Under the Water Framework Directive, aquifers are classified according to their quality and quantity. The quality of groundwater is assessed by chemical tests, and the quantity of groundwater considers the impact that abstraction has on the amount of water left in the environment. Whichever is the poorest assessment (i.e. quality or quantity) dictates the overall groundwater body status, which can either be good or poor.

The Lower Greensand aquifer is currently at good status. However, monitoring data shows increasing trends in nitrate and pesticide concentrations in recent years, which means that a careful eye needs to be kept on nitrate and pesticide use in the catchment.

High concentrations of nitrate (an ingredient in artificial fertilisers) and pesticides in groundwater compromise its value as a source of drinking water supply, because these contaminants needs to be removed by artificial treatment before the water can be used for supply. These contaminants suggest a direct link between rural land management activities and groundwater quality.

The Brighton Chalk Block aquifer is at poor status, due to quantity issues. This is because a significant amount of groundwater is abstracted from the aquifer, principally for public water supply. It is therefore important to manage public demand for freshwater against a backdrop of a finite groundwater supply. The Brighton chalk is also vulnerable to diffuse rural and urban pollution. Consequently there is a risk, as there is to the Lower Greensand aquifer to the North, from rising trends in nitrate levels observed over the years.

Design by LTD Design Consultants and build by Garganey Consulting. From an original concept by the Herts and Middlesex Wildlife Trust.