Beck-blitz

On Saturday 13th and Sunday, 14th June we had a new event at our sites which we have nicknamed a beck-blitz. Our resident water expert – David Harper – designed this event to train citizen scientists to be able to identify the health of water courses from both their physical attributes and the life within them.

I joined a dozen people on the chilly Saturday morning to learn about the physical properties of watercourses. These features can be indicators of the naturalness of a stream or river. After a brief introduction we were sent off to look at the Gur Beck, the chalk stream that runs through Spurrell’s Wood and into Sustead Common and the Surveyor’s Allotment. Using our observations and guidance from David, we identified the main properties of a watercourse. David then explained a system he has created to assign a score to these features, using a simple multiple-choice form, to produce an overall evaluation of the health of the watercourse. Then off we went in groups as guinea pigs of this new scheme to assess the Gur Beck. We gathered for a final session, which raised a range of questions which will help David to refine the questionnaire.

Identifying Water Creatures

Sunday was warmer, and was devoted to biological monitoring. When we arrived, David had already taken a three-minute kick sample from the stream, and we found trays of water with gravel and a myriad of small creatures in them waiting to be identified. David explained that we would be learning the Extended Riverfly system, which uses the presence (or absence) of 33 groups of invertebrates to measure levels of pollution and degradation of watercourses. We were given the Extended Riverfly identification sheet and a few clues as to which features to look for (including “how many tails does it have?”), and then left to get on with it. It seemed baffling at first, but with added hints from David when we were struggling to work out what we were looking at, we began to identify the different groups – Olive and Green Drake Mayflies, various cased and caseless caddis flies, worms and beetle larvae, leeches and flatworms… By the end of the session, we had really begun to get our eye in and had identified that we had 20 of the 33 groups in our sample, which seemed a pretty good selection, and few of the indicators of poor habitat were found, suggesting a pretty healthy stream. Along with an assessment of the abundance of the various groups, this information can be used to create an overall score for the watercourse.

Green Drake Mayfly

I enjoyed the training tremendously, and it was great to be working with a group of like-minded enthusiastic people under the expert tutelage of David. The highlight for me was the emergence of an adult Olive Mayfly and a Green Drake Mayfly from our sample – beautiful and magical.

Green Drake Larva

David is planning to repeat the training session several times over the next few months, so if you missed it this time, there will be plenty of other opportunities to participate in this fascinating workshop.

Val Stubbs

14th June 2026