Welwyn Natural History Society has organised a talk by Thames Water's Sustainability Director, Richard Aylard. on the topical issue of river pollution from storm overflow water containing raw sewage (8pm, Wednesday 26 April, Welwyn Civic Centre, AL6 9ER)

He will describe a new operational system for monitoring storm overflows and discuss how discharges can be reduced.

WNHS has also provided the link to an online map published by Thames Water that shows the status of several hundred monitors including those in Hertfordshire.

An Environment Agency video and a description of how the Thames Water monitoring system works is also available online.

Photo: © Rivers Trust