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Operator Monitoring

Some of our authorisations require that environmental monitoring is carried out and the results reported back to SEPA. We call this operator monitoring.

Why use operator monitoring?

We expect all regulated operators to comply with their environmental obligations. This is a key element of Our Approach to Regulation. We also expect those operators to be responsible for managing and understanding their own impact on the environment. Operators that want to do the right thing will be supported, whilst those seeking to benefit from non-compliance will be targeted.

In certain sectors, permit reforms mean that operators performing authorised activities are now obliged to monitor and report back to us in support of our regulation of those activities. The data they submit becomes part of the range of evidence we use in our compliance verification work.

By requiring that an increased proportion of environmental evidence is collected by operators at their own sites under operator monitoring arrangements, we will be able to better allocate our own monitoring resource to focus on those activities that are causing or are likely to cause the most environmental harm.

Getting our evidence right

We’re clear that the evidence we use to make regulatory decisions must be fit for purpose. This principle applies not only to the data we generate internally, but also to data that is provided to us by (or on behalf of) operators. In order to maintain confidence in our regulatory decision making, operator monitoring data must meet our minimum standards for data integrity.

Measurement Assurance and Certification Scotland (MACS)

To help operators achieve those standards, we have established Measurement Assurance and Certification Scotland (MACS) - our quality assurance certification scheme. MACS comprises a range of performance standards designed to ensure that operator monitoring data is fit for regulatory assessment. Its remit extends across the entire monitoring process; from planning and scheduling of monitoring activity to sampling, analysis and data reporting.

Where an organisation conforms with the requirements of MACS, we can be confident that the operator monitoring data they produce will be of a standard that meets our minimum quality requirements. To ensure that this remains the case, those organisations will be routinely audited.

Scheme documentation

There are five types of document currently associated with our MACS scheme:

  • Performance Standard - a document that sets out the requirements which MACS participants must abide by when producing data under operator monitoring arrangements.
  • Addendum - a temporary document detailing an amendment to an existing MACS document.
  • Technical Guide - a document intended to support MACS participants; either by providing assistance on how best to meet a specific requirement of MACS or by explaining how SEPA will manage a particular MACS governance process.
  • Form - a document for completion by a MACS participant, which is submitted to SEPA to support a process detailed in a Performance Standard or Technical Guide.
  • Operator Specific Criteria - a document for use in conjunction with MACS Performance Standards, containing specific requirements which are relevant only to an individual operator.

At present, our MACS approach has been formally adopted in two sectors - Water Supply & Waste Water and Finfish Aquaculture. Details of the current MACS requirements applicable in each sector can be found below:

Water Supply & Waste Water

In this sector, our MACS approach is founded on ISO/IEC 17025, the most widely recognised and commonly adopted international quality standard for laboratories performing environmental analysis. As a prerequisite for acceptance onto the MACS scheme in this sector, we require that organisations are accredited by the United Kingdom Accreditation Service (UKAS) to ISO/IEC 17025.

Upon an organisation’s application to the scheme, UKAS will perform an initial assessment audit. Subsequent MACS surveillance audits will be incorporated alongside that organisation’s annual ISO 17025 audit. An agreement is in place with UKAS to allow for all audit outcomes to be shared with us.

Performance standards Technical guides Forms Operator Specific Criteria
Sampling and chemical testing of water Updating MACS documentation Operator document change request form Scottish Water
Sample and data management Guidance on sub-contracting analysis Operator sub-contracting request form Ayr Environmental Services Operations
Sample and data management – addendum A Dealing with non-conformance Operator concession request form Caledonian Environmental Levenmouth Treatment Services
      Kelda Water Services Ltd
      Saur Glasgow
      Veolia Water Operational Services
      Veolia Water Outsourcing Limited

Finfish Aquaculture

The introduction of a MACS scheme is a key component of the revised regulatory framework for the Finfish Aquaculture sector. In consultation and collaboration with operators, their service providers and other interested parties, we are continuing to implement this new MACS approach in a phased manner. Our current requirements may be found below.

Auditing arrangements for the Finfish Aquaculture sector are presently in development.

Update: July 2023

In line with the phased implementation of our MACS approach, an updated version of performance standard MACS-FFA-PS-01 "Sampling of soft-substrate" has been published. Where multiple versions of the same MACS document are available, operators must ensure that they use the version referenced in their authorisation.

Performance Standards

Technical Guides


Sampling of soft-substrate (Version 1 - March 2022)

Dealing with non-conformance

Operator concession request form

Sampling of soft-substrate (Version 2 - July 2023)



Physical and chemical testing



Biological testing



Contact us

If you have any questions, or require any further information or advice on any aspect of operator monitoring or MACS, please contact us.