Hogsmill - an update
The Hogsmill is one of only 200 chalk streams on the planet!
In the January issue of E-Borough Insight, we highlighted concerns about the low levels of the Hogsmill, which poses a threat to the ecology of the river. We have been working with the various partners in the Hogsmill Catchment Partnership to try and understand the problem and work out a solution.
Bourne Hall Pond is fed by a natural springs and the pond's fountain is used to top up the water level and increase the flow to the Hogsmill for the benefit of the river and its wildlife. Last month, following advice from the Environment Agency, SES Water temporarily turned off the fountain in Bourne Hall Park Pond.
Almost immediately the level of the neighbouring Horse Pond began to drop and continued to do so until the level stabilised at the level of water in the sump to the weir, curtailing the flow to the Hogsmill River. This result indicates a possible problem with the weir or a leak in the Horse Pond, with water retuning to the water table aquifer rather than flowing into the Hogsmill. The latest view is that some further experimentation is required to ensure there is no back flow from the Upper Mill Pond that could be masking a leak in the bed of the Horse Pond.
The fountain was turned back on at the start of March and it is hoped that Environment Agency will renew the temporary licence issued to SES Water in forthcoming weeks to allow the investigation to continue.