Natural obstacles to fish or flow

This parameter is part of the newly defined UK National Protocol as part of CaSTCo. This description is preliminary and will be updated shortly.

Interruptions to flow can sometimes be beneficial as they create sections of faster or slower flow, which can help to expose clean gravel sections; woody material in rivers is also generally beneficial as it provides habitat for invertebrates. In some locations obstructions can be problematic e.g. where they cause unwanted bank erosion or risk blocking a downstream culvert or bridge. It can be particularly useful to submit a photo of any temporary obstacles and to monitor whether they are growing over time.

Record temporary barriers to flow – permanent barriers such as weirs, steps or culverts can be recorded in the location desscription.