Nutrient Monitoring on the Test, Itchen and Meon

Nutrient Monitoring on the Rivers Test, Itchen and Meon 2024/25 (published 2026)

Working with the Test and Itchen Association, we have produced this report, which reviews all citizen science data from the Test, Itchen and Meon collected from water quality testing.

We conclude, from our analysis, that regulators should apply tighter standards for phosphate in particular, given the sensitive nature of our chalk streams.

We propose 'Upper Safe Limits' (USLs) for healthy chalk streams, based on Natural England targets for nutrients on designated sites.

Our data shows a pattern over the past 2 years :

• River Test and tributaries: 164 total USL breaches (7% of samples), with excessive phosphate in 36% of tests

• River Itchen and tributaries: 177 total USL breaches (9%), with excessive phosphate in 54% of tests

• River Meon: 93 total USL breaches (16%), with excessive phosphate in 88% of tests