Rivers: Vectors Of Pollution

Thirteen rivers, nine from the mainland and four from Ynys Môn (Anglesey), drain into the Menai Strait. While these rivers bring much-needed nutrients to the Strait, they can also act as vectors for toxic pollution Research indicates that a small percentage of global rivers, just 1%, are responsible for a staggering 80% of ocean pollution.

In 2021, the Menai Strait witnessed a concerning number of Combined Sewer Overflow (CSO) releases, with a total of 4,913 occurrences that lasted for a cumulative duration of 42,631 hours CSO refers to untreated raw sewage that is released into the environment during heavy rain events, and it can have detrimental impacts on marine and freshwater ecosystems This highlights the pressing need to address and mitigate the negative impacts of CSO releases on the Menai Strait and its delicate ecosystems.

The recent published data showed numerous CSO's in the South Menai mainland catchment with no CSO data. This is concerning as we can not ascertain the potential damage or level these CSO's are causing.

How does this impact the Menai Strait?

Water quality in the Menai Strait is generally good, with some sections achieving seasonal mussel classification ranging from B to A However, further improvement is needed to achieve higher levels of water quality It should be highlighted that the accuracy of water samples taken may be affected by the occurrence of Combined Sewer Overflow (CSO) releases, resulting in poorer water quality entering from the 13 rivers that flow in to the Strait.

This inconsistency may prevent a consistent A classification throughout the mussel zones, thus highlighting the need for measures to be taken to address this issue and improve water quality As a partnership forum, collaborative efforts are ongoing with stakeholders and relevant authorities to identify and address sources of pollution, including CSO releases By continuously monitoring and improving water quality, the ecological integrity of the Strait can be protected, safeguarding its sustainability as a crucial resource for wildlife, businesses, and recreational activities.