Hydrogeological studies of the Lincolnshire Limestone aquifer in south Lincolnshire combined with the development of mathematical models were reported in the 1970s. However, these studies concentrated on the aquifer and did not consider the total catchment conditions of both the groundwater and surface water systems. Greater importance is now placed on understanding total stream and river flows and preparing models which can predict the change in flows due to different abstraction scenarios; this has required a complete review of ‘the catchment’ of the Lincolnshire Limestone and the associated models. This review has led to the development of improved methods of estimating the recharge due to runoff, identifying locations such as inliers of the Lincolnshire Limestone in the river valleys where runoff can enter the aquifer system, improving the representation of wild bores (uncapped overflowing artesian boreholes) and representing leakage through the overlying strata in the east of the study area. These developments now allow the simulation of total river flows, especially low flows. A novel type of diagram has been devised for representing inflows, outflows and changing flow conditions along the streams and rivers.