there are a number of drains that connect to the river witham and that are protected by flood doors. these consist of a single pair of mitre gates that are designed to close if the level in the river rises above the level in the drain. several of these are navigable to the more adventurous boater. the river is also joined by the kyme eau, which connects to the sleaford navigation on which navigation will eventually be restored to sleaford. at antons gowt, a lock drops down into the witham navigable drains, a system of drainage ditches which are used to prevent flooding of the fens to the north of boston. since november 2008 there has been an active campaign by the billinghay skirth regeneration society to restore navigation on the river skirth, and the project has won the support of billinghay and other parish councils, the inland waterways association, the environment agency, lincolnshire county council and the lincolnshire waterways partnership.