Compliance Glossary

The annual average concentration of a substance in water that must not be exceeded to protect against chronic, long-term exposure.

How to calculate whether you comply with an annual average EQS — arithmetic mean of all readings over the calendar year.

Reference standards for industrial pollution control — companies must document BAT use to demonstrate compliance with the polluter-pays principle.

When a laboratory measurement is too low to be precisely quantified — regulatory guidance requires substituting half the limit of detection for compliance calculations.

An EQS expressed as a concentration in biological tissue (fish, crustaceans, molluscs) rather than in water — used for bioaccumulative substances.

A maximum permitted concentration of a pollutant in water, biota, or sediment, set to protect human health and the aquatic environment.

Mandatory monitoring method for estrogen-active substances (EE2, E2, E1) using biological effect tests rather than chemical analysis alone.

Substances under EU-wide monitoring for potential future listing as priority substances — typically monitored for 24 months before review.

The compliance goal for EU surface water — all priority substances and river basin specific pollutants must meet their EQS.

An EQS value that varies depending on the calcium hardness of the water body — used for certain metals including cadmium.

A single-reading concentration limit that must never be exceeded at any monitoring point — protects against acute pollution peaks.

Indicates that an AA-EQS alone provides sufficient protection for this substance — no separate maximum single-reading limit is required.

Indicates that no MAC-EQS value could be established — insufficient toxicological data for acute exposure. AA-EQS is the only applicable standard.

A class of systemic insecticides widely used in agriculture — several are listed as EU priority substances due to toxicity to aquatic invertebrates.

A grouped EQS of 0.2 μg/L inland that applies to the sum of all listed pesticides — individual substances must also meet their own EQS and contribute to this combined total.

A family of highly persistent synthetic chemicals used in industrial and consumer products — known as 'forever chemicals' due to their environmental persistence.

A priority substance classified as toxic, persistent and liable to bio-accumulate — subject to emissions cessation within 20 years.

A substance listed in Annex I of the EQSD that poses significant EU-wide risk to aquatic environments and requires harmonised EQS.

Synthetic insecticides derived from pyrethrin — highly toxic to aquatic insects and fish at very low concentrations (nanograms per litre).

A 6-year planning document covering all water management measures within a River Basin District — the primary EU water reporting vehicle.

A pollutant identified at national or river basin level as a significant local risk — not covered by the EU-wide priority substances list.

The main geographic unit for EU water management — typically one or more river catchments grouped together.

A weighting factor used to sum multiple PFAS compounds on a common PFOA-equivalent scale before comparing to the group EQS threshold.

A weighting system used for dioxin and dioxin-like compounds — each congener's toxicity is expressed relative to the most toxic form (TCDD = 1) and summed to give a single WHO-TEQ value for compliance.

A substance that is Ubiquitous, Persistent, Bioaccumulative and Toxic — found everywhere in the aquatic environment due to widespread historical use.