Isambard Kingdom Brunel expressed fears that the Industrial Revolution was harming the environment, according to newly discovered letters.

The engineer worried about water supplies being polluted by waste, some of it created by his Great Western Railway.

Writing in 1842 about Bristol’s floating harbour, he said that “the abuses of using the Float as a common receptacle for rubbish have immensely increased”. He also cited waste from the local cotton mill, iron merchants, and ship, locomotive and bridge builders.

The pollution was “in some measure unavoidable”, he wrote, but too many were using the harbour as a dumping ground: “I fear still more from the apparent tendency of all persons to use the Float as a good receiver for that which cannot easily be got rid of elsewhere”.

His warning was among 15 documents unearthed by a retired engineer, Roger Henley, who was sifting through papers in the archive room at Bristol Port Company as part of his research for a new book about the port.