Exploring the viability of a simplified watercourse condition assessment for Biodiversity Net Gain

Background

In May 2025, the government launched an 8-week consultation on improving the implementation of biodiversity net gain for minor, medium and brownfield development. This consultation was supported by a detailed consultation document. As part of this consultation, the government sought views on the proportionality of using the River

Condition Assessment survey method in different scenarios, particularly for minor developments where part of the proposal falls within the riparian zone or where there are no anticipated or likely impacts.

Responses to the watercourse questions highlighted that river condition assessment survey effort should be proportionate to the level of 'impact' a development has on the watercourse feature, should be proportionate to the distinctiveness category of the watercourse, and be assessed by a competent ecologist. Further details can be found in section 4.4 of Government response and summary of responses - GOV.UK.

For the purposes of Biodiversity Net Gain (BNG), the River Condition Assessment methodology is currently used to assess the condition of Priority River Habitat, 'other rivers and streams', and canals. A separate condition assessment is used for ditches. Further details are provided in Statutory biodiversity metric tools and guides - GOV.UK. In the consultation response, DEFRA committed to consideration of the following for all proposals:

• explore and test whether a simplified condition assessment could reduce costs, lessen burdens, and save time while retaining ecological integrity
• consider how the simplified condition assessment would work alongside the existing RCA
• explore whether adding a new distinctiveness category for heavily modified watercourses could help

ease BNG pressures for sites, particularly where achieving ecological improvements on heavily modified or constrained watercourses is challenging