Short answers, pulled from the story.
The present day route of the river flowing generally southwestwards was created after about 10,000 years when the ice finally retreated and trapped water cut through the previous watershed. This event occurred following a glacial period that advanced into the Midlands from the north east and west about 50,000 years ago.
Charles I issued letters patent naming William Sandys as the grantee with powers to improve both this river and the River Teme. The navigation works were originally authorised by an Order in Council dated 1635.
The chemical status changed from good to fail in 2019 due to polybrominated diphenyl ethers and perfluorooctane sulphonate compounds. Reasons for less than good ratings include run off from agricultural land and discharge from sewage treatment plants.
Craig Openshaw completed the challenge in 29 hours and 18 minutes after starting at 01:18 on Sunday the 18th of July 2021. He swam 47.1 miles following a three month training programme.