Survey results from 2007 showing the health of phytobenthos (algae that grows on rocks on the river bed, also known as diatoms) expressed against the Water Framework Directive status classes. This is for a national selection of English rivers. The dataset also contains statistical information on the confidence that the results have been correctly assigned to each status class, taking into account normal and naturally occurring errors associated with measuring the environment. The assessment method has since been improved. Attribution statement: © Environment Agency copyright and/or database right 2019. All rights reserved.