the state of the witham had deteriorated by 1802, and the commissioners asked john rennie for advice. he stated that the kirkstead lock was badly placed, and the associated staunch was in danger of collapse. he recommended that it be demolished and rebuilt elsewhere, and also suggested that access to boston should be through the witham navigable drains, rather than the grand sluice, or that a new cut should be built to the south of the sluice, to rejoin the river at boston harbour. in 1803, he suggested that high bridge at lincoln should be demolished and rebuilt. four years later, he suggested that the locks at kirkstead and barlings should be removed, and replaced by one near washingborough church. the commissioners petitioned parliament in 1808, and a new act of parliament authorised the work, to be carried out by a company of proprietors. they could borrow £30,000 for the drainage element of the scheme and £70,000 for the navigation element. two new locks were built, one at stamp end and the other at bardney, which replaced the original locks. a new channel was cut near fiskerton, upstream of bardney, and the plan for a lock at washingborough was dropped. while stamp end lock was being rebuilt, an alternative route was provided, utilising the sincil dyke and the south delph. rennie recorded that branston delph, carlton dike, nocton delph and timberland dike were navigable at the time. the proprietors obtained three more acts of parliament, in 1812, 1826 and 1829, all with the main aim of allowing more capital to be raised.