We assess the quality of rivers and canals by looking at nutrients, chemistry, and biology. We sample about 7000 river and canal sites 12 times a year to test their chemistry and nutrients so we can see whether there are any pollutants and whether we need to target areas for improvement.
We currently have a three year rolling sampling programme to test the biology of rivers. We sample about 6000 sites twice during survey years to see what species are living in the rivers.
For chemistry and biology we classify A as being very good down to F for bad. Nutrients are analysed for nitrate and orthophosphate. We don't classify these as "good" or "bad" but just apply grades 1 (very low presence of nutrients) to 6 (very high presence of nutrients) We do this because rivers across the country naturally have different levels of nutrients and is not necessarily bad for the environment.
