Editing River Little Ouse (section)

==Water quality==
The Environment Agency measure the water quality of the river systems in England. Each is given an overall ecological status, which may be one of five levels: high, good, moderate, poor and bad. There are several components that are used to determine this, including biological status, which looks at the quantity and varieties of [[invertebrate]]s, [[angiosperm]]s and fish. Chemical status, which compares the concentrations of various chemicals against known safe concentrations, is rated good or fail.<ref>{{cite web |url=http://environment.data.gov.uk/catchment-planning/help/glossary |website=Catchment Data Explorer |title=Glossary (see Biological quality element; Chemical status; and Ecological status) |publisher=Environment Agency |access-date=15 May 2017}}</ref>

The water quality of the River Little Ouse system was as follows in 2019.
{| class="wikitable"
|-
! Section !! Ecological Status !! Chemical Status !!Length !! Catchment !! Channel
|-
| {{waterqual_title |desc=Little Ouse (US Thelnetham) |asset=GB105033043060 |accessdate=9 October 2017}} 
| {{waterqual_bad}} 
| {{waterqual_fail}} 
| {{convert|5.4|mi}}
| {{convert|15.27|sqmi}}
| heavily modified
|-
| {{waterqual_title |desc=Little Ouse (Thelnetham to Hopton Common) |asset=GB105033043110 |accessdate=9 October 2017}} 
| {{waterqual_poor}} 
| {{waterqual_fail}} 
| {{convert|3.0|mi}}
| {{convert|2.46|sqmi}}
| heavily modified
|-
| {{waterqual_title |desc=Little Ouse (Hopton Common to Sapiston Confl) |asset=GB105033043100 |accessdate=9 October 2017}} 
| {{waterqual_mod}} 
| {{waterqual_fail}} 
| {{convert|7.8|mi}}
| {{convert|20.70|sqmi}}
| heavily modified
|-
| {{waterqual_title |desc=Little Ouse (Sapiston Confluence to Nuns Br) |asset=GB105033043090 |accessdate=9 October 2017}} 
| {{waterqual_mod}} 
| {{waterqual_fail}} 
| {{convert|4.3|mi}}
| {{convert|19.00|sqmi}}
| heavily modified
|-
| {{waterqual_title |desc=Little Ouse River |asset=GB105033043400 |accessdate=9 October 2017}} 
| {{waterqual_mod}} 
| {{waterqual_fail}} 
| {{convert|12.2|mi}}
| {{convert|43.53|sqmi}}
| heavily modified
|}

The Environment Agency data for the upper river covers a short section of the Little Ouse, and a long section of the stream that flows northwards from Rickinghall and Botesdale. They have set a target for improving the water quality on this section from bad to poor by 2021. Like most rivers in the UK, the chemical status changed from good to fail in 2019, due to the presence of polybrominated diphenyl ethers (PBDE) and perfluorooctane sulphonate (PFOS), neither of which had previously been included in the assessment.<ref>{{cite web |url=https://environment.data.gov.uk/catchment-planning/help/usage#chemical-status |archive-url=https://web.archive.org/web/20240314040920/https://environment.data.gov.uk/catchment-planning/help/usage#chemical-status |archive-date=14 March 2024 |url-status=live |title=Chemical Status |publisher=Environment Agency |year=2023}}</ref>