 the river ancholme is a river in lincolnshire, england, and a tributary of the humber estuary. it rises south of bishopbridge (west of market rasen) and flows north through the market town of brigg before flowing into the humber at south ferriby. north of bishopbridge, where the river rase joins the ancholme, the river is substantially canalized and runs in two intertwining channels. the main straight channel carries most of the water and is known as the new river ancholme, whereas the old river ancholme maintains its natural course but is mostly reduced to a drain, except around the town of brigg where the two rivers create an island in the centre of brigg known as 'island carr'. the ancholme drains a significant part of northern lincolnshire between the trent and the north sea, but is no longer economically important for tranport.  ==history== in its natural post-glacial state, the river's valley was flat-bottomed, for it had formed the bed of the glacial lake ancholme, on an outwash delta as the ice retreated,c. r. twidale, "glacial overflow channels in north lincolnshire", transactions and papers (institute of british geographers), no. 22 (1956:47-54). and consequently fenny. as early as the 13th century local landowners paid subscriptions for work to be undertaken with the aim of facilitating navigation and land drainage. in 1635, owersby-based local landowner, sir john monson drained the ancholme valley by cutting a straight new channel making two rivers at brigg, which made the town less vulnerable to flooding. the draining of the ancholme level was a lesser project among the fenland "improvements" undertaken under contracts to patentees by the government of charles i in the 1630s; "with the possible exception of the ancholme level the draining of the fens was executed and defended by a continuous and unscrupulous use of the power and authority of the royal government to manipulate local institutions and to overawe the local populace."mark e. kennedy, "charles i and local government: the draining of the east and west fens" albion: a quarterly journal concerned with british studies 15.1 (spring 1983):19-31) in 1766, landowners in the ancholme floodplain contracted thomas yeoman to survey the river. he pointed to the decay of ferriby sluice and an act for navigation was passed in 1767, leading to a new sluice and lock at ferriby in 1769. {{citation|first=edward|last=paget-tomlinson|title=the illustrated history of can
Rivers_of_Lincolnshire Tributaries_of_the_Humber