Abstract The Cam and Ely Ouse Chalk aquifer has been an important source of public water supply for over 100 years. In response to growing demand for water in the area in the 1970s and 1980 s, the National Rivers Authority developed the Lodes–Granta scheme to provide augmentation water to key rivers, subject to low flows. However, during the droughts in the late 1990s, the River Granta, which derives baseflow from the Chalk aquifer, was dry in some locations for several months. In response, the Environment Agency and Cambridge Water carried out investigations into the impacts of abstraction on the flow and ecology of the Granta and agreed to restrict abstraction from two operational groundwater sources during low flow periods. However, these abstraction restrictions could potentially result in a shortfall within the relevant public water supply zone under some climatic conditions and so Cambridge Water was considering increasing abstraction from an alternative source of groundwater within the catchment to retain the level of resilience of its supply. The Environment Agency was concerned that use of this abstraction could pose a risk of deterioration of the ecological status of the water body under the EU Water Framework Directive. This paper describes the investigations undertaken to assess the risk of deterioration and shows how these are being used to manage this risk going forward.

Abstract The UK, and England in particular, is the stronghold for chalk rivers, streams and wetlands in Europe. A number of sites are recognized as being important for nature conservation and have been designated as such under UK and European legislation. However, as the chalk is also an important aquifer for southern and eastern England, there have been significant impacts on these groundwater-dependent ecosystems from abstraction. Chalk rivers and streams have been used for centuries for mills and water meadows, so impacts have not just occurred in recent times. Intensification of agriculture in the twentieth century has added to the pressure by increasing levels of pollution, especially nitrates, with significant levels now being recorded. However, moves have been made to resolve some of these issues, with investigations into the effects of abstraction and options for reducing these impacts, research into the nature of the chalk aquifer so that it can be modelled more accurately, and assessment made of pollution pathways and their timescales. Associated projects have characterized the ecosystems associated with the chalk in more detail, enabling the mechanism for impacts to be better understood. While the extent of impacts is increasingly understood, action is also being taken to reduce their effects and restore chalk ecosystems.

Abstract The Crosby Warren Field is located onshore the UK, south of the Humber Estuary. It was discovered by RTZ Oil & Gas with the CW-1 (L46/12-3) well in 1986. The oil reservoir is Carboniferous, Namurian, Beacon Hill Flags sandstone, with gas found in Namurian sandstones of the Rough Rock, and the discovery well originally flowed waxy 40° API oil at rates of 45 bopd, which increased to nearly 700 bopd following fracture stimulation. The Beacon Hill Flags are a 10 m-thick group of laminated sandstones within a substantial gross thickness of sandstones, silts, muds and occasional thin claystones. The expected ultimate recovery for the field will be about 0.9 MMbbl of oil and 0.7 bcf of gas. Almost all of the oil and gas have already been recovered, and end of life for the field is expected to be in 2022.