Nitrates monitoring

Our groundwater monitoring networks ensure that Scotland’s groundwater supplies are adequately protected.

SEPA’s nitrate monitoring network aims to identify areas affected by nitrate pollution, or at risk of being affected, and to find out if any improvement actions taken to address nitrate problems are effective.

To achieve these aims, SEPA currently monitors 270 groundwater sites across Scotland at annual, quarterly or monthly frequencies.

Data from the nitrate monitoring network is used to help the Scottish Government define nitrate vulnerable zones (NVZs). The primary source of nitrate in Scotland is agricultural diffuse pollution . Action programmes are introduced within NVZs that aim to reduce inputs of nitrate to the water environment, and so address diffuse pollution problems. NVZ action programmes require land managers to follow a range of measures such as controlling the timing and quantities of fertiliser applied to land.

The introduction of NVZs and action programmes is driven by the EU Nitrates Directive (91/676/EEC)that aims to reduce or prevent the pollution of water caused by the application and storage of organic and inorganic fertiliser on agricultural land. By controlling land use management, the legislation aims to protect drinking water supplies, aquatic ecosystems and other legitimate uses of water. Nitrate problems usually occur in groundwater, where concentrations can approach or exceed standards for drinking water, and in estuaries and transitional waters, where excess nutrients can result in algal blooms and eutrophication.

Nitrate concentrations in groundwater are monitored at regular intervals to ensure that they remain below the standard of 50mg/l. Where concentrations exceed this level, or there is a risk they will do so, the areas of land which drain into these waters are designated as NVZs.

The designation of NVZs needs to be reviewed at least every four years. In 2013, a new NVZ review methodologywas developed by SEPA, in consultation with the Scottish Government, the National Farmers Union Scotland (NFUS)and other stakeholders.

The new methodologyutilises data from SEPA’s nitrate monitoring network together with a number of additional lines of evidence to assess confidence in the outcome. This new methodology provides greater reliability and transparency than previous methods, and is integrated with assessment requirements of the Water Framework Directive (2000/60/EC).

Groundwater bodies are specific units defined under the Water Framework Directive (WFD) to enable the management of groundwater resources. Groundwater bodies may be grouped to aid assessment. The new methodology is based on groundwater bodies and groups, and incorporates WFD parameters of status and risk. Consultation on NVZ review proposals based on the new methodology was undertaken in 2014.

SEPA’s groundwater monitoring network for the Nitrates Directive and WFD is regularly reviewed to make sure that it remains aligned with identified and emerging risks to the water environment, and that water supplies and aquatic ecosystems are protected going forward.