The BBC reported that high levels of phosphates, nitrates and harmful bacteria were detected in the Thames, just upstream from Marlow, in Henley in June 2023, by environmental charity River Action. Phosphate and nitrate testing results indicate that the River Thames at Henley is excessively nutrient enriched and in a very poor ecological condition. The levels of E. coli recorded meant that the water in Henley would have posed a significant health risk to all water users, especially swimmers.
This was highlighted online by local naturalist Steve Backshall, when he accompanied River Action on the stretch of the river he uses regularly with his family.

If this is already the case in Henley today, what will the effect of 4,000 more people at the proposed Marlow film studio by for a local creaking Thames Water sewage treatment works and network?