Site Registration Form — Notes and Guidance

We are working on a project that we are calling ‘Targets and Triggers’, and we need monitors to collect some extra data over the next few months.

We have a new Site Registration Form here that includes further details on the width, depth and substrate at your sites — please could you collect this information, fill in parts 2 and 3 of the form, and send it directly to us (info@riverflies.org). We need these details for your sites collected during summer (June/July/August), autumn (September/October/November) and next spring (March/April/May). With this data we hope to be able to help our statutory bodies set appropriate trigger levels and potentially some target levels for your sites.

Below is some guidance on how to collect these pieces of data, taken from this macroinvertebrate sampling manual (available on the FBA website).

Width Measurement

  1. Choose a point that reflects the predominant conditions in the sampling area. Measure the width of the water surface (not the stream channel) at right angles to the channel. Include water under overhanging banks and any temporary islands that have formed in the channel because of low flow. Use a metre rule, marked pond net handle, river-crossing pole or tape measure.

  2. For wide or deep rivers that cannot be waded, use a calibrated rangefinder or estimate the stream width making use of nearby bridges.

  3. Try not to estimate. However, if you have to, estimate widths as follows:

    • <1 metre to the nearest 10 cm;
    • 1 - 2 metres to the nearest 20 cm;
    • 2 - 10 metres to the nearest 50 cm;
    • >10 metres to the nearest metre.

  4. Use the definition of widths below.

Depth Measurement

  1. Reflect the predominant conditions in the sampling area. Average measurements from a quarter, half and three-quarter distances, across the stream transect, within the sampling area (where the width is the water surface).

  2. In periods of low flow, the depth at a quarter and three quarters channel width will be measured closer to mid-channel than at other times. If there is a temporary island at a measuring point, the depth there will be zero. Record it as this.

  3. Use a marked pond net handle or a metre rule. When using a rule, ensure that the narrow edge is facing the current to avoid distortion. In deep rivers when airlifting a sample, mark the anchor rope and airlift rope with 10cm intervals to aid depth measurements.

  4. If the stream is wadeable, record the depth to the nearest centimetre. If the depth cannot be directly measured, estimate it as follows:
    • <1 metre to the nearest 10 cm;
    • >1 metre to the nearest 50 cm.

  5. It is difficult to estimate depth in deep rivers. However, the predictive equations that will be used to set target and trigger levels are robust enough to withstand a reasonably wide range of error in the greater depth range.

Substrate Composition

  1. Assess the composition of the stream bed over the whole sampling area. That is, the full width of the river along the whole length sampled, even if parts are inaccessible. Your estimates should represent a bird's eye view. Only include particles on the surface of the stream bed, including the equivalent superficial layers under plants.

  2. If you can see the shape of underlying stones through a fine layer of silt or clay, record the underlying substrate. If the shapes of the underlying stones are not distinct, record the silt or clay.

  3. Record compacted clay as clay, even when broken up into gravel-sized fragments.

The table below lists the substratum particle size categories:

How to record the percentage cover:

  1. Walk along the river bank and make a preliminary note of the substratum. Initial evaluations are very useful at silty sites and help decide the appropriate level of sampling effort in different habitats

  2. After your kick sample, walk over the whole sampling area to make final estimates.

  3. It is difficult to judge the composition of the river bed in deep or turbid water. Use the substratum visible at the water's edge, the feel of the stream bed under foot, the contents of the sampling net, previously recorded data and local knowledge to help.

  4. Percentage cover estimates are subjective but can be improved by experience and by comparison with a someone else’s estimates.