Water Quality

In addition to chemical checks, the presence/absence and abundance of certain freshwater invertebrates (often called macroinvertebrates) – the aquatic larval stage of various insects - can tell a story of a water body’s health. Because some invertebrates are more sensitive to pollutants than others, we can use them as “indicator species”.
Assessing the types of invertebrates found indicates something about the health of the water body they have been found in. For example worms can tolerate high levels of pollutants but some mayflies don’t tolerate even low levels of pollution. They also help describe when pollution events occur because some populations take a while to recover if they have been harmed by pollution.
The Trust is working with Frensham Fly Fishers who have a long-established routine of regular sampling, and we will be working with them to extend the scope of sampling in our branch of the river, combining findings and understanding how and where the river environment and water quality is being impacted. This supports the Riversearch Wardening scheme run by the Surrey Wildlife Trust.
The Trust monitors water quality using chemical testing and ecology sampling - the current reports for the Trust's own site at Allee's Meadow are shown below.

The Trust works with other groups and organisations such as Water Rangers along the river to monitor quality; to see the full set of monitoring points on the river - open the River Wey group page:


Invertebrate Sampling

Test Date04 Dec 2021 15 Jan 2022 12 Feb 2022 19 Mar 2022 16 Apr 2022
Location Allees Meadow Allees Meadow Allee's Meadow Allee's Meadow Allee' Meadow
Reporter5 RWT Volunteers4 RWT Volunteers 6 RWT Volunteers7 VolunteersRWT Volunteers
Indicator InvertebratesScoreEstScoreEstScoreEstScoreEstScoreEst
Flat Bodied HeptagenidB15B15B13B31C101
Mayfly A2A1
BWO B15
OlivesA1A2A1B10B34
Stoneflies A3A2
Caseless CaddisB30B10B25B12C101
Cased CaddisB20B12B12B13C101
GammarusD1001D1001D1001D1001D1001
Quality Score1111111419
Other  Est Est Est Est Est
Bullhead 3 1  1 1
Riverine Woodlouse  1   1

Water Quality Results

The River Wey Trust: F