1. Summing up and next steps

2. Metal bioavailability in regulatory context?
Bioavailability needs to be taken into account in the regulatory context – this reflects latest science!
The risk of not doing this is being over protective (taking measures where not needed) or under protective (not taking measures where needed)
It helps improving identification of real problems
We are dealing with complex models because they reflect complex realities – but keeping old approaches that are not backed by sound science is not an option
Simplified models and tiered approaches seem to be promising tools to implement bioavailability correction in practice
For classification and communication purposes a single EQS seems more practical: site specific EQS can have a role in vulnerability assessment

3. What to monitor where?
We need to extend widely the monitoring of dissolved concentrations of metals in the aquatic environment
Total concentrations may still be needed for other purposes (e.g. estimation of loads), but dissolved is needed for compliance checking of chemical status
Analytical issues may need careful attention (filtering, etc)
We need to monitor at least the most important parameters that influence bioavailability: Ca, DOC and pH
Additional costs seem to be in the range of € per sample
Recommendation to monitor together metal and supporting parameters
In some cases it might be possible to use of default values for Ca, DOC and pH – only if sufficiently develop datasets are available to ensure the variability in the water body is well known

4. Models? Very significant progress in past decade!
Simple models are needed to be implemented in tiered approaches
Simple models need to match the full models
Simplified tool is much appreciated, but important to document properly what is behind and how it relates with the full models
What if outside the boundaries of the model? Recommended a case by case approach – need clear documentation of possibilities
EU validation/endorsement of models and tools? How?

5. Tiered approach?
A main advantage of any tiered approach is that it is simple
Any tiered approach needs to be based on simplified models that are protective enough so that we have high confidence we do not overlook problems
The use of default values for Ca, DOC, pH in tiered approach is possible if they are protective enough to account for variability – needs to be base on a thorough knowledge of variability at water body level
Clear documentation on decision making is important
Flexibility in implementation steps of tiered approaches

6. Implementation?
Cu: quite substantial reduction in the number of EQS failures
Zn: some declines of EQS failures but less dramatic
Location of failures may change
Best practice needs to be promoted in sampling and analytical work
Basin wide interactions need to be carefully considered, e.g.
Insufficient waste water treatment may lead to higher DOC hence lower toxicity
A situation where high level of DOC results in compliance at local level may still create problems downstream (e.g. because of dilution with a tributary with low organic content or natural self-purification of DOC)

7. Permitting?
Bioavailability models are implemented to assess compliance with chemical standards in water bodies
Permits need to be based on BAT
Efficiency of waste water treatment usually involves measuring total concentrations, hence permits should keep total concentrations
However, it may be merit in including as well dissolved concentrations as it can be related to the compliance checking
Should permits be based on upstream DOC values in order to avoid allowing artificially high concentrations of metals in the effluents?

8. Next steps?
Pilot exercise to allow MS testing the user-friendly tool with their own data
Possibly a session prior to next WGE meeting in October to discuss findings
Document summarising the discussions will be produced and distributed
Presentation of the outcome of the discussions at the WGE tomorrow
Discussion on potential follow-up