Stations are listed from source to mouth as the water flows, traced on the river map (OS Open Rivers) and the Environment Agency’s own links between its gauges. A distance “by river” is along the river, and is shown only where the map traces the path.
Streams and rivers with a gauge whose water joins the Frays River above one of its gauges, from the source down. The river map knows where gauges are, not every stream, so a tributary without a gauge is not listed here.
None of the storm overflows FloodRadar holds is traced upstream of Yiewsley on the river map. That is not the same as none: the map leaves out many small streams and culverts, so an overflow it cannot place may still drain here, and not every company publishes every overflow.
1 other overflow within 3 km of these gauges is placed below the Frays River’s lowest gauge or on another river, so not listed.
Dated samples taken by the Environment Agency, not live readings. Results are published days to months after the sample is taken, and many points are sampled only a few times a year, or have not been sampled for years.
3 sampling points on the Frays River and the streams that join it above Yiewsley. 1 has a sample from the last 12 months; 1 has any sample banked. Listed from the source down, grouped by the next gauge each one's water reaches.
Distances are along the river to the gauge named. England's samples only.
FloodRadar does not grade these results: there is no overall score, and official river classifications are a separate dataset. A sample taken downstream of an overflow does not by itself show where anything in it came from. River connections and distances are traced on OS Open Rivers (edition 2026-04), which leaves out many small channels.
