Bourne Eau is a short river which rises from an artesian spring in the town of Bourne in Lincolnshire, England, and flows in an easterly direction to join the River Glen at Tongue End. Within the town, it once powered three water mills, one of which is now a heritage centre. At Eastgate, it becomes much wider as it was navigable in the 18th and 19th centuries, and this was the location of the terminal basin. Below the town it is an embanked river, as its normal level is higher than that of the surrounding Fens. Navigation ceased in the 1860s and the river now forms an important part of the drainage system that enables the surrounding fen land to be used for agriculture.