6. Verification

Verification is complementary to operational monitoring of the individual control measures. In verification, actual cyanotoxin and/or cyanobacterial monitoring has its key role. Monitoring cyanotoxin concentrations in finished drinking-water or cyanobacterial biomass at recreational sites provides the overall reassurance that the whole system is working safely and people are not being exposed to cyanotoxins. Conceptually, verification is also complementary to validation. Validation may also analyse cyanotoxins or cyanobacteria, but for a different purpose and thus following completely different sampling schemes: For validation, cyanotoxin analyses are performed in the context of short-term and very specific research-type programmes e.g. under extreme bloom conditions in order to ascertain that a system challenged with a high load of cells or toxins can still cope effectively. Sampling schemes will target quantifying cyanotoxin removal rates. For verification, cyanotoxin analyses are performed at regular time intervals, primarily from the water to which people get exposed. Verification can be undertaken both by the operator of a facility (waterworks or recreational site) and by an independent surveillance agency. In practice, it is often done by both.

Developing a verification scheme for your setting requires consideration of adequacy of time intervals and sampling sites in relation to the heath risk from cyanotoxins that you assessed for your setting. It is important to understand that safety from exposure is not effectively generated by tight verification programmes, but rather by well designed and validated control measures together with their effective operational monitoring. This is particularly relevant to cyanotoxins, as their occurrence and concentrations may vary extremely rapidly when wind action shifts bloom locations in waterbodies. · For recreational sites, consider frequency, intensity and duration of blooms in relation to patterns of their use, both with respect to time (e.g. largely on week-ends or continuously as on camp sites) and number of users · For drinking-water supplies, consider time patterns of cyanobacterial occurrence in the source water and adapt sampling patterns accordingly. Triggers such as minimum turbidity levels in source water may be used for intensifying sampling and analyses for verification. · For both, consider whether analysing specific cyanotoxins or / and cyanobacterial biomass provides the more useful information about potential health risks. This will depend on dominant species and toxins expected from them. Your verification activities should also be documented in your Water Safety Plan, i.e. in the worksheet for your entries provided by this decision support tool. With such documentation, you can demonstrate having observed your duties of due diligence towards the surveillance authority responsible for your setting, and also towards journalists and the general public in case questions or incidents arise.

On to è Cyanotoxin building block for your Water Safety Plan