River Delph Low DO Management
Since 2011 the River Delph has suffered with poor water quality following spring and summer flooding of the Ouse Washes. This complex issue, is a result of climatic change in rainfall events, but impeded by the siltation of the tidal river from Welches Dam through to King’s Lynn.
The Ouse Washes built in the 17th century by dutch engineers to drain and avoid the fens from flooding continues to work hard as designed as a flood defence asset. However since the washes became designated for its wildlife habitats, management pressure continues to avoid flooding in spring and summer and is actually subject to lawful controls on the drawmark water levels.
These constraints place significant challenges in the way water can be managed during the spring and summer months and have been subject to significant discussions at a number of forums attended by myself and members of LOFFCA. Indeed in 2016 this led to our creation and partnership with Cambridgeshire Acre and the formation of the OBML Catchment B Partnership.
In 2019 a break through was made by the EA by reaching agreement to enable a freshening flow through Earith Sluice, it took 6 years to achieve this. Pipes previously installed many years ago to enable a controlled flow were found blocked by concrete and a new set of pipes were installed in 2020. 3 years on, a licence to formally allow abstraction through these pipes is still awaiting approval. But sound progress has been made and no significant fish kills have been recorded since 2019.
In March 2023, the EA have instigated a review of the Ouse Washes Water Level Management Plan, something we have been seeking for the past decade.