For those of you interested in Dart water quality measurements in detail, the following link will take you to a list of the twenty most recent sampling results at Totnes weir, from Nov 2019 to May 2022.
https://environment.data.gov.uk/water-quality/view/sampling-point/SW-70720104
(Opens in new tab)
There are also some classification data here:
Dart | Catchment Data Explorer | Catchment Data Explorer
The latter appear to be the latest data available, from 2019 (opens in new tab)