is less than a metre deep. The trickiest part of sampling here is to avoid disturbing the sediment at the bottom.”

None of the lakes that UCL study are as silted up as Fleet Pond. They’ve measured the depth of silt around the Pond and found (see picture below):

That’s a lot of silt!

UCL have also taken a core through the silt in Fuglemere Bay and dated it back to 1870!

The table below shows how quickly the silt is deposited and how this has got so much worse in the last 10 years.

Period                  Silt Rate (cm / yr)

1973 – 1980        0.4

1980 – 1994        0.4

1994 – 2002        0.5

2002 – 2008        0.8

The core showed that more than TWO inches of silt were deposited between 2002 to 2008 – no wonder the Pond is in trouble!

Further details on the research results for OPAL Water can be found here (Fleet Pond is under the South East Region).

Leave a Reply