Chemical Quality Standards and Assessment | Umweltbundesamt

Chemical assessment methods

A wide range of substances from households, industry, trade, transport and agriculture are discharged into waters. As analytical techniques become ever more advanced, an increasing number of substances is found in even smaller concentrations in water bodies. For such substances, the EC Water Framework Directive requires assessment of their relevance and groups substances into those with EU-wide importance and those with local importance for surface waters. A substance is relevant, when it exceeds its environmental quality standard. Then this standard is set legally and measures against this pollution have to be taken.

Additionally a 7-point chemical water quality classification provides an important basis for assessing the pollution of inland surface waters in Germany.

EU-wide environmental quality standards – chemical status

Chemical status is determined from the defined EU-wide environmental quality standards for the 33 priority substances currently listed in the EC Water Framework Directive and 8 other substances regulated on a European-wide basis under the older Directive on pollution caused by certain dangerous substances discharged into the aquatic environment (Directive 2006/11/EC, formerly: 76/464) and the action value for nitrate 50 mg/l nitrate under the EU Nitrates Directive. The provisions of the Environmental Quality Standard (EQS) Directive 2008/105/EC and the Nitrates Directive were adopted into Annex 7 of the Surface Waters Ordinance in 2011. The environmental quality standards Directive 2008/105/EG was updated in 2013 (2013/39/EU), and now regulates a total of 45 priority substances, which shall be included into the Surface Waters Ordinance by 2015. The standards for the 12 new priority substances will come into force in 2018. Additionally standards for eleven "old" substances have been amended.

The chemical status is assessed in two classes: If the environmental quality standards is complied with, the status is "good", otherwise it is "not good". "Good chemical status" is an environmental for all waterbodies - "natural", "artificial" and "heavily modified" ones. These are labeled blue for “good” and red for “not good chemical status”. Priority substances must be measured if there are any emissions.
There are two kinds of environmental quality standards: An annual average standard (AA-EQS) is set for all priority substances. For selected ones with high acute toxicity, a maximum allowable concentration (MAC-EQS) is additionally specified, which must not be exceeded in all samples. A MAC-EQS is considered necessary where the ratio of acute to chronic toxicity is less than 12. For hexachlorobenzene, hexachlorobutadiene and mercury, which highly accumulate within the food chain, an environmental quality standard for biota was additionally defined. The Member States are at liberty to specify an environmental quality standard for water corresponding to this biota figure for analytical monitoring. Germany has choosen this for HCB and hexchlorobutadiene, but not for mercury due to methodological problems.

The environmental quality standard for coastal waters and seas were set using test results for marine organisms as well. If such tests are not available the inland surface water standard is just devided by 10 to derive a coastal and sea standard. The marine protection conventions prompted the objective of phasing out emissions of priority hazardous substances within one generation. 21 of the 45 priority substances are prioritized as hazardous.

The EC Water Framework Directive stipulated that the priority substances listed in Annex X should be revised every four years. This was extended to 6 years in accordance with the management plans by Directive 2013/39/EU. The new Directive has reduced the level of monitoring required for the so-called ubiquitous, non degradable and widespread dispersed substances, including mercury and dioxins. Also new is the mandatory watch list with a maximum of 14 substances. For the first upcoming list diclofenac and the two hormones E2 and EE2 are already nominated by the directive. The watch list must be updated every 2 years, and a substance must not remain on the list for more than 4 years.

National environmental quality standards – ecological status

Specific pollutants are assessed within the classification of ecological status. For specific pollutants that are discharged in significant quantities, the Member States must derive environmental quality standards to protect the aquatic community. In Germany substance volumes leading to concentrations of more than half the environmental quality standard at representative monitoring sites are defined as significant. Environmental quality standards with legally binding validity have been specified for a total of 162 pollutants in the German Surface Waters Ordinance. Compliance with environmental quality standard is verified using annual averages as prescribed by the EC Water Framework Directive.

Environmental quality standard for the ecological status of surface waters are defined on the basis of an EU chemical assessment as prescribed in Annex V, 1.2.6 of the EC Water Framework Directive. Valid long-term tests regarding the substance’s effects on the trophic levels algae, amphipods and fish are compiled, and the most sensitive of these values is selected. However, as organisms in nature may be more sensitive than those used in laboratory tests, this smallest figure is divided by an assessment factor in order to calculate the environmental quality standard. If valid long-term toxicity tests are available for all levels, this factor is generally 10. If data is missing, it will be 100 or more.

Some environmental quality standards have very low values and the Commission Directive 2009/90/EC on technical specifications for chemical analysis and monitoring of water status demands to use analytical methods with limits of quantification lower than one third of the standard. Where no analytical method satisfying this requirement exists, monitoring is to be based on the best available techniques not entailing excessive costs. Since accumulable substances are primarily adsorbed to “suspended solids” and limits of quantification in this matrix better fit to this requirement Germany has set environmental quality standards for some accumulable substances for the matrix supended solid.

Chemical water quality classification

The water quality classification was developed by the Federal Government and Länder in Germany prior to the Water Framework Directive's entry into force. As long as there are no binding values for classification of a good ecological status (e.g. for nutrients), Germany will continue to use the holistic chemical water quality classification, which also takes into account remote effects in the oceans (this extends to reporting under the EU Nitrates Directive).

The substance concentrations corresponding to quality class I characterizes a status that is free from anthropogenic impairments. For nutrients, quality class II contains values derived from previous assessment procedures. The subsequent classes result from multiplying the value of quality class II by a factor 2.

Chemical water quality classification has the following classes:

Quality class I (dark blue): no anthropogenic pollution: geogenic background value (for natural substances)

Quality class I-II (light blue): lightly polluted up to half value of class II

Quality class II (dark green): moderately polluted target value complied with

Quality class II-III (yellow-green): critically polluted up to twice value of class II

Quality class III (yellow): heavily polluted up to four times value of class II

Quality class III-IV (orange): very heavily polluted up to eight times value of class II

Quality class IV (red): excessively polluted more than eight times value of class II