Thanks for your question. Have just asked the team and from their perspective both are of equal importance.
Know that makes it tricky to prioritise! However hopefully it provides some pointers on how teams can present different solutions, with an assessment of their efficacy in mitigating water quality degradation and/or flooding. Understanding the relative strengths of each solution for mitigating these different issues will ennable the team to understand how they might be deployed or combined to achieve both. Some solutions might naturally achieve both eg green infrastructure that is diversionary would mitigate contamination and excess water in the receiving bodies.
Thanks Chelsea, hope that helps a bit!